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Iron‐substituted tricalcium phosphate (Fe‐TCP) (about 1 wt%) coatings are deposited on biodegradable Mg‐Ca alloys to improve their corrosion resistance. Pulsed laser deposition technique is used for coating preparation. The 2 µm thick coatings are uniformly deposited. (Ca+Fe)/P ratio for the Fe‐TCP coatings is close to the stoichiometric value. Coated and uncoated Mg‐Ca alloys are subjected to electrochemical tests to investigate the influence of the coatings on their corrosion resistance in simulated body fluid (SBF). Tafel curves corresponding to coated and uncoated Mg‐Ca alloy samples in SBF show that the most electropositive corrosion potential is reached for the Fe‐TCP‐coated Mg‐Ca deposited at 300 °C. From the obtained and calculated values of the electrochemical parameters it follows that this sample possesses the best characteristics: it has the smallest porosity and the highest protective efficiency in SBF. Equine adipose tissue‐derived mesenchymal stem cells are used for 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide test and osteogenic differentiation study. Microbiology tests are performed with Escherichia coli (E. coli) (Gram−) and Staphylococcus aureus (Gram+) bacteria strains. The Fe‐TCP‐coated Mg‐Ca deposited at 300 °C is characterized by the best cytocompatibility and good ability to inhibit the growth of E. coli and is recommended for biomedical implant applications. [ABSTRACT FROM AUTHOR]

We report on MAPLE deposition of thin films of PEG:PLGA blends. The films were analyzed in terms of morphology, chemical composition, wettability, and optical constants. These properties were particularly discussed in correlation with film thickness. The film thickness was increased by increasing the deposition rate (i.e., laser fluence). This method was effective for fluences up to 1 J/cm, above which the efficiency of the deposition leveled off. Moreover, with increasing fluence above 1 J/cm, important changes in the polymeric films were noticed: the surface roughness increased abruptly (up to ∼200 nm), the polymers lost their chemical integrity and their optical constants underwent significant changes. In addition, surface wettability decreased considerably, water contact angle reaching ∼90°; this was attributed to increased surface roughness and to orientation of the hydrophobic groups toward the surfaces of the films. An alternative method for obtaining thicker films was employed, by prolonging the deposition time while maintaining a constant, relatively low, deposition rate (i.e., fluence). In this case, the properties of the films were significantly less affected. [ABSTRACT FROM AUTHOR]

In this work, matrix-assisted pulsed laser evaporation was applied to achieve gentle deposition of polymer thin films onto surface acoustic wave resonators. Polyepichlorhydrin, polyisobutylene and polyethylenimine were deposited both onto rigid substrates e.g. Si wafers as well as surface acoustic wave devices using a Nd-YAG laser (266 nm, 355 nm, 10 Hz repetition rate). Morphological investigations (atomic force microscopy and optical microscopy) reveal continuous deposited polymer thin films, and in the case of polyethylenimine a very low surface roughness of 1.2 nm (measured on a 40×40 μm area). It was found that only for a narrow range of laser fluences (i.e. 0.1-0.3 J/cm in the case of polyisobutylene) the chemical structure of the deposited polymer thin layers resembles to the native polymer. In addition, in the case of polyisobutylene it was shown that the irradiation at 355-nm wavelength produces deviations in the chemical structure of the deposited polymer, as compared to its bulk structure. Following the morphological and structural characterization, only a set of well established conditions was used for polymer deposition on the sensor structures. The surface acoustic wave resonators have been tested using the Network Analyzer before and after polymer deposition. The polymer coated surface acoustic wave resonator responses have been measured upon exposure to various concentrations of dimethylmethylphosphonate analyte. All sensors coated with different polymer layers (polyethylenimine, polyisobutylene, and polyepichlorhydrin) show a clear response to the dimethylmethylphosphonate vapor. The strongest signal is obtained for polyisobutylene, followed by polyethylenimine and polyepichlorhydrin. The results obtained indicate that matrix-assisted pulsed laser evaporation is potentially useful for the fabrication of polymer thin films to be used in applications including microsensor industry. [ABSTRACT FROM AUTHOR]

We report on the deposition and characterization of hafnium silicate and aluminium silicate thin films for different applications in optics and electronics. Pulsed laser deposition in a controllable oxygen atmosphere was used as a processing technique, with optimized parameters in terms of laser wavelength, laser fluence and oxygen pressure. The thin films were investigated using atomic force microscopy, spectroscopic ellipsometry, UV–VIS spectroscopy and X-ray photoelectron spectroscopy. The morphological investigations evidenced uniform layers with low roughness (in the order of nanometres). The optical investigations revealed that aluminium silicate layers with low roughness and low absorption in the infrared (IR) range can be obtained at high substrate temperatures (600 °C). The behaviour of the silicate thin films with respect to the nanosecond IR laser irradiation revealed that aluminium silicate layers have higher laser-induced damage threshold values in comparison with hafnium silicate. [ABSTRACT FROM AUTHOR]

