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The phase stability of (Bi 1-x Y x) 2 O 3 (0.1 ≤ x ≤ 0.275) solid state electrolytes synthesized using the sol-gel method was investigated over prolonged periods under ambient conditions. The cubic polymorph was found to be metastable under ambient conditions, particularly for 0.1 ≤ x ≤ 0.15 where significant cubic-to-tetragonal transformation occurred. Spontaneous minor formation of both the rhombohedral polymorph and a bismuth subcarbonate phase was evident across the doping range but with varied reproducibility. Aging was significantly more prevalent for samples that had only been calcined (at 450 °C) as compared to those that were subsequently annealed (at 750 °C). The more highly substituted annealed materials (0.25 ≤ x ≤ 0.275) were initially phase pure cubic and far more stable, yet some rhombohedral and bismuth subcarbonate phase formation was also seen. Although the initial source of carbon which leads to the formation of the subcarbonate phase is not known at this stage, several suggestions are made. Pelletisation with additional sintering, as well as annealing powder samples under an inert atmosphere, was also shown to enhance the long-term phase stability characteristics of the cubic phase. This is the first longer term (over 2 years) ambient phase aging study of substituted bismuth oxides. [ABSTRACT FROM AUTHOR]

Thermophysical data for liquid slag are required for the optimization and control of metallurgical processes. The density, surface tension and viscosity were measured by employing aerodynamic levitation under contactless conditions. The high-silicate slag (44 and 63 mass-% of SiO 2) of the CaO–SiO 2 and CaO–SiO 2 –Fe 2 O 3 systems (with 5 and 10 mass-% Fe 2 O 3) was investigated under (80% Ar + 20% O 2) gas atmosphere. The temperature ranges were between 800 °C and 2000 °C for the density and 1500 °C–2000 °C for surface tension and viscosity measurements. The influence of the CaO/SiO 2 ratio on the investigated properties and the behavior of Fe3+ ions in high-silicate melts were examined. The density of the CaO–SiO 2 melt was lower than that of the CaO–SiO 2 –Fe 2 O 3 systems. The surface tension of all compositions tested decreased with temperature and showed compositional dependence. The viscosity measured was higher in the Fe 2 O 3 -containing slag. The Raman spectroscopy analyses confirmed the increase in the degree of polymerization with the addition of Fe 2 O 3 for the silicate-rich slag. The formation of a complex anion of a ferric ion and contribution to the silicate network were assumed. The trends observed were related to the structural properties and different interionic bonding. Urbain's viscosity model and FactSage™ 7.3 were applied for the assessment of the experimental data. [ABSTRACT FROM AUTHOR]

Plasticizers such as Bisphenol A (BPA) are highly persistent organic pollutants that are present in raw water as well as in effluents from wastewater treatment plants (WWTP) at levels of parts per trillion (ng L−1) with a high potential to cause carcinogenic and teratogenic effects in the aquatic environment. This research aimed to evaluate the potential of catalytic oxidation to treat BPA with a novel iron boride (Fe 2 B) magnetic nanocatalyst. Several techniques were used for the catalyst characterization: X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning/transmission electron microscopy (SEM/TEM), particle size analysis, and vibrating sample magnetometry (VSM). Experimental results indicated complete BPA degradation with Fe 2 B nanocatalyst where the operating conditions are BPA = 1 mg/L, pH o = 3.0, T = 25 °C, t = 120 min, and Fe 2 B = 0.01 g/L. The investigation of the catalytic mechanism showed that hydroxil radicals in the bulk solution are the dominant reactive species in the BPA degradation. Moreover, the removal efficiency did not decrease after 3 times usage of Fe 2 B nanocatalyst, which reveals its excellent reusability. The acute toxicity results of Fe 2 B indicated that the toxicity depended on the exposure time, the catalyst concentration, and the type of selected test organism. Thus, the laboratory-scale tests resulted that the synthesized Fe 2 B can be used as an effective catalyst for the treatment of BPA. [ABSTRACT FROM AUTHOR]

The development of new materials based on abundant elements, reduced toxicity is today crucial for the next generation of energy device. Titanium-doped hydroxyapatite (TiHA) was tested for the first time as photoanode material for Dye – Sensitized Solar Cells (DSSCs). The chemical composition and energy structure of TiHA powders with increasing titanium content (5 wt%, 10 wt% and 15 wt%) were extensively characterized by surface electron spectroscopies, XPS and UPS. Their compatibility with conventional ruthenium-based dyes molecules was also assessed, producing considerable uptake. TiHA films were produced by screen-printing technique and XRD analyses confirm the presence of apatitic structure. The film properties were completely determined by optical, morphological (FE–SEM) and functional characterizations. Finally, TiHA-based DSSCs were assembled and their photovoltaic performance were assessed. The best efficiency, equal to 0.14%, was obtained for the TiHA containing 15 wt% of titanium. These results open the path for the possible application of doped hydroxyapatite as novel materials for energy conversion systems. [ABSTRACT FROM AUTHOR]

