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Pure ZnO and ZnO–Bi2O3 nanocomposites with 5 wt% and 10 wt% of Bi2O3 content were synthesized using the co-precipitation method. Optical properties such as refractive index (n), extinction coefficient (k), bandgap (Eg), and Urbach energies, as well as the band structure, were determined by modeling the experimental transmittance and reflectance UV–Vis spectra. The deduced bandgap and Urbach energies for pure ZnO (3.758 eV) increase with the increase of the doping degree of Bi2O3 in ZnO–Bi2O3 nanocomposite films. X-ray diffraction and scanning electron microscopy (SEM) was used to study the structural and morphological properties of these nanocomposite films. Pure ZnO and nanocomposites with Bi2O3 exhibit crystalline domains with wurtzite hexagonal structures, and as the doping degree of Bi2O3 increases, the crystallite size decreases. Based on SEM micrographs, the ZnO nanoparticles (NPs) structure shows the presence of aggregation. Moreover, Bi2O3 NPs in the nanocomposite film led to the further aggregation in the form of large rods. The elemental and chemical properties of the nanocomposites were investigated using infrared and energy-dispersive X-ray spectroscopy. The charge transfer process in the studied system is between ZnO and Bi2O3 conduction bands. Density-functional theory (DFT) calculations were performed for ZnO, Bi2O3, and ZnO-Bi2O3 compounds to investigate structural, optical, and electronic properties, being in agreement with the experimental results.

Polyethylene oxide (PEO) complexed with molecular iodine (I2) forming PEO/I2 complex composites stand‐free films were investigated using dielectric relaxation, X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometry, structural and morphological techniques. Scanning electron microscopy was used to monitor the variation in the surface morphology and the related roughness. 2D Energy-dispersive X-ray spectroscopy (EDX) measurements enabled to observe the distribution of iodine on the film surface. High resolution XPS measurements were used to define the iodine anion types and the metallic iodine existence, as well as the relevant concentrations based on the binding energies. The dielectric relaxation measurements were carried out over the frequency range from 0.1 to 107 Hz and temperature range from 155 to 330 K. Dielectric loss (ε′′) curves were fitted to the Havriliak–Negami (HN) model for one and/or two relaxation peaks (α and β), with and without the electrical conductivity contribution term, in order to deduce the relaxation time (τ) and the dielectric strengths (Δε), in addition to the electrical conductivities (σ). The temperature-dependent data of β- and σ- relaxations follow the law of Arrhenius thermal activation indicating the presence of typical glass-forming polymers. Δε of α-relaxation obeys the curvature pattern of Vogel-Tammann-Fulcher (VTF) thermal activation law. The electrical conductivity of the system increases 6000 folds by doping PEO with 5 wt% of iodine at the same temperature (293 K)., The authors would like to thank Jordan University of Science and Technology; this research was supported by the Deanship of Scientific Research under Grant Number: 420/2019. The authors extend thanks to the Lehrstuhl Experimentelle Physik III, Technische Universitat Dortmund, Germany for offering the measurements via the broadband impedance spectroscopy and the full technical and experimental support.

The determination of the optical band gap energy ( E g ) is important for optimization of the generation of electron/hole pairs in semiconductor materials under illumination. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) has been largely employed for the study of amorphous and polycrystalline materials. In this paper, the authors demonstrate, step by step, how to use the K-M function and apply it thoroughly to the determination of the E g of TiO2 semiconductor powder (pressed at different thicknesses) from diffuse reflectance spectroscopy (DRS) measurements. For the sample thicknesses 1–4 mm, E g values of 3.12–3.14 eV were obtained. With this work it is envisaged a clarification to the procedure of determination of the E g from the K-M theory and DRS data, since some drawbacks, and misconceptions have been identified in the recent literature. In particular, the widely used practice of determining the E g of a material directly from the K-M function is found to be inadequate.

This work evaluated the photocatalytic activity of 3D-printed cementitious mortar specimens functionalized with TiO2 nanoparticles to obtain a multifunctional and smart concrete. This research aims to assess the influence of different parameters related to the functionalization process such as adsorption, coating time gaps, and coating rates on the degradation efficiency of the functionalized cementitious specimens. Each specimen was evaluated under the degradation of Rhodamine B (RhB) in an aqueous solution using a sun-light simulation. The obtained results showed a decrease in adsorption (under dark condition) with increasing the sample curing age. The highest photocatalytic efficiency was observed for coated samples aged 7 days. By increasing the coating rates, the photocatalytic efficiency is enhanced. Nonetheless, regardless of the coating rates, all the specimens showed an increase in photocatalytic efficiency for longer time periods of light exposition, i.e., after 8 h of irradiation, This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. The authors acknowledge the support of the DST group construction company for funding the project Chair dst/IB-S: Smart Systems for Construction. The first two authors would like to acknowledge the PhD grants SFRH/BD/143636/2019 and SFRH/BD/137421/2018 provided by the Portuguese Foundation for Science and Technology (FCT). Additionally, the authors would like to acknowledge FCT for the financing this research work by the project NanoAir PTDC/FIS-MAC/6606/2020 and the Strategic Fundings UIDB/04650/2020-2023 and UIDB/04029/2020

Rutherford backscattering spectrometry, X-ray photoelectron and X-ray energy dispersive spectroscopies were employed to analyse Bi incorporation into ZnO:Al and ZnO:Ga transparent and electrically conductive thin films deposited by d.c. magnetron sputtering, with thickness in the range of 300–400 nm. Sputtering was performed in an argon atmosphere from two targets in confocal geometry being one composed of either ZnO:Al2O3 or ZnO:Ga2O3 composites and the other a Bi metal target. The content of bismuth dopant in the ZnO matrix was controlled by the respective target current density (JBi) in order to attain a high optical transparency (>80%) in the visible region. For ZnO:Al,Bi films Bi content varied from 0.1 to a maximum of 1.5 at.% when varying JBi from 0.06 to 0.26 mA cm−2. However, for ZnO:Ga,Bi films, deposited in similar conditions, Bi reached a maximum overall layer content of 2.4 at.%, with a surface enrichment content that varied from 1.3 to 8.8 at.%. It was also observed that the Bi content in the topmost layers of the films is slightly depleted due to thermal evaporation upon thermal annealing in vacuum at 350 °C. It is envisaged applications for these films as transparent photoelectrodes and thermoelectric materials., Fundação para a Ciência e a Tecnologia (FCT, Portugal)/PIDDAC through the Strategic Funds project reference UID/FIS/04650/2013. Filipe Correia is grateful to the Fundação para a Ciência e a Tecnologia for the Ph.D. Grant SFRH/BD/111720/2015. Paulo Salvador is grateful to the Project WinPSC - POCI-01-0247-FEDER-017796, for the research grant, co-funded by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. Joana Ribeiro is grateful to University of Minho for the Grant UMINHO/BI/66/2017

Poly (methyl methacrylate) (PMMA) is a thermoplastic synthetic polymer, which displays superior characteristics such as transparency, good tensile strength, and processability. Its performance can be improved by surface engineering via the use of functionalized thin film coatings, resulting in its versatility across a host of applications including, energy harvesting, dielectric layers and water purification. Modification of the PMMA surface can be achieved by atomic layer deposition (ALD), a vapor-phase, chemical deposition technique, which permits atomic-level control. However, PMMA presents a challenge for ALD due to its lack of active surface sites, necessary for gas precursor reaction, nucleation, and subsequent growth. The purpose of this review is to discuss the research related to the employment of PMMA as either a substrate, support, or masking layer over a range of ALD thin film growth techniques, namely, thermal, plasma-enhanced, and area-selective atomic layer deposition. It also highlights applications in the selected fields of flexible electronics, biomaterials, sensing, and photocatalysis, and underscores relevant characterization techniques. Further, it concludes with a prospective view of the role of ALD in PMMA processing., e Fundação para a Ciência e Tecnologia (FCT, Portugal)/PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES

This work reports the production and characterization of optically transparent Nb-doped TiO2 thin films with enhanced thermoelectric properties deposited on glass and Si by reactive d.c. magnetron sputtering in high vacuum. The purpose of these films is to harvest thermal energy from the environment and convert it to electrical energy. Several process parameters, such as reactive and working gas flow rate, deposition temperature, target current density and post-annealing conditions, directly affect the morphology and crystalline structure of the thin films. The optimization of these parameters results in thin films with thickness of 120–300 nm, maximum average optical transmittance in the visible range of 73%, n-type electrical resistivity of 0.05 Ω·cm, thermal conductivity around 1.5 W·m−1·K−1 and a maximum absolute Seebeck coefficient of 223 μV·K−1. The resulting maximum thermoelectric power factor is 60 μW·K−2·m−1 and the maximum thermoelectric figure of merit is 0.014. Hence, modifying the optical, electric, thermal and thermoelectric properties of the thin films enables their suitability for applications as transparent electrodes in photovoltaic systems and touch displays, amongst other devices., Joana Ribeiro is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. grant SFRH/BD/147221/2019. Filipe Correia is grateful to the FCT, Portugal, for the Ph.D. grant SFRH/BD/111720/2015. Funding is also gratefully acknowledged from FCT/PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023 and from the Spanish Ministerio de Ciencia e Innovación (MICINN) through grants SEV-2015-0496 (FUNMAT) and CEX2019-000917-S (FUNFUTURE) in the framework of the Spanish Severo Ochoa Centre of Excellence program, and grant PID2020-119777GB-I00 (THERM2MAIN).