Tuning the intrinsic structural and stoichiometric properties by different means is used for increasing the green energy production efficiency of complex oxide materials. Here, we report on the formation of self-assembled nanodomains and their effects on the photoelectrochemical (PEC) properties of LaFeO3 (LFO) epitaxial thin films as a function of layer's thickness. The variation with the film's thickness of the structural parameters such as in-plane and out-of-plane crystalline coherence length and the coexistence of different epitaxial orientation—<100>SrTiO3//<001> LFO, <100>SrTiO3//<110> LFO and [110] LFO//[10] STO, as well as the appearance of self-assembled nanodomains for film's thicknesses higher than 14 nm, is presented. LFO thin films exhibit different epitaxial orientations depending on their thickness, and the appearance of self-assembled nanopyramids-like domains after a thickness threshold value has proven to have a detrimental effect on the PEC functional properties. Using Nb:SrTiO3 as conductive substrate and 0.5 M NaOH aqueous solution for PEC measurements, the dependence of the photocurrent density and the onset potential vs. RHE on the structural and stoichiometric features exhibited by the LFO photoelectrodes are unveiled by the X-ray diffraction, high-resolution transmission electron microscopy, ellipsometry, and Rutherford backscattering spectroscopy results. The potentiodynamic PEC analysis has revealed the highest photocurrent density Jphotocurrent values (up to 1.2 mA/cm2) with excellent stability over time, for the thinnest LFO/Nb:SrTiO3 sample, both cathodic and anodic behavior being noticed. Noticeably, the LFO thin film shows unbiased hydrogen evolution from water, as determined by gas chromatography in aqueous 0.5 M NaOH solution under constant illumination. [ABSTRACT FROM AUTHOR]

Due to its physical and chemical properties, the n-type tungsten oxide (WO3) semiconductor is a suitable photoanode for water decomposition reaction. The responses of the photoelectrochemical PEC water-splitting properties as an effect of structural and optical changes of WO3 thin films, as well as the nature of electrolyte solutions, were studied in this work. The WO3 thins films have been obtained by pulsed laser deposition (PLD) on silicon (Si(001)) covered with platinum substrates using three different laser wavelengths. As the XRD (X-ray diffraction) and XTEM (cross-section transmission electron microscopy) analysis shows, the formation of highly crystalline monocline WO3 phase is formed for the film deposited at 1064 nm wavelength and poor crystalline phases with a large ordering anisotropy, characteristic of 2D structures for the films deposited at 355 nm and 193 nm wavelengths, respectively. The photogenerated current densities Jph depend on the laser wavelength, in both alkaline and acidic electrolyte. The maximum values of the photocurrent density have been obtained for the sample prepared with laser emitting at 355 nm. This behavior can be correlated with the coherent crystallized atomic ordering that appear for long distances (10–15 nm) in the (001) plane of the monoclinic WO3 phase structure films obtained at 355 nm laser wavelength. All the samples show poor current density in dark conditions and they are very stable in both acidic and alkaline solutions. The highest photocurrent density value is obtained in acidic solution for the WO3 thin film prepared by 355 nm laser (29 mA/cm2 at 1.6 V vs. RHE (1.35 V vs. Ag/AgCl)). [ABSTRACT FROM AUTHOR]

We report on the investigation of stearic acid-layered double hydroxide (LDH) composite films, with controlled wettability capabilities, deposited by a combined pulsed laser deposition (PLD)-matrix-assisted pulsed laser evaporation (MAPLE) system. Two pulsed lasers working in IR or UV were used for experiments, allowing the use of proper deposition parameters (wavelength, laser fluence, repetition rate) for each organic and inorganic component material. We have studied the time stability and wettability properties of the films and we have seen that the morphology of the surface has a low effect on the wettability of the surfaces. The obtained composite films consist in stearic acid aggregates in LDH structure, exhibiting a shift to hydrophobicity after 36 months of storage. [ABSTRACT FROM AUTHOR]