The synthesis of M ′-YbTaO 4 ceramics was carried out by co-precipitation and calcination at 1700 K; phase and chemical purity were confirmed by XDA, XPS, and chemical analysis. The thermal expansion of the crystal lattice was determined by high-temperature diffraction analysis, and the linear and volume thermal expansion coefficients of M ′-YbTaO 4 ceramics were calculated at 298–1173 K. The heat capacity of M ′-YbTaO 4 ceramics was measured using adiabatic methods in the temperature range of 19.6–350 K and differential scanning calorimetry in the range of 316–1326 K. Using the smoothed heat capacity values, the thermodynamic functions of entropy, changes in enthalpy, and reduced Gibbs energy of M′ -ytterbium orthotantalate were calculated. The Schottky-type anomalous contribution in the temperature dependence of heat capacity was estimated. Image 1 • Ceramics M ′-YbTaO 4 synthesis was carried out by co-precipitation and calcination at 1700 K. • M ′-YbTaO 4 sample was investigated by x-ray diffraction, DSC and electron microscopy. • Thermal expansion M ′-YbTaO 4 was measured at 298–1173 K. • Molar heat capacity M ′-YbTaO 4 in the range 20–1326 K was measured. • Thermodynamic functions were calculated. [ABSTRACT FROM AUTHOR]

Currently Mineral Trioxide Aggregate (MTA) is extensively used in Endodontics for Root Canal Treatment. It mainly consists of Portland cement and radio-opacifier agent. In spite of being widely used with success, there are some concerns regarding its properties. The objective of this study was to employ strontium and calcium aluminates to formulate cement pastes with adequate physicochemical and biological properties that overwhelm the handicaps of current Mineral Trioxide Aggregate formulations. First, the desired crystalline phases of calcium and strontium aluminates, i.e. dodeca-calcium hepta-aluminate (Ca 12 Al 14 O 33), C 12 A 7, and tri-strontium aluminate (S 3 Al 2 O 6), S ˇ 3 A , were obtained by Solution Combustion Synthesis and characterized. Then, they were used to formulate different cement compositions varying the wt.-% ratio of C 12 A 7 and S ˇ 3 A (100–0, 80–20, 60–40, 40–60, 20–80, and 0–100) which were characterized with regard to radiopacity. Equivalent radiopacities of 3.1- and 6.0-mm Al were obtained for the cements containing 80- and 100 wt.-% of S ˇ 3 A , both compliant with the requirement of the standard ISO 6876–2012. The cement with 80% of S ˇ 3 A was selected for further studies. Pastes with additions of polyethylene glycol to the mixing liquid (0, 20, 30, and 40 wt.-%) were prepared and studied for workability, setting time, maximum temperature during setting and compressive strength. The cement paste prepared with 30 wt.-% of polyethylene glycol in the mixing liquid (Liquid/Powder 0.39 mL/g) presented good workability, maximum temperature of 33.5 °C, setting time of 60 min, significantly shorter than reported for MTA (140–175 min), and reached highest strength (10.5 MPa) 3 days after mixing. Cement discs were completely coated with a dense apatite layer after 7 days of immersion in simulated body fluid (SBF). The new cement might find application as root canal filler in Endodontics. [ABSTRACT FROM AUTHOR]

Abstract The bioactivity of calcium phosphate (CaP) coatings can be controlled by different CaP phase precipitation and/or addition of foreign ions to their crystal lattice. Cationic substitution of strontium (Sr) into CaP coatings has gained a great attention due to the unique potential of Sr ions on stimulating new bone formation while inhibiting bone resorption. In this study, a novel route was used for producing Sr-substituted calcium phosphate coating on metallic substrates, containing 5 mol%, 10 mol% and 15 mol% Sr concentration, by chemical deposition method. The obtained Sr-substituted calcium phosphate coatings were structurally characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The presence of strontium ions into calcium phosphate phase fostered monetite precipitation, instead of brushite, and this cationic substitution was investigated by Rietveld refinement method. FEG-SEM analysis showed the bioactivity behavior by the precipitation of characteristic bone-like apatite on the 5% Sr-monetite and HA coatings after 14 days of incubation, using McCoy culture medium. The biological performance of the coated surfaces showed that hDPSCs viability was enhanced in the presence of Sr2+ ion concentration up to 10 mol% (p < 0.05) when compared to the uncoated titanium substrates and hydroxyapatite coatings. The results suggested the 5% Sr-monetite as a potential alternative for hydroxyapatite coatings, because of the improved biological responses in this study. [ABSTRACT FROM AUTHOR]