The experiment at HASYLAB/DESY was performed within the project I-20180036 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Filipe Correia is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. Grant SFRH/BD/111720/2015. Joana Ribeiro is grateful to the Project WinPSC - POCI-01-0247-FEDER-017796, for the research grant from the Agência Nacional de Inovação, co-funded by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. The authors acknowledge the funding from the Fundação para a Ciência e Tecnologia (FCT, Portugal) / PIDDAC through the Strategic Funds project reference UIDB/04650/2020-2023. Part of this work was developed within the scope of the project i3N, UIDB/50025/2020, financed by national funds through the FCT/MEC. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020- WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2. The authors would like to thank the valuable help from Dr. Alec LaGrow and Dr. Dr. Alex Bondarchukat the International Iberian Nanotechnology Laboratory (INL), in Braga, Portugal, for the STEM/HRTEM experiments, Transparent undoped ZnO and additionally doped with Ga and Bi thin films were produced by magnetron sputtering. The thin films were comprehensively characterized by X-ray absorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission and scanning transmission electron (TEM, STEM) microscopy and Raman spectroscopy. All undoped and doped films crystallise in a ZnO phase with the hexagonal wurtzite crystal structure. The local structure of the thin films was investigated by temperature-dependent X-ray absorption spectroscopy at the Zn and Ga K-edges, as well as at the Bi L3-edge. It was found that the doping of Ga3+ and Bi3+ ions in the ZnO wurtzite structure produces distinct effects on the thin film microstructure. The substitution of Zn2+ ions by smaller Ga3+ ions introduces a static disorder to the thin film structure, which is evidenced by an increase in the mean-square relative displacements σ2(Zn‒O) and σ2(Zn‒Zn). At the same time, large Bi3+ ions do not substitute zinc ions, but are likely located in the disordered environment at the ZnO grain boundaries. This conclusion was directly supported by energy-dispersive X-ray spectroscopy combined with TEM and STEM observations as well as by resonant and non-resonant μ-Raman experiments at room temperature, where the ZnO and ZnO:Bi spectra are similar, suggesting a lack of structural disorder in the wurtzite cell. On the other hand, the Raman disorder-activated phonon is pronounced for Ga-doping of the ZnO lattice, confirming the compositional disorder. Both XRD and XPS ruled out Ga2O3 phase in Ga-doped ZnO; conversely, Bi2O3 and a small amount of Bi‒metal phases are clearly discerned by XPS experiments, further suggesting that Bi is not incorporated in the ZnO wurtzite cell, but segregated to grain boundaries.--//--This is the preprint version of the following article: Filipe C. Correia, Joana M. Ribeiro, Alexei Kuzmin, Inga Pudza, Aleksandr Kalinko, Edmund Welter, Adelio Mendes, Joana Rodrigues, Nabiha Ben Sedrine, Teresa Monteiro, Maria Rosário Correia, Carlos J. Tavares; The role of Ga and Bi doping on the local structure of transparent zinc oxide thin films, Journal of Alloys and Compounds: Volume 870, 25 July 2021, 159489, which has been published in final form at https://www.sciencedirect.com/science/article/abs/pii/S0925838821008987?via%3Dihub#! This article may be used for non-commercial purposes in accordance with Elsevier Terms and Conditions for Sharing and Self-Archiving. This work is licensed under a CC BY-NC-ND license., Project I-20180036 EC; CALIPSOplus under the Grant Agreement 730872; Ph.D. Grant SFRH/BD/111720/2015; Project WinPSC - POCI-01-0247-FEDER-017796 from the Agência Nacional de Inovação, co-funded by the European Regional Development Fund (ERDF); Fundação para a Ciência e Tecnologia (FCT, Portugal) / PIDDAC; i3N, UIDB/50025/2020, financed by national funds through the FCT/MEC; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.

Bi2O3 nanocone films functionalized with an overlayer of TiO2 were deposited by d.c. reactive magnetron sputtering. The aforementioned nanocone structures were formed via a vapour-liquid-solid (VLS) growth, starting from a catalytic bismuth seed layer. The resultant nanocones exhibit an improved surface area, measured by atomic force microscopy, when compared to non-VLS deposition of the same metal oxide. X-ray diffraction texture analysis enabled the determination of the crystallographic β-phase of Bi2O3. A very thin TiO2 overlayer (6 nm thick), undoped and doped with nitrogen, was deposited onto the nanocones template, in order to functionalize these structures with a photocatalytic, self-cleaning, cap material. N-doped TiO2 overlayers increased the selective absorption of visible light due to nitrogen doping in the anatase cell, thus, resulting in a concomitant increase in the overall photocatalytic efficiency., The authors acknowledge the financial support of the project “NANOPURIFY—Development of photocatalytic panels for air treatment units, Vieira & Lopes Lda.”, with the reference 024121, co-funded by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. Filipe C. Correia acknowledges the financial support from the Fundação para a Ciência e Tecnologia (FCT) for the Ph.D grant SFRH/BD/111720/2015.

Dendritic growth of bismuth oxide nanostructured films was accomplished by reactive magnetron sputtering. The deposition of the Bi2O3 template layers was adapted to abide a vapour-liquid-solid mechanism in order to develop a 3D growth morphology with high surface area templates for photocatalytic applications. TiO2 photocatalytic thin films were deposited at a later stage onto Bi2O3 layers. The obtained heterostructured films were characterized by scanning electron microscopy, X-ray diffraction and atomic force microscopy. Additionally, the photocatalytic efficiency was assessed by conducting an assay using methylene blue dye as testing pollutant under a UV-A illumination. The photocatalytic tests revealed that the Bi2O3 layers functionalized with TiO2 thin films are more efficient at degrading the pollutant, by a factor of 6, when compared with the individual layered films., The authors acknowledge the funding from the Portuguese institution Fundacao para a Ciencia e Tecnologia, through the Strategic project reference UID/FIS/04650/2013, Ph.D grant SFRH/BD/111720/2015 for Filipe C. Correia and Ph.D grant SFRH/BD/112868/2015 Juliana Marques.

This work focuses on X-ray photoelectron spectroscopy (XPS) and combined Raman and photoluminescence experiments performed on ∼500 nm thick ZnO:Ga films deposited by magnetron sputtering. The substrate bias voltage applied during the deposition was varied between 0 V (grounded) and −120 V in order to study the effect of Ga-doping on the ZnO wurtzite structure of the films and its electrical properties, when using a fixed doped composition of Ga2O3 (4.5 wt.%) in the ZnO sputtering target. XPS analysis revealed that ZnO dominates in all samples, while the Ga amount is the highest (∼2.9 at.%) for a substrate bias polarization of −60 V, diminishing substantially for either decreasing or increasing substrate polarizations. This increase in Ga con centration is responsible for the enhancement of electronic transport properties, resulting in a minimum elec trical resistivity of ∼300 µΩ·cm. Moreover, the atomic layers closer to the surface are deficient in zinc for higher bias, due to the etching effect of Ar+ ions and subsequent Zn re-evaporation. From the Raman experiments, it was observed that the dynamics of the A1 and E1 phonons correlates with the decrease of the electrical resistivity. Photoluminescence studies revealed two broad bands, being one near the ZnO near-band-edge (3.4 eV) and another at higher energies (∼3.6 eV). The band centered at higher energies is more prominent for the case of the more electrically-conductive films, and is ascribed to electron transitions from the conduction band to single ionized oxygen vacancies. The lifetime of the polar-nature longitudinal optical phonons is in the range of 0.1–0.2 ps, which is quite small due to the Fröhlich interactions with gallium dopant atoms and other defects, The authors acknowledge the funding from the following Portuguese institutions Agência Nacional de Inovação (ANI), project reference POCI-01-0247-FEDER-017796 (WinPSC) co-funded by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement, and from the Fundação para a Ciência e Tecnologia (FCT) / PIDDAC through the Strategic Funds project reference UID/FIS/04650/2013. Filipe C. Correia acknowledges the financial support from the Fundação para a Ciência e Tecnologia (FCT) through the Ph.D research grant SFRH/BD/111720/2015.