Film growth of the well-known protein, chicken lysozyme, produced by the dry technique, pulsed laser deposition (PLD), from a compressed powder target has been investigated as a function of the target preparation pressure. PLD is a versatile technique for fabricating high quality films of inorganic materials, but the laser beam will typically produce fragments of molecules in the target and subsequently in the deposited films. We demonstrate that the pressure applied to compact the target prior to the laser irradiation is an important parameter that determines the deposition rate as well as the extent of fragmentation of the deposited molecules. The deposition process was carried out in vacuum using dry targets prepared with compaction pressure in the range 10–160 bar. The residual water in pockets of the lysozyme molecules drives fragments or intact lysozyme out of the target. At the intermediate fluence of 2 J/cm2, the deposition rate of the material (fragments or intact molecules) rises from 3 to 9 ng/cm2 per shot as the compaction pressure increases from 10 to 160 bar. However, the number of intact molecules falls down by almost two orders of magnitude in the same pressure range. This is explained by a stronger cohesion of the target material prepared at higher compression pressure, such that more energy and thus a higher temperature are required for the onset of material ejection. At the highest compression pressure, it means that no intact molecules survive the ejection. The results indicate that there is a pressure range where both a reasonable deposition rate and a considerable fraction of intact molecules in the films can be achieved. These experimental observations are consistent with the results of coarse-grained molecular dynamics simulations, where the fraction of intact lysozyme molecules is observed to vanish as the maximum temperature in the irradiated target increases. • The first systematic investigation of the dependence of the compression pressure of an organic target • High compression of a lysozyme powder target leads to the highest deposition rate. • Only at low compression of the lysozyme target the lysozyme molecules are transferred without fragmentation. • The lysozyme molecules seem to be fragmented at high pressure due to the high temperature needed for ejection. [ABSTRACT FROM AUTHOR]

Abstract This work is meant to respond the challenge of manufacturing osmium targets for nuclear astrophysics experiments using the activation method with alpha particles. In this context, PLD (Pulsed Laser Deposition) was used to prepare osmium targets without specks or wrinkles and with a very well defined and constant thickness. Characterization techniques as RBS (Rutherford Backscattering Spectrometry), AFM (Atomic Force Microscopy), SEM/EDX (Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy) and XRD (X-ray Diffraction) were used to determine accurately the features of the obtained targets. The obtained results reveal that the PLD technique is suitable for the preparation of high quality thin/thick osmium targets. Graphical abstract Image 1 Highlights • Thin and thick osmium targets were prepared using the Pulsed Laser Deposition (PLD) technique. • The thickness, surface morphology, roughness, and purity of targets were investigated by RBS, AFM, SEM/EDX, and XRD. • The targets were successfully used in a nuclear activation experimentat the 9 MV Tandem accelerator in IFIN-HH, Romania. [ABSTRACT FROM AUTHOR]

Thermal behavior studies of several polymers, i.e. polyvinyl chloride (PVC), polyacrylic acid (PAA), and polyaniline (PAni), together with thin film deposition by a MAPLE technique, are presented. Thermal stability studies are important before attempting any laser-assisted processing of such materials, as this provides a better understanding of their molecular behavior, to assess the evolution and dynamics of the deposition. Thin films were grown on silicon substrates by means of matrix-assisted pulsed laser evaporation (MAPLE) using a Nd:YAG laser (266 and 355 nm, 7 ns pulse duration). Above the fluence of ~0.7 J/cm 2 the polymeric films are highly non-uniform due to the transferring of matrix-droplets and/or clusters from the target. At low fluence, typically between 0.1 and 0.5 J/cm 2 , the polymeric films are intact; the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the films. The important question of polymeric molecules integrity in the films with respect to that of the targets is discussed, in relation to their properties, and compared to data available in the literature. [ABSTRACT FROM AUTHOR]

The ability of matrix-assisted pulsedlaser evaporation (MAPLE)technique to transfer and deposit high-quality thin organic, bioorganic,and composite films with minimum chemical modification of the targetmaterial has been utilized in numerous applications. One of the outstandingproblems in MAPLE film deposition, however, is the presence of residualsolvent (matrix) codeposited with the polymer material and adverselyaffecting the quality of the deposited films. In this work, we investigatethe possibility of alleviating this problem by reducing the amountof matrix in the target. A series of coarse-grained molecular dynamicssimulations are performed for a model lysozyme–water system,where the water serves the role of volatile “matrix”that drives the ejection of the biomolecules. The simulations reveala remarkable ability of a small (5–10 wt %) amount of matrixto cause the ejection of intact bioorganic molecules. The resultsobtained for different laser fluences and water concentrations areused to establish a “processing map” of the regimesof molecular ejection in matrix-assisted pulsed laser deposition.The computational predictions are supported by the experimental observationof the ejection of intact lysozyme molecules from pressed lysozymetargets containing small amounts of residual water. The results ofthis study suggest a new approach for deposition of thin films ofbioorganic molecules with minimum chemical modification of the molecularstructure and minimum involvement of solvent into the deposition process. [ABSTRACT FROM AUTHOR]