Abstract In this study, monticellite (CaMgSiO 4) ceramic was successfully synthesized by a sol–gel method. The degradation test was evaluated through the weight loss of the CaMgSiO 4 ceramic during immersion in Tris–HCl buffer solution. In vitro apatite-formation ability of the CaMgSiO 4 ceramic was investigated by soaking in the simulated body fluid (SBF), and the deposited hydroxyapatite (HAp) after soaking was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that the CaMgSiO 4 ceramic had a low degradation rate. Furthermore, CaMgSiO 4 ceramic showed good apatite-formation ability, HAp layer constituted by needle-like crystallites was investigated on CaMgSiO 4 ceramic surface after soaking in SBF solution. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings have been extensively studied in the last years in order to increase the operational temperature of the current gas turbines as well as to improve the coating lifetime. Many coating characteristics must be met to achieve these requirements (low thermal conductivity, high thermal fatigue resistance…); therefore, complex systems have been engineered for these purposes. One of the possibilities to optimise the different properties deals with the design of multilayer or functionally-graded coatings where various types of microstructures with different characteristics are combined. One of the most important cause of gas turbines degradation relates to the attack of different type of particles which are suspended in the atmosphere (sand, fly ash…). These solid particles are molten at the operational temperatures and then, the molten salts chemically react with the coating. For this reason, the present research was focused on this type of attack. In the present work, the molten salt attack of various YSZ coatings with multilayer and functionally-graded design was addressed. Two different type of microstructures were specifically combined for this design: the APS coating microstructure obtained from conventional (microstructured) powder and a bimodal structure with nanozones obtained from nanostructured feedstock. Besides, different salts were used to simulate different attack environments (desert sand and volcanic fly ash). Findings show that nanozones act as barrier against the penetration of molten salts toward deeper layer. However, a layer formed by nanozones can detach when the salt attack is too aggressive. Hence, functionally-graded coatings, where two types of microstructures are combined through the whole coating, become ideal to diminish the molten salt attack. [ABSTRACT FROM AUTHOR]

This work investigates the improved CO 2 stability of the partial substitution of scandium (Sc) in the B-site of perovskite ceramic materials thus forming a compound also containing barium (Ba), strontium (Sr), cobalt (Co) and iron (Fe) as Ba 0.5 Sr 0.5 (Co 0.8 Fe 0.2 ) 1−x Sc x O 3-δ . The concentration of Sc in the B-site was varied between 0 and 40 mol%. It was found that perovskite cubic structure was maintained by the substitution with Sc. Further, the cubic cell lattice parameter increased as a function of Sc. However, XRD parameters showed that not all Sc was fully incorporated into the crystal structure of the perovskite, as Sc 2 O 3 phase was also detected. Exposure of as-prepared powders to CO 2 gases resulted in the carbonation reactions occurring at temperatures about 100 °C below those observed for unstable pure BSCF (i.e. no Sc) perovskite. This was attributed to the catalytic effect of Sc, which promoted the carbonation reaction of BSCF-Sc. Subsequently, discs were prepared and exposed to CO 2 gases at 800 °C. The analysis of the discs’ surface showed that the perovskite cubic structure retained 96% of its original values upon CO 2 exposure for the samples loaded with 40 mol% Sc, which then reduced to 32% to samples containing 5 mol% Sc. These results proved to be counterintuitive, as Sc promoted the carbonation reaction at lower temperatures for powders, though enhanced the stability of disc exposed to CO 2 atmosphere. Further analyses of the discs by scanning electron microscopy revealed images containing a rich carbon layer, as a passivation carbonation layer, which protected the remainder of the bulk perovskite structure in the disc. [ABSTRACT FROM AUTHOR]

In this study, tuning of the photoelectrochemical (PEC) water splitting activity from UV to visible region was achieved on RF magnetron sputtered TiO 2 thin films grown under various Ar ion-beam energies (0, 60 and 110 eV). We propose a new strategy of energetic Ar ion-beam projection towards the substrate surface during the film growth. The resulting TiO 2 films were decorated with silver (Ag) nanoparticles for efficient plasmon-enhanced PEC water splitting activity under visible light illumination. Firstly, the ion-beam-energy induced a well-defined anatase TiO 2 (101) phase with improved crystallinity, which is key factor responsible for the enhanced PEC activity. Interestingly, XPS studies revealed the presence of Ti 3+ states along with the Ti 4+ ones, which sensitively influence the UV and visible light absorption. Furthermore, AFM images revealed rough surface topography of the films, which is highly desirable for large area exposure to the electrolyte. In addition, the UV–vis transmittance spectra showed a stronger red shift in the optical absorption edge and a reduced band gap, which are crucial factors for charge carrier generation. Studies on Ag nanoparticles decorated TiO 2 films show that, due to the transfer of surface plasmon energy from the Ag nanoparticles to TiO 2 , efficient visible light water splitting activity was achieved. This is about five times higher than that observed for TiO 2 films under UV light. Comprehensively, this novel approach could pave the way for efficient visible-light-driven PEC water splitting activity. [ABSTRACT FROM AUTHOR]