This paper reports the effect on the electrical and morphological properties of co-doping ZnO thin films with Bi and Al or Ga. To do so, a confocal sputtering geometry was used with a Bi target and two intrinsically doped ZnO:Ga and ZnO:Al targets. By depositing at an intentional heating of 200 °C and applying a post-deposition thermal treatment at 350 °C and 300 °C, for ZnO:Ga,Bi and ZnO:Al,Bi, respectively, electrical resistivity values of 1.3 × 10−3 Ω cm and 4.8 × 10−4 Ω cm were achieved, with an optical transmittance above 80%. The X-ray diffraction data shows that all doped ZnO films have a wurtzite hexagonal structure with preferential crystal growth perpendicular to the (002) plane. The Seebeck coefficient was measured for the ZnO:Al,Bi films, where a maximum value of −48 μV K−1 was registered. The optimized electrical properties were correlated with the preferential crystalline texture along [001] and the corresponding current density applied to the Bi dopant target, J(Bi). ZnO:Al,Bi films present out-of-plane compression stress, which concomitantly increases with J(Bi), due to higher compact volume of unit cell with lower lattice parameter c when compared with the undoped ZnO. By controlling the incorporation of Bi, the deposition temperature and the post-deposition thermal treatment temperature, improvements on the thermoelectric power factor of ZnO:Ga and ZnO:Al thin films can be achieved., ilipe Correia is grateful to the Fundaçao para a Ci ~ ^encia e a Tec nologia for the Ph.D. Grant SFRH/BD/111720/2015. Paulo Salvador is grateful to the Project WinPSC - POCI-01-0247-FEDER-017796, for the research grant, co-funded by the European Regional Develop ment Fund, through the Operational Programme for Competitive ness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. Joana Ribeiro is grateful to University of Minho for the Grant UMINHO/BI/66/2017

The substrate sheet resistance effect in a large area dye-sensitized solar cell (DSC) device is still the main factor responsible for low energy conversion efficiencies. In this work, current collectors made of metal lines were applied by magnetron sputtering on a transparent conducting glass substrate. The introduction of these metal lines enabled a decrease in the sheet resistance from 7.26 Omega.square(-1) to 2.52 Omega.square(-1), by depositing an optimized 1.0 mu m tungsten thick layer on the top of 1.5 mu m thick molybdenum lines. These Mo/W lines withstanded long-term stability when in contact with iodide/triiodide redox couple. Large area dye-sensitized solar cells with 36 cm(2) of active area were assembled and the power conversion efficiency increased from 0.54% to 1.62% when ten metal lines were applied in both electrodes. As a final design, Mo/W lines were only applied onto the counter-electrode and protected with an indium-tin oxide layer; the resulting device showed a power conversion efficiency of 3.43%, compared with the reference efficiency of 2.38%., A. I. Pereira is grateful to Portuguese Foundation for Science and Technology (FCT) through the project SolarConcept (PTDC/EQU-EQU/120064/2010). A. Mendes and L. Andrade acknowledge the European Commission through the Seventh Framework Programme, the Specific Programme "Ideas" of the European Research Council for research and technological development as part of an Advanced Grant under grant agreement no. 321315 (BI-DSC).This work was also partially supported by the projects POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy - UID/EQU/00511/2013) funded by the European Regional Development Fund (ERDF), through COMPETE2020 - Programa Operacional Competitividade e Internacionalizacao (POCI) and by national funds, through FCT and by NORTE-01-0145-FEDER-000005-LEPABE-2-ECO-INNOVATION, supported by North Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)., info:eu-repo/semantics/publishedVersion

The title compound is an organic-inorganic hybrid material of formula (C4H12N2)[FeCl3(H2O)3]Cl2. The single crystal X-ray diffraction investigation reveals that the studied compound crystallizes in the monoclinic system, space group P21/m with the following unit cell dimensions: a = 6.8890(16) A, b = 16.0298(38) A, c = 7.0524(17) A, β = 112.819(5)°, V = 717.8(3) A3 and Z = 4. The crystal structure, refined down to R = 0.05, is composed of [FeCl3(H2O)3] octahedra, piperazinediium cations and chloride anions. The structure cohesion is achieved by hydrogen bonds established between the different entities. The 0D structure can be described as an alternation between organic and inorganic pseudo layers along the crystallographic b-axis. Raman and infrared spectra of the title compound were recorded in the range of 50–4000 and 400–4000 cm-1, respectively. For more reliability, Density Functional Theory calculations were performed in order to check the molecular structure and the vibrational spectra of the investigated molecule in the ground state. Good agreement between calculated structural parameters and single crystal XRD data leading to an appropriate assignment of the IR and Raman observed vibrational modes. The thermal behavior of the compound, studied by TG, showed that the successive decomposition stages of precursor lead to the formation of intermediate phases during heating giving rise to the iron oxide as a final product at 900 °C. The magnetic measurements show that the title compound is predominantly paramagnetic with antiferromagnetic interactions.

The joining of alumina (Al2O3) to &gamma, TiAl and Ti6Al4V alloys, using Ag-Cu sputter-coated Ti brazing filler foil, was investigated. Brazing experiments were performed at 980 &deg, C for 30 min in vacuum. The microstructure and chemical composition of the brazed interfaces were analyzed by scanning electron microscopy and by energy dispersive X-ray spectroscopy, respectively. A microstructural characterization of joints revealed that sound multilayered interfaces were produced using this novel brazing filler. Both interfaces are composed mainly of &alpha, Ti, along with Ti2(Ag,Cu) and TiAg intermetallics. In the case of the brazing of &gamma, TiAl alloys, &alpha, 2-Ti3Al and &gamma, TiAl intermetallics are also detected at the interface. Bonding to Al2O3 is promoted by the formation of a quite hard Ti-rich layer, which may reach a hardness up to 1872 HV 0.01 and is possibly composed of a mixture of &alpha, Ti and Ti oxides. Hardness distribution maps indicate that no segregation of either soft or brittle phases occurs at the central regions of the interfaces or near the base Ti alloys. In addition, a smooth hardness transition was established between the interface of Al2O3 to either &gamma, TiAl or Ti6Al4V alloys.

Nitrogen-doped TiO2 nanoparticles with high specific surface area and photocatalytic activity under visible light were successfully produced using a modified sol-gel method with urea introduced as the nitrogen source. Different synthesis approaches and parameters such as doping temperature and urea to TiO2 molar ratio were tested to examine the best outcome regarding photocatalytic activity for both UV-A and visible light irradiation. UV–vis diffuse reflectance characterization revealed a decrease in band gap from 3.24 to a minimum of 2.79 eV with the N-doping process. The photocatalytic Methylene Blue dye degradation assays suggests that the in troduction of nitrogen in the TiO2 lattice cell can provide a higher efficiency under both UV-A and visible irradiation. The maximum photocatalytic activity was achieved for the nitrogen-doped powders prepared with the lowest urea:TiO2 molar ratio (1.5) as it was the formulation that promoted an enhancement in N-doping and particle specific surface area to 182 m2 g−1 , despite the fact that the highest specific surface area was registered for undoped TiO2 nanoparticles (228 m2 g−1 ). A synthesis step variation was performed to enhance the specific surface area of nanoparticles and consequently the photocatalytic activity. This modification promoted an increase in specific surface area by a factor of ∼5. XPS spectra confirmed a successful introduction of nitrogen in the TiO2 lattice up to 1.5 at.% for optimized powders, which is strongly dependant of the type of synthesis and the amount of dopant species added during the doping process., The authors acknowledge the financial support of the project “NanoPlus Window”, with the reference POCI-01-0247-FEDER-018018, co-funded by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. J. Marques acknowledges the pH.D grant from FCT (reference SFRH/BD/112868/2015). This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID /CTM /50011/2013), fi nanced by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.