Highlights: [•] 3D micropatterned PLGA/PU substrates were produced by MAPLE deposition through masks. [•] The substrates were used for regulating the behavior of the keratinocyte stem cells. [•] 3D imaging of substrates and cells was performed by Digital Holographic Microscopy. [•] The cells adhered onto the micropatterned squares and not in the separating channels. [•] The substrates preserved the properties of the keratinocyte stem cells. [Copyright &y& Elsevier]

Abstract: Binary tin oxide–cerium oxide thin films with ceria concentrations in the range 10–30% have been obtained by pulsed laser deposition technique, with or without additional oxygen RF plasma beam assistance. A good preservation of the Ce/Sn atomic concentration and Ce3+ content on the film surface of about 30% was obtained for almost all the investigated conditions of substrate temperature and RF powers. The sharp decrease of the electrical resistance in hydrogen environment at temperatures above 300°C indicates a direct interaction between hydrogen and metal oxides surfaces leading to OH groups formation, as evidenced by XPS measurements. The highest sensitivity (∼40) was attained for the sample with 10% ceria and RF assistance, while the lowest operating temperature (∼250–320°C) was encountered for that with 30% ceria deposited in the presence of RF discharge. [Copyright &y& Elsevier]

Abstract: We present here results on samarium oxide thin films, obtained by pulsed laser deposition and by radio frequency assisted pulsed laser deposition. Three different substrate types were used: silicon, platinum covered silicon and titanium covered silicon. The influence of the deposition parameters (oxygen pressure and laser fluence) on the structure and morphology of the thin films was studied. The substrate-thin film interface zone was investigated; the optical and electrical properties (the losses, dielectric constant and leakage currents) were also determined. [Copyright &y& Elsevier]

Abstract: In this work, we show successful use of matrix-assisted pulsed laser evaporation (MAPLE) for obtaining thin films of PEG:PLGA blends, in the view of their use for controlled drug delivery. In particular, we investigate the influence of the blending ratios on the characteristics of the films. We show that the roughness of the polymeric films is affected by the ratio of each polymer within the blend. In addition, we perform Fourier transformed infrared spectroscopy (FTIR) measurements and we find that the intensities ratios of the infrared absorption bands of the two polymers are consistent with the blending ratios. Finally, we assess the optical constants of the polymeric films by spectroscopic ellipsometry (SE). We point out that the blending ratios exert an influence on the optical characteristics of the films and we validate the SE results by atomic force microscopy and UV–vis spectrophotometry. In all, we stress that the ratios in which the two polymers are blended have significant impact on the morphology, chemical structure and optical characteristics of the polymeric films deposited by MAPLE. [Copyright &y& Elsevier]

Abstract: Zinc(II) coordination compounds may provide a better source for ZnO thin films obtaining, since ZnO was found as the final product of their thermal decomposition. Thin films of zinc benzoate have been obtained on silicon substrates by matrix assisted pulsed laser evaporation (MAPLE) technique, using a Nd:YAG laser working at 266nm. A comparative study of 1% zinc benzoate frozen solution in methanol at different fulences was carried out for 20,000 laser pulses; for the best deposition fluence a double deposition time was employed. Comparative thermal analysis and non-isothermal kinetic investigation of Zn(C6H5COO)2·2H2O dehydration and decomposition was performed. Thin films of ZnO have been obtained by thermal treatment of the MAPLE obtained thin films, according to the thermal analysis and decomposition kinetics of zinc benzoate. The obtained morphologies, before and after thermal treatment, have been investigated by atomic force microscopy (AFM). [Copyright &y& Elsevier]

Abstract: Thin films of [Cd{SSi(O–Bu t )3}(S2CNEt2)]2, precursor for semiconducting CdS layers, were deposited on silicon substrates by Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Structural analysis of the obtained films by Fourier transform infrared spectroscopy (FTIR) confirmed the viability of the procedure. After the deposition of the coordination complex, the layers are manufactured by appropriate thermal treatment of the system (thin film and substrate), according to the thermal analysis of the compound. Surface morphology of the thin films was investigated by atomic force microscopy (AFM) and spectroscopic-ellipsometry (SE) measurements. [Copyright &y& Elsevier]