Experimental phase equilibrium data for the Cu-O-Al 2 O 3 -MgO system is required to improve the performance of MgAl 2 O 4 -containing refractories and slagging in non-ferrous smelting. In this work, the phase relations of MgAl 2 O 4 in the Cu-O-Al 2 O 3 -MgO system were studied experimentally in air within a temperature range of 1100–1400 °C using the equilibration and quenching method. The chemical compositions of the phases in the quenched samples were determined using electron probe microanalysis (EPMA). Less than 1 wt% of Al 2 O 3 or MgO were found in the oxide liquid phase, whereas the solid MgAl 2 O 4 and MgO phases contained up to 23 wt% and 30 wt% of ‘Cu 2 O’, respectively. Discrepancies between these results and the corresponding calculated values generated by the MTDATA 6.0 software and Mtox database Version 8.2 ranged from 3 wt% to 19 wt%. The results of this work indicate that the MgAl 2 O 4 spinel is chemically stable in the presence of a CuO x -rich liquid under the conditions studied. [ABSTRACT FROM AUTHOR]

Two types of thermally durable and heat-resistant enamel coatings were applied to steel alloys. Three-layer TiO 2 -SiO 2 sol-gel films were grown by a dip-coating method on an enamelled metal alloy to maintain and protect their properties from undesired environmental impact. The enamel coatings withstood 6000 h at 600 °C, retaining their colour while staying hard and adhering firmly to the metal surface. A three-layer sol-gel coating improved the chemical resistance of the enamelled metal by 6% (0 h), 29% (3000 h), and 28% (6000 h) at 600 °C. Throughout the whole treatment at 600 °C, the enamel coatings maintained their microhardness and even increased it from 3.6 to 4.4 GPa. [ABSTRACT FROM AUTHOR]

Here we present an easy-reproducible microwave-assisted hydrothermal route for preparing pure nanocrystalline CeO 2 films. The produced materials were characterized using a wide range of techniques (X-ray diffraction, field emission gun scanning electron microscopy, Raman spectroscopy) to understand the synthesis dependent changes in crystallographic structure, and crystallite size. Raman and X-ray diffraction techniques revealed that the films were free of secondary phases and that they crystallize in the cubic structure. The observed hydrodynamic particle size larger than the crystallite size confirms the aggregation phenomenon. Gas sensing measurements have been carried out to rationalize the type and number of surface adsorbed groups and overall nanostructure. Electrical conductance variations, owing to gases adsorption onto semiconductor oxide films surfaces, were observed in this work. Chemiresistive CeO 2 film properties depend on the intergranular barrier heights and width. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of surface treatments on the roughness and bond strength of dental materials containing MDP to zirconium oxide ceramic. Forty square-shaped zirconium-oxide ceramic blocks (Lava Zirconia, 3M-ESPE) were treated as follows: (CT) polished only; (SB) sandblasting (110 µm aluminum oxide particles) or (SC) silica coating (110 µm particles). Roughness of treated surface was measured using a profilometer (Ra) and by atomic force microscope (AFM). Two resin luting agents were used after silane application: self-adhesive (Rely X U200, 3M-ESPE) and dual cure (Rely X Ultimate, 3M-ESPE). The samples were submitted to microshear bond strength test. The failure analysis was performed. Data were submitted to ANOVA and Tukey test (α=0.05). Bond strength results ranged from 20.44 (CT+Ultimate) to 34.37 MPa (SC+U200) after 24 h and from 12.03 (CT+Ultimate) to 27.44 MPa (SC+U200) after 12 months of storage with SC statistically superior to the other treatments. Mean values of roughness varied from 0.07 (CT) to 0.85 µm (SC). The both resin luting agents showed similar results to all surface treatment groups. Silica coating provided the best treatment of the ceramic surface. [ABSTRACT FROM AUTHOR]

Pencil-like tetragonal vanadium dioxide has been synthesized via one-step hydrothermal treatment. The compounds were analyzed through X-ray powder diffraction; scanning electron microscope and X-ray photoelectron spectroscopy (XPS). The optical properties of the as-synthesized material were studied by UV–visible diffuse reflection spectroscopy and room temperature photoluminescence. Thin films of VO 2 (R) deposited on ITO substrates were electrochemically characterized by cyclic voltammetry (CV). The voltammograms show a reversible redox behavior with a doping/dedoping process corresponding to reversible cation intercalation/de-intercalation into the crystal lattice of the pencil. This process is easier in propylene carbonate than in aqueous solvent. It is also easier for the small Li + cation than larger ones, Na + and K + . This is attributed to a probable presence of one tunnel cavities in the structure of VO 2 (R). The good electrochemical property of the VO 2 (R) is attributed to its unique ultralong nanopencils structure with a good structural stability. [ABSTRACT FROM AUTHOR]