Under mode of ultrasonic vibration, the neutral octahedral mononuclear [trans-CuBr2(N ∩ N)2]·3H2O complex with N ∩ N = 2,2-dimethylpropane-1,3-diamine was obtained. The structure of the desired complex was characterized by UV–Vis. spectroscopy, FT-IR, EDX, MS, SEM, TG/DTA and CHN-analysis. The octahedral-structure of the desired Cu(II) complex was proven via XRD single-crystal diffraction and its molecular interactions were computed by Hirschfeld surface analysis. Alcohol (as solvent) and short ultrasonic vibration dose period played a critical role in sonochemistry synthesis of octahedral neutral trans-CuBr2(N ∩ N)2 complex instead of trigonal bi-pyramidal monocation [CuBr(N ∩ N)2]Br one. Due to the Jahn-Teller effect, the complex exhibited a trans bonds elongation along Br-Cu-Br axis originating a distorted-octahedral Cu(II), as revealed by the XRD measurements (Br-Cu = 3.04 A). Therefore, the Solvatochromic behavior of the complex was successfully performed since the trans di-bromide ions are loosely coordinated to Cu(II) center, the change in complex solutions colors by using different solvents which can be detected even by naked-eye supported atypical Jahn-Teller elongation effect formation. TG/DTA and Flynn Wall Ozawa (FWO) isoconversional kinetic methods were applied for the complex to figure out the thermal behavior, kinetic of the ligands de-structured and estimate its Ea/α relation. The complex binding mode to the CT-DNA was examined by UV–vis. spectroscopic, melting curve, CV and viscosity tests. The complex exhibited very strong DNA binding via an intercalation mode of coordination with Kb = 6.5 × 105 value.

[Excerpt] This special issue of Catalysis Today is a compilation of full articles from selected presentations made during the 4th Photocatalytic and Superhydrophilic Surfaces Workshop, PSS2017, which took place in Manchester, UK on the 7th/8th December 2017. There is increasing worldwide interest in (predominantly) titania-based photocatalytic and superhydrophilic surfaces for applications including self-cleaning windows and surfaces, water treatment, anti fogging lenses, antimicrobial surfaces, solar fuels and air purification. In applications such as these, titania requires UV light for activation. Consequently, new visible light activated materials are also subject to considerable industrial and academic R&D. However, there are a multitude of production and testing techniques currently in use, often resulting in conflicting results, hampering greater understanding of the photocatalytic process and the further development of new products. PSS2017 aimed to address issues relating to the production, development and testing of photocatalytic materials by bringing together product end users with academics, industrialists and related professionals from across this field. Subject areas represented included chemical and surface engineering, physics, physical chemistry, catalysis and materials science, clearly indicating the multidisciplinary nature of the field. [...]

The authors regret for the typographical error in the value of the Zn 2p binding energy in some parts of the document. The authors would like to apologise for any inconvenience caused.

The experiment at HASYLAB/DESY was performed within the project I-20180036 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Filipe Correia is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. Grant SFRH/BD/111720/2015 . Joana Ribeiro is grateful to the Project WinPSC - POCI-01-0247-FEDER-017796, for the research grant, co-funded by the European Regional Development Fund (ERDF) , through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. The authors acknowledge the funding from the following institution Fundação para a Ciência e Tecnologia (FCT, Portugal) /PIDDAC through the Strategic Funds project reference UID/FIS/04650/2013. The Spanish Ministry of Economy, Industry, and Competitiveness through the “Severo Ochoa” Program for Centers of Excellence in R&D (SEV-2015-0496), projects No. MAT2017-90024-P (TANGENTS)-EI/FEDER and MAT2015-70850-P (HIBRI2), and the Generalitat de Catalunya through grant 2017-SGR-00488 . M. K. acknowledges the Ph.D. programme in Materials Science from Universitat Autonoma de Barcelona in which she is enrolled., Transparent n-type niobium-doped titanium dioxide thin films (TiO2:1.5 at.%Nb) with pronounced thermoelectric properties were produced from a composite Ti:Nb target by reactive magnetron sputtering. The thin films were comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, optical spectroscopy, electrical conductivity, and thermoelectric measurement techniques. The local structure of the thin films was investigated in detail by X-ray absorption spectroscopy at the Ti and Nb K-edges. A set of radial distribution functions were extracted from the simultaneous analysis of EXAFS data at two absorption edges using the reverse Monte Carlo method. It was found that Nb dopant atoms modify the local environment of the films, but their average structure remains close to that of the anatase phase. This conclusion is also supported by the ab initio simulations of XANES. A very high absolute Seebeck coefficient (S = 155 μV/K) for n-type TiO2 was achieved with Nb doping, yielding a maximum power factor and thermoelectric figure of merit of 0.5 mW m−1 K−2 and 0.18 at a temperature of 300 K, respectively, for a 150 nm thick film. From frequency-domain thermoreflectance experiments, a thermal conductivity value of 1.3 W m−1 K−1 was obtained for the optimized TiO2:Nb film., Fundo Regional para a Ciência e Tecnologia POCI-01-0247-FEDER-017796; Generalitat de Catalunya 2017-SGR-00488; MAT2015-70850-P,HIBRI2; SEV-2015-0496,MAT2017-90024-P; UID/FIS/04650/2013; European Regional Development Fund; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

Niobium doped dititanium trioxide (Ti2O3:Nb) films were deposited on glass substrates, through grid-assisted magnetron sputtering. The Ti2O3:Nb films were characterized by X-ray diffraction (XRD), electrical conductivity and optical properties. Film deposition was carried out in two different substrate bias modes: DC and unipolar pulsed. Results show that the negative-pulsed mode improves conductivity and crystallinity. The XRD results show peaks corresponding crystallographic planes of Ti2O3. No niobium oxide NbxOy peaks were observed, which indicates that niobium oxide if formed, is amorphous, and/or substituted Nb atoms remain in a solid solution within the Ti2O3 structure. It was observed that "as-deposited" Ti2O3:Nb films (without post annealing) are transparent and electrical conductive, with transmittance that reaches 60% in the visible light wavelength despite the considerable thickness of the film and a miminum resistivity of 2x10-2 Ω.cm which indicates that there is potential for application as Transparent Conductive Oxide (TCO)., This study was supported by the Government of the State of Santa Catarina through the FUMDES and FAPESC programs.

The aim of this study is to evaluate the potential use of titanium foil coated with sputtered silver and copper films as a novel brazing filler for joining TiAl alloys. For this purpose, a detailed microstructural characterization of the resulting brazing interfaces was carried out. The development of brazing fillers that allow the joining of TiAl alloys without compromising the service temperature is a fruitful prospect. Brazing experiments were performed in a vacuum at 900, 950, and 980 degrees C, with a dwell time of 30 min. Microstructural characterization reveals that brazing joints can be obtained successfully at 950 and 980 degrees C. The interface consists of a large central region of alpha-Ti with an amount of Al and Ti-Ag compound and thin layers, mainly composed of intermetallic compounds, formed close to the base material. A novel brazing filler consisting of Ti foil coated with sputtered Ag and Cu films inhibits the extensive formation of soft (Ag) zones or coarse brittle Ti-Al-(Cu,Ni) particles. Hence, the need for post-brazing heat treatments for the joining of TiAl alloys was avoided., This research is sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividadeand by national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the project PEst-C/EME/UI0285/2013. The authors are grateful to CEMUP-Centro de Materiais da Universidade do Porto for expert assistance with SEM and EDS.