Phase relationships of the Cu–O–ZnO system in equilibrium with air ( P O2 =0.21 atm) and metallic copper (in pure argon) have been studied for the first time using equilibration/quenching/EPMA techniques. In this study, we quantified the phases in equilibrium with air in the temperature range 1095–1500 °C and represented the equilibria by the pseudo-binary phase diagram (Cu 2 O–ZnO). The diagram has one simple eutectic reaction with two primary phases of cuprite (Cu 2 O) and zincite (ZnO), and the binary eutectic point was found to be 1098±2 °C with 0.10±0.01 mol fraction of ZnO. There were three phases Cu 2 O+ZnO+liquid copper or ZnO (Cu 2 O)+liquid oxide+liquid copper coexisting with each other in the temperature range 1205–1300 °C, when the system was equilibrated with metallic copper. Isothermal ternary phase diagrams (Cu–O–ZnO) were used to present the results of the experiments at Cu saturation. The eutectic point of the Cu saturated system was determined to be 1208±2 °C and 0.03±0.01 mol fraction of ZnO. Results were compared with the phase diagrams calculated by MTDATA 5.10 and its Mtox 7.0 database. The differences between the experimental data and the computational phase boundaries were significant and the system properties require a re-assessment. [ABSTRACT FROM AUTHOR]

Various CuO nanostructures, including spherical, flower-like, cross-like, leaf-like, and elliptical structures, were obtained via a sodium phosphate (Na 3 PO 4 )–assisted hydrothermal route with CuSO 4 and NaOH as the copper and alkali sources, respectively. The presence of Na 3 PO 4 is vital for the formation of various CuO nanostructures. The morphology of the CuO nanostructures is significantly influenced by the feeding concentration of the NaOH solution. The catalytic activity of the CuO products on the thermal decomposition of ammonium perchlorate (AP) was characterized by differential scanning calorimetry (DSC). Results showed that the addition of CuO nanostructures could dramatically decrease the high decomposition temperature of AP, thereby demonstrating their excellent catalytic activity for the thermal decomposition of AP. [ABSTRACT FROM AUTHOR]

In this work, the ZnO–Co 3 O 4 particles obtained by high energy milling were evaluated in the photocatalytic degradation and adsorption of Rhodamine B dye. The photocatalytic tests were executed under UV-C radiation and the effects of the dye adsorption on the materials surface were assessed through tests in dark room, both monitored by ultraviolet–visible absorption spectroscopy (UV–vis). Infrared absorption technique (FTIR) was performed during the photocatalytic process to evaluate the formation of organic subproducts throughout the reaction. Chemical Oxygen Demand (COD) was carried out for all the samples in order to investigate the presence of residual organic matter after the photocatalytic tests. Results indicated that the Rhodamine B dye was totally decomposed in the presence of milled particles after 90 min, following different rates of degradation. Photocatalytic activity was not observed to the Zn 0,95 Co 0,05 O solid solution submitted to thermal treatment. The FTIR technique indicated that there were no detectable organic subproducts after the reaction and the COD analysis demonstrated a large reduction of organic matter after photocatalytic process. The powders milled during 10 h in wet medium presented the best results of dye degradation due to the highest reduction of particles size among the assessed samples. [ABSTRACT FROM AUTHOR]

This investigation reports a facile surfactant-free synthesis of zinc oxide (ZnO) nanostructures with the aid of zinc nitrate as a starting reagent through a spontaneous solution–solution transfer of ammonia vapor. It also reports their potentials in photocatalytic applications. The obtained samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, and energy dispersive X-ray (EDX), Fourier transform infrared (FTIR), and photoluminescence (PL) spectroscopies. Moreover, the effects of different reaction conditions such as precursor concentration and reaction time on the morphology, particle size, and chemical structure of the product were investigated using SEM and XRD analyses. The efficiency of ZnO nanostructures as photocatalysts for the decolorization of rhodamine-B and methylene blue was also evaluated under ultraviolet light irradiation. [ABSTRACT FROM AUTHOR]

The possibility of a carbothermic reaction between alumina and carbon is discussed based on thermodynamic calculations. A thermodynamic assessment of the Fe–Al 2 O 3 –Al corner of the Al–Fe–O system was done, and an interaction parameter of the metallic liquid phase was derived to model the solution of aluminium and oxygen in the ternary system. The derived dataset was used to calculate two experimental setups: (1) Fe–Al 2 O 3 –12.9 mass%C at 1550 °C under argon atmosphere as found in the literature and (2) the possible interface reaction between Fe–Al 2 O 3 –30 mass%C at 1650 °C. Interface reactions between Al 2 O 3 –30 mass%C and Al-killed steel 42CrMo4 at 1650 °C were studied experimentally using a steel melt-casting simulator. Large particles of exogenous alumina were found on a thin layer of alumina on top of the refractory material. The formation of an in situ-formed alumina layer can be explained thermodynamically by the partial dissolution of alumina and carbon in the iron melt at the interface and the reprecipitation of alumina at the filter surface. [ABSTRACT FROM AUTHOR]