This study modified the surface of a commercial polyamide membrane with the deposition of TiO2 nanoparticles by the self-assembly method under pressure with high permeability and photocatalytic activity. Changes in membrane characteristics and its performance for photocatalytic properties were evaluated. The results indicated that both membrane hydrophilicity and photocatalytic performance were significantly improved by the presence of TiO2 nanoparticles applied under a pressure of 1 bar. The deposition of the TiO2 particles under pressure was able to maintain the particles on the surface of the membranes and their photocatalytic capacity for three cycles of use. The prepared TiO2 photocatalytic membrane presented a great potential for wastewater treatment and for reuse wastewater systems due its ability to remove methylene blue (MB) dye solution by photocatalytic decomposition and physical separation, O principal objetivo do presente estudo foi modificar a superfície de uma membrana de poliamida comercial com a deposição de nanopartículas de TiO2 pelo método self-assembly sob pressão com alta permeabilidade e atividade fotocatalítica. Mudanças nas características da membrana e seu desempenho nas propriedades fotocatalíticas foram avaliados. Os resultados experimentais indicaram que tanto a hidrofilia da membrana quanto o desempenho fotocatalítico foram significativamente melhorados pela presença de nanopartículas de TiO2 aplicadas sob uma pressão de 1 bar. A deposição das partículas de TiO2 sob pressão foi capaz de manter as partículas na superfície das membranas e sua capacidade fotocatalítica por três ciclos de uso. A membrana fotocatalítica de TiO2 preparada apresentou um grande potencial no tratamento de efluentes e sistemas de reuso devido à sua capacidade de remover o corante azul de metileno por decomposição fotocatalítica e separação física., e Portuguese National Fund, through the FCT - Fundação para a Ciência e a Tecnologia, under the project UID/CTM/00264/2013 and CAPES - Coordenação de Aperfeiçoamento Pessoal de Nível Superior - Agreement CAPES/FCT2014- 2017. The authors thank the support of the researchers of surfaces laboratory of the Centre of Physics of the University of Minho, Portugal by the support analyzes.

Six different shapes of zinc oxide (ZnO) nanostructured antireflective coatings on Si substrate, namely hemispheres, pyramids, motheye-like, cubes, rods and hexagonal prisms, were modeled numerically using finite element simulation, by solving Maxwell wave equation for periodic nanostructure arrays. COMSOL Multiphysics commercial package was used to perform the simulation by adopting the wave optics module. Geometrical parameters including structure size and period were studied in order to obtain better insight on how light and matter interaction is affected by structure geometry. However, among the studied structure geometries, hemispherical ones have the worst optical performance with a maximum reflectance of 45% for a 20 nm hemisphere radius. Pyramidal, motheye and cubic shapes yielded an intermediate optical performance while rod and hexagonal shapes revealed a minimum reflectance (less than 5%) values over a wide range of wavelengths and also showing interesting interference patterns., This research was fully supported by the Jordanian Royal Hashemite Court under the Royal Initiative for Innovative Projects in Nanotechnology.

This work reports the effect of the applied substrate bias and deposition pressure on the bulk composition, electrical and microstructural properties of Gallium-doped Zinc Oxide thin films deposited by DC magnetron sputtering. In-depth Time-of-Flight Secondary Ion Mass Spectrometry and X-ray Photoelectron Spectroscopy studies were endured to determine the Ga content for the varying process conditions. Experiments confirm that the bulk composition of all films is homogeneous and that an optimized Ga doping of 3.9 at.% is obtained for a substrate bias of −100 V and deposition pressure of 0.51 Pa. It was also verified that films with lower electrical resistivity (2.6 × 10−3 Ω∙cm) have a hexagonal wurtzite structure with [001] preferred crystallographic direction. These transparent conductive oxide thin films have potential applications as electrodes in photovoltaics., The authors acknowledge the funding from the following institution Fundação para a Ciência e Tecnologia (FCT, Portugal) / PIDDAC through the Strategic Funds project reference UID/FIS/04650/2013. Filipe Correia is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. Grant SFRH/BD/111720/2015. Paulo Salvador is grateful to the Project WinPSC - POCI-01-0247-FEDER017796, for the research grant, co-funded by the European Regional Development Fund (ERDF), through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement. Joana Ribeiro is grateful to University of Minho for the Grant UMINHO/BI/66/2017.

The aim of this work is to prepare ultraviolet (UV) triggered controlled release of compounds from microcapsule systems (MCs). Polyurethane (PU) and poly(methyl methacrylate) (PMMA) microcapsules were studied with/without chemical functionalization using photocatalytic TiO2 nanoparticles (NPs) on their surface. Once TiO2 nanoparticles are illuminated with UV light (λ = 370 nm), they initiate the rupture of the polymeric bonds of the microcapsule and subsequently initiate the encapsulated compound release, methotrexate (MTX) or rhodamine (Rh), in the present work. The size, polydispersity, charge, and yield of all MCs were measured, being the methotrexate drug release for all systems determined and compared with and without functionalization with TiO2 NPs, under dark, visible light and UV illumination in vitro. Finally, the Rh release was characterized using fluorescence microscopy. The TiO2 NPs size is around 10 nm, as determined by X-ray diffraction experiments. The PU MCs average size is around 60 µm, its electric charge +3.11 mV and yield around 85%. As for the PMMA MCs, the average size is around 280 µm, its electric charge −7.2 mV and yield around 25% and 30% for both MTX and Rh, respectively. In general, adding TiO2 NPs or the encapsulated products to the MCs does not affect the size but functionalization with TiO2 NPs lowers the electric charge. Microcapsules functionalized with TiO2 nanoparticles and irradiated with UV light presented the highest release of MTX and Rh. All other samples showed lower drug release levels when studied under the same conditions., The authors thank the deanship of research at Jordan University of Science and Technology (JUST) for their generous fund (Proposal Number: 161/2016). Juliana Marques kindly acknowledges the funding for her Ph.D grant from the Portuguese institution Fundação para a Ciência e Tecnologia – FCT [SFRH/BD/112868/2015].

Supplementary material available at: http://www.rsc.org/suppdata/c5/ra/c5ra25385c/c5ra25385c1.pdf, Photocatalytic processes based on titanium dioxide (TiO 2 ) nanoparticles have attracted increasing attention in the last decades. However, approaches based on nanoparticles show some drawbacks, in particular due to the need of expensive and time consuming post-treatment of nanoparticles filtration/separation. This hindrance demands the development of immobilized configurations with tailored properties, as an alternative to allow simple recovery of the photocatalytic particles. Thus, this work reports on the development of photocatalytic membranes based on TiO 2 nanoparticles immobilized into a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) membrane and the comparative study of their performance with dispersed TiO 2 nanoparticles. Photocatalytic nanocomposite membranes with a highly porous structure (~75 %) and controlled wettability by NaY addition were successfully produced. These properties were paramount to achieve a methylene blue degradation efficiency of 96 % in 40 min under ultraviolet (UV) irradiation, corresponding to an efficiency loss of just 3 % regarding the TiO 2 nanoparticle assays., This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2014 and PEST- C/QUI/UIO686/2014. P.M. Martins thanks the FCT for grants SFRH/BD/98616/2013. The authors thank financial support from the Basque Government Industry Department under the ELKARTEK Program. SLM thanks the Diputación de Bizkaia for financial support under the Bizkaia Talent program.

Ti-Me binary intermetallic thin films based on a titanium matrix doped with increasing amounts of Me (Me = Al, Cu) were prepared by magnetron sputtering (under similar conditions), aiming their application in biomedical sensing devices. The differences observed on the composition and on the micro(structural) features of the films, attributed to changes in the discharge characteristics, were correlated with the electrical properties of the intermetallic systems (Ti-Al and Ti-Cu). For the same Me exposed areas placed on the Ti target (ranging from 0.25 cm2 to 20 cm2) the Cu content increased from 3.5 at.% to 71.7 at.% in the Ti-Cu system and the Al content, in Ti-Al films, ranged from 11 to 45 at.%. The structural characterization evidenced the formation of metastable Ti-Me intermetallic phases for Al/Ti atomic ratios above 0.20 and for Cu/Ti ratios above 0.25. For lower Me concentrations, the effect of the α-Ti(Me) structure domains the overall structure. With the increase amount of the Me into Ti structure a clear trend for amorphization was observed. For both systems it was observed a significant decrease of the electrical resistivity with increasing Me/Ti atomic ratios (higher than 0.5 for Al/Ti atomic ratio and higher than 1.3 for Cu/Ti atomic ratio). Although similar trends were observed in the resistivity evolution for both systems, the Ti-Cu films presented lower resistivity values in comparison to Ti-Al system., Operacional Factores de Competitividade – and by national funds through FCT – Fundação para a Ciência e a Tecnologia –, under the projects PEST-C/FIS/UI607/2013 and PEst-C/EME/UI0285/2013. J. Borges also acknowledges the support by the European social fund within the framework of realizing the project “Support of inter-sectoral mobility and quality enhancement of research teams at Czech Technical University in Prague”, CZ.1.07/2.3.00/30.0034.

Microcapsules produced by interfacial polycondensation of p-phenylenediamine (PPD) and sebacoyl chloride (SC) were studied. The products were characterized in terms of morphology, mean diameter and effectiveness of dodecane encapsulation. The use of Tween 20 as dispersion stabilizer, in comparison with polyvinyl alcohol (PVA), reduced considerably the mean diameter of the microcapsules and originated smoother wall surfaces. When compared to ethylenediamine (EDA), microcapsules produced with PPD monomer were more rigid and brittle, prone to fracture during processing and ineffective retention of the core liquid. The use of diethylenetriamine (DETA) cross-linker in combination with PPD did not decrease capsule fragility. On the other hand, addition of a small fraction of oleic acid to the organic phase remarkably improved wall toughness and lead to successful encapsulation of the core-oil. Oleic acid is believed to act as a plasticizer. Its incorporation in the polymeric wall was demonstrated by FTIR and (1)H-NMR., This work was funded by FEDER funds through the Operational Programme for Competitiveness Factors (COMPETE), ON.2 – O Novo Norte – North Portugal Regional Operational Programme and National Funds through Foundation for Science and Technology (FCT) under the projects: PEst-C/EQB/UI0511, NORTE-07-0124-FEDER-000026 – RL1_ Energy and PTDC/CTM-NAN/119979/2010. The Bruker Avance III 400 spectrometer is part of the National NMR network and was purchased under the framework of the National Programme for Scientific Reequipment, REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and (FCT). Joana R. Góis acknowledges FCT-MCTES for her PhD scholarship (SFRH/BD/69635/2010).

Microstructural characterization and crystallographic orientation aspects of aluminium doped zinc oxide (ZnO:Al) thin films have been investigated by means of electron backscatter diffraction. ZnO:Al was produced by magnetron sputtering deposition from a ZnO ceramic target containing 2.0 wt% Al2O3 and 0.12 wt% Y2O3. Both top surface and cross-section analysis were performed. The experimental details concerning specific sample preparation procedures for EBSD investigations are presented. Crystalline texture was described by the inverse pole figure (IPF) maps. Strong texture on the basal plane orientation was observed on the analyzed thin film surface. In accordance with these results obtained from top surface investigations, a strong prismatic texture was found in cross-section analysis. From all these analyses a good description and quantification of the three dimensional configuration of the grains and of their crystallographic texture can be proposed., The authors kindly acknowledge the financial support from the Portuguese FCT scientific program for the National Network of Electron Microscopy (RNME) REDE/1511/RME/2005.

Nitrogen-doped titania semiconductor thin films, with photocatalytic properties and a high transmittance in the visible range, have been deposited by unbalanced reactive magnetron sputtering on glass substrates, using d.c. pulsed power supplies. In order to increase the photocatalytic efficiency of the titania coatings the authors optimized the sputtering process, namely by using d.c. pulsed currents for better optimization of reactive gas consumption, and doped the coatings with nitrogen. With this combined and synergistic effect it was possible to enhance the catalysts absorption of visible light, by reducing its semiconductor indirect band-gap. By slightly doping the titania films with 0.7–0.9 at.% nitrogen the photocatalytic performance is ameliorated with almost one order of magnitude. This has been achieved by using nitrogen as a co-reactive gas, together with oxygen, when sputtering from a pure titanium target. The as-deposited thin films on glass are mostly amorphous; however, upon a thermal annealing in vacuum at 500 °C, the crystalline phases of anatase and rutile are developed, being anatase the most prominent polymorph. The photocatalytic performance of the N-doped titania films was evaluated by the decomposition of an organic dye (C.I. Reactive Blue 19) with combined UV/visible light irradiation. Furthermore, a mechanism for the degradation of this dye is proposed. The hydrophilic properties of these films have also been studied by means of water contact angle measurements after varied illumination periods; a minimum contact angle of ∼10° was achieved for optimized wettability conditions.

Forma parte de número especial: Proceedings of the 35th International Conference on Metallurgical Coatings and Thin Films Ti–Si–C–ON films were deposited by DC reactive magnetron sputtering using different partial pressure ratio of oxygen (pO2) and nitrogen (pN2). Compositional analysis revealed the existence of three different growth zones for the films; (I) N/Ti = 2.1 (high atomic ratio) and low oxygen content; (II) 0.76 < N/Ti < 2.1 (intermediate atomic ratio) and (III) N/Ti ≤ 0.12 (low ratio) and high oxygen content. For high N/Ti atomic ratio (N/Ti = 2.1) the XRD pattern exhibits reflections that correspond to a mixture of two different phases: a metallic-like Ti and a fcc NaCl type structure. Its electrical resistivity presents a metallic character and, consequently, has high infrared reflectivity. For the intermediate N/Ti ratio (0.76 < N/Ti < 2.1), the films crystallize in a B1-NaCl crystal structure typical for TiC0.2N0.8. Their FTIR spectra present C–N modes, besides the TiN ones, that indicate a progressive substitution of nitrogen by carbon atoms with increasing oxygen content (and lowering N/Ti ratio). For the highest oxygen content (and lower N/Ti ratio) the presence of the Ti–O–Ti stretching mode shows the formation of highly resistive Ti–O compounds consistent with the semiconductor character of this film. Biofilm formation as well as material cytotoxicity seemed to be related with the presence of the Ti.

Titanium dioxide's self-cleaning effect has been broadly used in textiles, paints, windows, residual water treatment, amongst various other photocatalytic applications. Polymer substrates have found their way in the semiconductor industry as a base layer for flexible electronics, as well as in sensor and actuator applications. The optimum performance of these systems may be affected by dirt adsorbed on its surface, which can also originate mechanisms for the degradation of the polymer. These thin films have been deposited on electroactive poly(vinilidene fluoride) – PVDF – polymer substrates by unbalanced reactive magnetron sputtering. Rutherford Backscattering experiments evidenced that these coatings have a TiO 2 stoichiometry. Raman spectroscopy experiments revealed that the as-deposited coatings on polymer substrates are mostly amorphous, however evidence of anatase and rutile nano-crystalline phases can be found. The photocatalytic behavior of the titanium dioxide coatings was determined by combined ultra-violet irradiation and absorption measurements of a particular dye in the presence of the catalyst. In order to assess the mechanical behavior of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. The stress–strain curves were analyzed and correlated with photocatalytic efficiency along these curves, as well as with the structural data.

This paper focus on the analysis of the interfaces of nanocomposite TiAlN/Mo multilayers by high-resolution transmission electron microscopy (HRTEM). These thin films were deposited by reactive magnetron sputtering, with modulation periods below 7 nm. The structural disorder at the interfaces was probed by the analysis of the X-ray diffraction data, and afterwards correlated with the TEM observations on the cross-sections of the TiAlN/Mo multilayers. For specific deposition conditions, these structures can be prepared with relatively planar interfaces, revealing layer-by-layer growth. For modulation periods below 3 nm the intermixing acts a major role in the degradation of the multilayer chemical modulation.

Pure and Nd-doped TiO 2 thin films were fabricated by reactive d.c. magnetron sputtering at low-temperature from a pure Ti target. The structure of films was analyzed by X-ray diffraction (XRD). In order to study the Nd-doping effect on TiO 2 photocatalytic activity, some films were deposited on microscope glass substrates under a constant total sputtering pressure and using different Nd-doping concentrations. The effect of different Nd-dopant concentrations and its influence on the photocatalytic efficiency has been explored by measuring the photodegradation of rhodamine-B (RhB) aqueous solution under radiation of UV light. It is principally that for comparison between heat treatment and doping process on TiO 2 photocatalytic efficiency (important under the point of view of energy costs related with industrial sputtering techniques), crystalline TiO 2 films were also produced by thermal annealing. It was found that comparing with annealed pure TiO 2 films, Nd-doping do not improve the photocatalytic activity. At the same time, it was observed that there seems to exist a dopant concentration band for optimal photoreactivity. In order to study the effect of the film mechanical strength on photocatalytic activity, fragmentation tensile tests were also done on TiO 2 /PET (polyethylene terephthalate) substrates at increasing applied strains. It was found that increasing the magnitude of the applied tensile strain, pure TiO 2 becomes more photocatalytic efficient.