The thermal stability of Li 1+x Ni 0.5 Mn 0.5 O 2 cathode materials in contact with carbon and in the course of carbon coating by pyrolysis of various carbon precursors in argon is studied. XRD patterns of Li 1+x Ni 0.5 Mn 0.5 O 2 –carbon mixtures demonstrate the first traces of phase decomposition at 600 °C while corresponding TG curves show at the significant interaction between components at T >400 °C. Similar interaction of complex oxide with polyethylene glycol pyrolysis products causes the complete deterioration of the layered compound. The first stage of this deterioration is a systematic increase in cation disorder between A and B sublattices of the hexagonal ABO 2 structure. However, the pyrolysis of polyvinyl alcohol at 350 °C results in the formation of nanostructured carbon film. The analysis of as-obtained Li 1+x Ni 0.5 Mn 0.5 O 2 –carbon composites by Raman spectroscopy shows that the linear structure of polyvinyl alcohol promotes the domination of sp 2 forms of carbon in the pyrolysis products while the thermolysis products of cross-linked polymer contain mostly sp 3 -carbon. [ABSTRACT FROM AUTHOR]

Given the recent reports pertaining to novel optical properties of ultra-small quantum dots (QDs) (r<2nm), this nanomaterial is of relevance to both technology and science. However it is well known that in these size regimes most chalocogenide QD dispersions are unstable. Since applications often require use of QD dispersions (e.g. for deployment on a substrate), stabilizing these ultra-small particles is of practical relevance. In this work we demonstrate a facile, green, solution approach for synthesis of stable, ultra-small ZnO QDs having radius less than 2nm. The particle size is calculated using Brus' equation and confirmed by transmission electron micrographs. ZnO QDs reported remain stable for >120 days in ethanol (at ~298-303K). We report digestive ripening (DR) in TEA capped ZnO QDs; this occurs rapidly over a short duration of 5min. To explain this observation we propose a suitable mechanism based on the Lee's theory, which correlates the tendency of DR with the observed zeta potentials of the dispersed medium. To the best of our knowledge this is the (i) first report on DR in oxide QDs, as well as the first direct experimental verification of Lee's theory, and (ii) most rapid DR reported so far. The facile nature of the method presented here makes ultra-small ZnO readily accessible for fundamental exploration and technologically relevant applications. [ABSTRACT FROM AUTHOR]

Abstract: WO3 nanorods have been synthesized with the aid of p-aminobenzoic acid (PABA) through a facile hydrothermal method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption–desorption. The results of XRD and N2 adsorption–desorption showed that the sample was hexagonal phase with a large surface area of 48.3m2 g−1. The TEM result indicated that the as-prepared nanorods had a diameter of 20–50nm and lengths of several microns. Compared to the commercial WO3 powders, the WO3 nanorods exhibited a higher adsorption activity for Rhodamine B (RhB) and a higher catalytic performance for the synthesis of adipic acid. The results demonstrate that the WO3 nanorods have excellent potential applications for the removal of RhB and the synthesis of adipic acid. [Copyright &y& Elsevier]

Abstract: A ternary composite photocatalyst system was prepared in a simple impregnation–pyrolysis process. In the photocatalyst system, multiwalled carbon nanotubes (MWNTs) acted as a catalyst and carrier, CuO and Cr2O3 acted as a co-catalyst and/or charge transferring site, and eosin Y acted as a sensitizer. Under visible light irradiation, activity of hydrogen evolution over the system (CuO/Cr2O3–MWNTs–eosin Y) was higher than that of CuO or Cr2O3 loaded MWNTs–eosin Y. It was demonstrated that simultaneous loading of CuO and Cr2O3 was vital to achieve the high activity. [Copyright &y& Elsevier]

Abstract: In this paper copper selenide nanostructures were synthesized via a simple hydrothermal method based on the reaction between copper salt and SeCl4 in water. The reduction reaction of SeCl4 to Se and then Se2− was carried out by three types of reductants: N2H4.H2O, KBH4, and metallic Zn. Different compositions of copper selenides were obtained by changing the molar ratio of the precursors. At the temperature of 120°C for a 12h period of time, when the molar ratio of Cu/Se is 1:1 or 2:1, the product is pure and found to be CuSe and Cu1.8Se, respectively. A mixture of the different phases of copper selenides is obtained by making use of 1:2, 3:2 and 3:1M ratios between Cu and Se. With an increasing reaction temperature up to 210°C, the mixture of Cu3Se2 and CuSe is prepared from 1:1M ratio of precursors. The effects of copper salt, surfactant, amount of hydrazine, reaction time and temperature on the morphology and particle size of products are also investigated. The synthesis can be performed conveniently and safely. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. Photoluminescence (PL) is used to study the optical property of copper selenides. [Copyright &y& Elsevier]