Titania (TiO2) thin films have been deposited on polymer sheets by magnetron sputtering at room temperature. Previous X-ray diffraction experiments revealed, for a wide range of deposition parameters, that the as-deposited titania thin films are predominantly amorphous; however, Raman scattering experiments revealed small traces of crystalline phases. The photocatalytic behaviour of the titania coatings was determined by combined ultra-violet (UV) irradiation and absorption measurements of a chosen dye (pollutants) in the presence of this catalyst. In order to assess the mechanical behaviour of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. As the system was stretched, cracks transverse to the loading direction developed in the film. The number of cracks increased as the applied strain increased, thus the relation between the measured crack density and the applied strain has been used to characterize the film strength and has also been correlated with the film photocatalytic efficiency. As a result of moderate fissuring on the titania film, it was found that for strain deformations up to 5% the photocatalytic activity is enhanced due to the exposure of more catalyst surface area for the pollutant to be adsorbed and subsequently dissociated upon UV illumination.

This study investigates the functionalization of titanium dioxide nanoparticles on the surface of polymeric microcapsules as a mean to control the release of encapsulated citronella through solar radiation. This allows for the release of a mosquito repellent without human intervention, as the sunlight works as a release activator. The TiO2 nanoparticles were synthetized using a modified sol–gel and hydrothermal method, with a crystallite size of the order of 10 nm and a specific surface area >250 m2/g. Transmission electron microscopy observations enabled the confirmation of the mesoporous structure. The nitrogen doping effect and changes in pH (pH = 3, 6 and 9) of the precursor solution was studied from photocatalytic and photoluminescence experiments. Polyurethane microcapsules were prepared using a modified interfacial polymerization method. The surface topography ofthe microcapsules was observed with scanning electron microscopy, while the release efficiency was quantified using gas chromatography coupled with mass spectroscopy. In-vitro bioassays using live mosquitoes further attested the controlled release repellence effect of these photocatalytic microcapsules by inhibition of these vectors. The results showed that functionalizing the microcapsules with nanoparticles on their surface and then exposing them to ultraviolet radiation effectively increased the output of citronella into the air, repelling the mosquitoes, This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the PTDC/CTM-NAN/119979/2010 project. Juliana Marques acknowledges the FCT supportfor her PhD grant SFRH/BD/112868/2015. The authors would like to acknowledge Dr C. Mateos-Pedrero for the BET surface area analysis.

Titania polycrystalline thin films with high photocatalytic activity were produced by dc reactive magnetron sputtering. X-ray diffraction experiments revealed that the as-deposited films are amorphous and thus unable to deliver an optimum photocatalytic efficiency. By annealing the deposited coatings for 2 h at 500 °C a competitive crystallographic phase growth of anatase and rutile was observed. The anatase titania developed a very high photocatalytic activity. When immersed in a rhodamine B solution and irradiated with ultra-violet light for different periods of time, one could monitor the degradation rate of the dye concentration with time from the decay of its absorption spectra. Several deposition parameters dictate the optimum performance of the titania coatings, such as their relative oxygen and argon partial pressure, cathode current, bias voltage, external magnetic field and post-annealing temperature.

Titanium dioxide is among the few semiconductors that have good chemical/photochemical stabilities and high oxidation power. However, its relatively high band gap makes it only effective when exposed under UV light. It has been found that the addition of transition metals to TiO 2 can improve the photocatalytic activity by UV irradiation and extend its use in the visible region of the electromagnetic spectrum. In this work, the reactive magnetron sputtering method was used to prepare pure and Fe-doped titanium dioxide thin films. The films were deposited onto microscope glass slides and polycarbonate plates at different total pressures and iron-doping concentrations. The morphology of the films was analysed by atomic force microscopy (AFM) and their structure by X-ray diffraction (XRD). The effect of Fe-doping and total sputtering pressure on the photocatalytic activity, was evaluated by measuring the degradation rates of the rhodamine-B (RhB) dye under UV irradiation. The experimental results show that the deposited TiO 2 films on the glass substrate were of the anatase phase with a 〈0 0 4〉 preferred orientation. On contrary, for TiO 2 films deposited on the polycarbonate substrate only an amorphous structure was obtained. The crystallite sizes of the films were 4.1 and 7.1 nm for TiO 2 films deposited at total sputtering pressures of 0.4 and 0.5 Pa, respectively. The iron doped films resulted in the light absorbance shifting to the visible range of the electromagnetic spectrum. In general, iron doping led to a decrease in the photocatalytic activity of TiO 2 films deposited on both substrates. However, the highest photodegradation rates were obtained for films deposited on the polymer substrate under the lower total pressure of 0.4 Pa.

ZrO2/Al2O3 coatings have been deposited by DC reactive magnetron sputtering with a nanolayered structure thickness of 3/3.5, 6/7 and 12/14 nm of each layer. The aim of this work is to study the mechanical properties of the ZrO2/Al2O3 nanolaminated coatings, relate it to with the nanolayered structure, the microstructural and structural properties. The mechanical behaviour of ZrO2/Al2O3 nanolaminated coatings was studied by nanoindentation. Low load tests were performed to study the hardness and Young's modulus after deposition and after heat treatment at 1000 °C. Tests were also performed at higher loads in order to observe the plastic behaviour of the coatings. The adhesion was also studied using scratch test measurements. In the as-deposited condition the hardness has no significant changes. However, after heat treatment it increases for all coatings and reaches 24 GPa for a ZrO2/Al2O3 nanolaminated coatings prepared with 12/14 nm thickness of each layer.

In the last few years a considerable effort has been undertaken in order to optimise the production techniques of thin films and improve their quality. In this work, nanocomposite films resulting from Si additions to a (Ti,Al)N matrix have been prepared by RF and/or DC magnetron sputtering, with deposition rates varying from 0.21 μm/h to 4.6 μm/h. Rutherford Backscattering (RBS) and Electron Microprobe Analysis (EMPA) were used in order to access the chemical composition as well as the density of the films. For samples prepared with low deposition rates (deposited by a combination of RF and DC reactive magnetron sputtering) both symmetric and asymmetric XRD scans showed the development of crystalline phases whose structure is very similar to that of bulk TiN. The peak positions revealed changes of the lattice parameter from 0.420 to 0.428 nm with an increase of Si content dependent on the deposition rate. The lowest lattice parameter corresponds to a Ti–Si–Al–N phase where some of the Si and Al atoms are occupying Ti positions in the f.c.c. TiN lattice, while the highest lattice parameter corresponds to a system where at least a partial Si segregation can be enough to nucleate and develop the Si 3 N 4 phase that forms a layer on the growth surface, covering the (Ti,Al)N nanocrystallites and limiting their growth. As for the (Ti,Al,Si)N crystalline texture evolution, a (111) preferential growth for (Ti,Al)N and for low Si content was observed, while at intermediate Si content the texture changed to (200). With the increase of the Si content there is a corresponding decrease in the size of the diffracting grains. For samples prepared with high deposition rates (DC sputtered samples) High-Resolution Transmission Electron Microscopy (HRTEM) micrographs revealed a columnar growth associated with the f.c.c.-type structure of both phases. Small crystallites with sizes between ±7 and ±10 nm were observed. The use of (Ti,Al) and (Ti,Si) targets, relatively high deposition rates and an alternate deposition resulted in a multilayer of (Ti,Si)N/(Ti,Al)N. This system was produced with modulation periods between 5 and 10 nm, as shown by HR-TEM results, when the samples were grown with a deposition rate between 2 and 4.6 μm/h, respectively. Their average ultramicrohardness can be as high as 50 GPa. The residual stress values for the multilayer system are significantly lower than that of (Ti,Si,Al)N nanocomposite coatings.