Abstract: Indium tin zirconium oxide (ITZO) films were deposited by a co-sputtering technique with ITO and zirconium targets. The stability and corrosion behavior of films in simulated environments were studied on account of microstructure and optical–electrical properties. The results show that ITZO films possess a better crystalline structure and optical–electrical properties. Zirconium-doping changes the preferred orientation of ITO films, and ITZO films under the optimum parameters have sheet resistance of 10Ω/sq and transmittance of above 85%. According to the polarization measurements and the relative resistance change of the films in simulated environments such as acidic climate, oceanic climate and industrial climate, the doping films show better chemical and thermal stabilities than ITO films. Besides the influence of crystal structure, the better stability of zirconium oxide can improve the chemical and thermal stabilities. ITZO films have better electrical stability and chemical antcaustic properties, and the films could find more extensive applications. [Copyright &y& Elsevier]

Abstract: Animal flour ash, rich in phosphorous, calcium and alkaline oxides, has been used to formulate (i) controlled-release fertilizers, since they manage to release the nutrient elements (P, K) at a low rate, and (ii) bioactive glasses. (i) Four formulations were tailored using different amounts of animal flour ash (35–48wt%), potassium carbonate (10–25wt%) and a fixed amount of glassy sand (40wt%) in order to get glasses and glass-ceramics. The materials were characterised from a chemical (XRF), crystallographic (XRD) and microstructural (SEM/EDS) point of view. Moreover, in order to check the ability to release the macro- and micro-nutrients, tests were conducted to determine the kinetics of glass dissolution in different media (2% citric acid solution, 1% hydrochloric acid solution and ammonium citrate solution). The results obtained allowed to confirm all samples show a very low solubility in water (less than 1%) and high values (>40%) of P, Ca, K and Na in the other media. (ii) The rich content of phosphorous and calcium oxides makes the animal waste-derived ash a potential low-cost raw material to produce bioactive glasses. The analysis was focused on a bioactive glass, named BG_Ca, whose composition comes from the standard Bioglass® 45S5, got by increasing as much as possible the CaO content to combine a controlled behaviour during processing and a good apatite-forming ability in a simulated body fluid (SBF). This preliminary investigation shows that animal flour ash is a versatile material, which may be successfully used for several applications as various as the production of fertilisers and the preparation of bioactive glasses. [Copyright &y& Elsevier]

Abstract: Beihai area (China) has about 500 million tons kaolin reserves with potential applications in ceramics, paint, plastic and rubber-filler industries, but unlike the Brazilian kaolin, it is not good in paper-coating industry. In order to understand the differences between Chinese (Beihai) and Brazilian kaolin, their individual physicochemical properties, morphologies, crystal structures, and surface characteristics were systematically investigated and compared. The results showed that the viscosity concentration, specific surface area and zeta potential of Brazilian kaolin were higher than those of Beihai kaolin. SEM and TEM images revealed that Brazilian kaolin had more regular particle shape, smoother surface and larger diameter–thickness ratio than those of Beihai kaolin. Moreover, XRD and TG/DSC analyses exhibited that Beihai kaolin was low ordered kaolinite with lower value of Hinckley index, average flake thickness along c-axis and endothermic peak temperature as compared to Brazilian kaolin. Furthermore, the crystal structures refined by the Rietveld method of Beihai kaolin showed a greater distortion of [SiO4] tetrahedron than that of Brazilian kaolin. It can be concluded that low viscosity concentration, low degree of order, and irregular particle shape of Chinese (Beihai) kaolin are the reasons why it is not suitable for use in the paper-coating industry. [Copyright &y& Elsevier]

Abstract: CuO nanorods have been prepared through a facile microwave-hydrothermal method with the aid of polyethylene glycol 400, ethylene glycol and urea. The X-ray diffraction and transmission electron microscopy results showed that the prepared CuO nanocrystalline had a rod-like shape with diameters of 15–20nm and the average length of 80nm. Compared with commercial CuO powder, the CuO nanorods showed an enhanced catalytic activity for the synthesis of sodium humate and the degradation of Rhodamine B. The yield of sodium humate catalyzed by CuO nanorods was 75.78%, which was higher than that of the commercial CuO powder (52.8%). In addition, the CuO nanorods showed a relatively faster degradation rate of RhB. The CuO nanorods prepared by this facile method demonstrated their potential applications in the field of catalysis. [Copyright &y& Elsevier]

Abstract: Rod-like N-doped TiO2/Ag composites were successfully synthesized by a modified sol–gel method, without adding any surfactants. The entire preparation differs from the traditional sol–gel synthesis of TiO2 that the reaction can get controlled by adjusting the flow speed of water vapor and NH3. Characterization results show that as-prepared samples were uniform nanorods with an average length of ca. 3µm and a cross section diameter of ca. 150nm. The rod-like structure was formed during the annealing process. A possible mechanism was proposed to illustrate the formation of rod-like Ag–N–TiO2. The degradation of methylene blue performed under visible light with the prepared nanorods as the photocatalyst demonstrated the photocatalytic activities of TiO2 can be improved by the synergistic effect of N doping and Ag modification. In addition, as-prepared TiO2-based photocatalyst exhibits a significantly enhanced photo-chemical stability after 5 catalytic cycles mainly due to the rod-like morphology. This indicated that they have some potential value in practical application. [Copyright &y& Elsevier]