This paper reports on the effects of different sputtering deposition process parameters (substrate temperature, sputtering pressure and bias voltage) on the electrical, optical, structural and morphological properties of gallium-doped ZnO (ZnO:Ga) of ~1 μm thick. These highly transparent and conductive films were deposited on glass surfaces by d.c. pulsed magnetron sputtering from a GZO (ZnO(95.5):Ga2O3(4.5)) ceramic target in an argon atmosphere. X-ray diffraction experiments show that all films have a hexagonal wurtzite structure with the [001] preferred crystallographic direction, and themorphology of the films (obtained fromscanning electron microscope analysis) is sensitive to the process parameters. All ZnO:Ga films have an average transmittance above 80% in the visible region, and the lowest electrical resistivity of 3.03 × 10−4 Ω·cm was achieved for the sample submitted to the lowest bias voltage (−40 V), which corresponds to a carrier concentration and a carrier mobility of 6.99 × 1020 cm−3 and 29.49 cm2 V−1 s−1, respectively. A high substrate temperature, high sputtering pressure and lownegative bias voltage (within the range of studied parameters) proved to be very promising on obtaining optimized ZnO:Ga films, ensuring suitable properties for application as transparent electrodes in photovoltaic cells., The authors acknowledge the funding from the Portuguese Innovation Agency (AdI), project reference WinDSC-21539, co-funded by FEDER/POFC.

Titanium dioxide (TiO2) in different forms such as films, fibers or particles are being extensively studied for removal of contaminants from aquatic environments due to its outstanding photocatalytic activity. This work reports the development of TiO2-polyamide 12 electrospun fiber mats. A systematic study on the influence of electrospun processing parameters on polymer fiber morphology was performed. It was observed that the average fiber diameter is mainly influenced by polymer concentration and average fiber diameters between 404 ± 82 nm and 1442 ± 360 nm were obtained. Polyamide-12 (PA-12) was used as a polymer matrix and electrospun with 0, 10 and 20 wt% of TiO2. It was observed that the filler does not change the average fiber diameter, being similar to that observed for neat PA-12 fibers processed under the same experimental conditions. The TiO2 were particles dispensed not only in the bulk of the polymeric matrix but also on the surface of the fibers, especially for the samples with higher filler contents. Neat and nanocomposite electrospun samples show a hydrophobic behavior and a degree of crystallinity of ~25%. The photocatalytic performance of the processed samples was measured by following the degradation capability of a chosen dye, methylene blue (MB). Results show that the nanocomposite samples have a remarkable photocatalytic activity, especially the one with a higher load of TiO2 particles (20 wt%), with all MB being removed from the solution after 100 min., This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/ UI607/2014, and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnol ogico e Brazil). The authors also thank funding from “Matepro eOptimizing Materials and Processes”, ref. NORTE- 07-0124-FEDER-000037”, co-funded by the “Programa Operacional Regional do Norte” (ON.2 e O Novo Norte), under the “Quadro de Refer^encia Estrat egico Nacional” (QREN), through the “Fundo Europeu de Desenvolvimento Regional” (FEDER). PM thanks the FCT for the, SFRH/BD/98616/2013 grant. VS and SLM also thank support from the COST Action MP1206 “Electrospun Nano-fibers for bio inspired composite materials and innovative industrial applications”. VS thanks the EIS Faculty at UOW for the starting grant.

Films resulting from Si additions to TiN matrix were prepared with Si contents in the range 0–19 at.%, using a closed field unbalanced DC magnetron sputtering system. Transmission Electron Microscopy (TEM) analyses revealed the nanocrystalline nature of these coatings, confirming the results of grain size evaluation from X-ray diffraction (XRD) patterns. Nanoindentation tests and scratch tests were carried out for the mechanical characterisation. Regarding the results, the samples show hardness values as high as 45 GPa. Best hardness values were found for Si content in the range 4–10 at.%. Almost all samples showed high critical loads for total adhesion failure, generally higher than 80 N, although the critical load for the first adhesion failure was found to be lower than 20 N for several samples. XRD patterns revealed the presence of only one phase that can be assigned to a cubic B1 NaCl structure, typical for TiN, with a lattice parameter of approximately 0.430 nm. The preferential growth, as a function of Si content, changes from a strong (111) orientation at the lowest Si additions to a weak (200) orientation at the highest Si content. Density values in the range 3.0–3.7 g/cm3 were obtained for most of the samples prepared with deposition rates between 0.5 and 1.1 μm/h, although higher density values were obtained for higher Ti deposition rates, with maximum of approximately 4.7 g/cm3 for the case of samples with low Si content.

(Ti,Al)N/Mo multilayers have been deposited by dc magnetron sputtering on high-speed steel and silicon substrates. Experimental X-ray diffraction (XRD) and computational modelling of these patterns has been carried out to achieve the basics in elucidating their structural properties. The layers were designed with modulation periods of approximately 13 nm, up to a total thickness of 2.8 μm. Residual stress experiments revealed a compressive stress state that prevailed in these structures, ranging from −0.2 to −1.3 GPa. This in turn is in good agreement with the XRD-refined expanded values of the out-of-plane interplanar distances. RBS spectra provided the film composition and a qualitative evaluation of the waviness of the interfaces with increasing substrate bias potential.

Ultra-microhardness, adhesion and residual-stress analysis tests were performed on reactive sputtered deposited TiN/ZrN multi-layers. Hardness values as high as ~3600 Vickers were achieved for this material. Scratch tests of coatings deposited on steel substrates confirmed the existence of different mechanisms associated with total adhesion failure, depending essentially on multi-layer deposition control parameters. Stress-relaxation measurements indicated the compressive nature of these thin films. The inherent mechanical characterisation was broadened regarding the induced contributions from film thickness, total interfacial roughness, number of bi-layers and corresponding modulation periodicity. Complementary analyses with data extracted from structural XRD studies have been undertaken. http://www.sciencedirect.com/science/article/B6TGJ-41M9FXX-14/1/f67cd4e602801eb3439973eebbef7433

TiN/ZrN multilayers were deposited with combined d.c. and RF magnetron sputtering. Experimental X-ray diffraction (XRD) and computational refinement of the latter were undertaken to achieve the basis on which to elucidate the structural properties of the multilayers. Both high-angle and low-angle XRD were used for this purpose. Special attention was given to phenomena occurring at the interface. Therefore, with the assistance of XRD refinement techniques, it was possible to obtain the modulation periodicity, degree of interfacial roughness, strain profile of the individual layers near the interface and lattice mismatch. Intermixing seems to be the mechanism that generates considerable interfacial roughness values (≈11 A).

TiN ZrN multilayers with nominal modulation periods of 8.5, 12.5 and 16.5 nm and total thicknesses ranging between 60 nm and 1.5 μm were prepared by combined DC and RF magnetron sputtering. These coatings were deposited on polished Si substrates. The multilayer period was evaluated by X-ray diffraction (XRD) in the low angle region. Several orders of multilayer reflections are present in these diffraction patterns, exhibiting a pronounced attenuation, which in turn indicates a moderate degree of interfacial roughness. The interface roughness was studied as a function of the number of bilayers and of the modulation period by Rutherford Backscattering Spectrometry (RBS). An increase of the average interlayer roughness with the thickness and with the modulation period was observed.

Transparent and electrically conductive niobium-doped TiO2 thin films have been deposited on glass surfaces by d.c.-pulsed reactive magnetron sputtering from a composite Ti:Nb target, using oxygen as reactive gas. A rapid 1 min annealing at 500 °C in an atomic hydrogen rich atmosphere, obtained by flowing H2 on a Ta filament resistively heated to 1750 °C in vacuum (hot-wire), proved to be very efficient in enhancing the electrical properties of these ~100 nmthick TiO2:Nb thin films. Dark conductivity (σd) and its activation energyweremeasured as a function of (inverse) temperature and the value of σd at room temperature was used to assess the effect of the H2 annealing on the transport properties. A 5-order ofmagnitude increase in electrical conductivitywas observed for optimised treatment conditions at a hydrogen pressure of 10 Pa. A maximum value of σd in the range of ~1.4 × 103 S/cm was attained for optimised conditions, where a level of ~6 at.% of H doping was measured close to the film surface. X-ray photoelectron spectroscopy, elastic recoil detection analysis, Rutherford backscattering and Raman spectroscopies were used to access information of composition and film structure for the explanation of the strong enhancement of the film's electrical conductivity and band-gap widening to 3.45 eV following hot-wire treatments. These thin films can be used as transparent conductive oxide contact layers for photovoltaic applications., The authors acknowledge the funding from the Portuguese FCT COMPETE scientific program.