Abstract: Innovative metallic glazes for porcelain stoneware tiles, containing stainless steel and a special Ni-based alloy (NiCoCrAlY, commonly used as bond coating material in thermal barrier coating systems on Turbogas superalloy components), have been studied. These new products, called “metallic composite glazes” (MCGs), showed different aesthetic properties than usual lustres or metallic glazes. After heating, the surfaces of these innovative glazes did not display any interesting behaviour, but, after polishing, a particular metallic aesthetic effect has been found. These new glazes can be described as composite materials made of a glass matrix reinforced with metal particulates. A deep characterisation of metallic powders and MCGs was performed by using several techniques. The glazes containing the NiCoCrAlY powders manifested the best aesthetic, microstructural, thermal and chemical properties. [Copyright &y& Elsevier]

N-doped ZnO/Ag nanocomposites were rapidly synthesized by a deflagration method within tens of seconds, using urea as fuel and citric acid as vesicant. Characterization results showed that the samples were nanoparticles with an average size of about 15nm. Most of Ag existed in the form of metallic Ag (0), and N was doped into the composite in the form of acceptor impurities. Compared with pure ZnO, the N-doped ZnO/Ag nanocomposites possessed a remarkably enhanced catalytic efficiency on the thermal decomposition of ammonium perchlorate. This is particularly true for the sample containing 4.0% Ag as it offered the best catalytic performance and reduced the final decomposition temperature of AP to 290°C from 453°C. The mechanism showed that the high decomposition rate of AP was due to N doping and Ag modification being able to transfer efficiently electrons from ClO4 − to NH4 + in ammonium perchlorate. [ABSTRACT FROM AUTHOR]

Abstract: Montmorillonite clay from a natural deposit was processed to remove impurities and later submitted for thermal and chemical treatments. The sample was first subjected to a thermal treatment at 400°C, for 1h, to remove organic components. The chemical treatment was conducted first by using an acid attack with nitric acid and sulfuric acid, then, adding sodium acetate in ethylene glycol clay dispersion, and finally the clay was dispersed in xylene with subsequent addition of silane, N-(b-aminoethyl)-g-aminopropyiltrimethylsilane. The combined thermal and chemical treatment was found to have a significant effect on the final chemical composition of the nanoclay. X-ray diffraction patterns suggested that the combined thermal and chemical treatment resulted in increased interplanar distances, thus favoring exfoliation of the clay lamellae, which was also confirmed by SEM images. Fourier transform infrared (FTIR) spectroscopy analysis suggested that the combined thermal and chemical treatment resulted in removal of water from the montmorillonite, without any modification or destruction of the clay structure. Thus, the combination of thermal and chemical treatments proposed in this work may be a promising approach to process montmorillonite intended for the production of advanced materials. [Copyright &y& Elsevier]

Abstract: PEI was used as dispersant for ZrB2 and SiC powders in water. The dispersion behavior of ZrB2 and SiC in water was studied by zeta potential measurements, particle size distribution measurements and interparticle interaction calculations. Well-dispersed ZrB2 and SiC aqueous suspensions were obtained using 0.6wt% PEI at pH 6. The rheological behavior of ZrB2–SiC aqueous suspensions was also investigated. Finally, a high solid loading (52vol%), low viscosity (980mPas at 100s−1) ZrB2–SiC aqueous suspension was successfully prepared. [Copyright &y& Elsevier]

Abstract: The photocatalytic property of titanium dioxide is well known and is responsible for its antimicrobial activity. The present study is focused on the understanding of enhanced antimicrobial property of Eu–Ag codoped TiO2 surfaces, which were prepared using the sol–gel method. After exposing Eu–Ag codoped TiO2 surfaces to Pseudomonas aeruginosa, the microbes attached on them were characterized by total viable counts, epifluorescence and Raman microscopic experiments. These techniques confirmed the effective reduction of microbial attachments on Eu–Ag codoped surfaces when compared to the control and Eu doped TiO2 surfaces. The reason was that the co-dopants favored the transformation of anatase/rutile mixed phase and led to the increase in photocatalytic activity of the Eu–Ag codoped TiO2 surfaces. Also, the metallic silver on TiO2 surface enhanced the photoactivity by accelerating the transport of photogenerated electrons to oxygen molecules, preventing the electron–hole recombination and facilitating the activity of codoped surfaces. [Copyright &y& Elsevier]

Abstract: This paper reports on the composition and flow rate of outlet gas and current density during the reforming of CH4 with CO2 using three different electrochemical cells: cell A, with Ni−GDC (Gd-doped ceria: Ce0.8Gd0.2O1.9) cathode/porous GDC electrolyte/Cu−GDC anode, cell B, with Cu−GDC cathode/ porous GDC electrolyte/Cu−GDC anode and cell C, with Ru−GDC cathode/ porous GDC electrolyte/ Cu−GDC anode. In the cathode, CO2 reacts with supplied electrons to form CO fuel and O2− ions (CO2+2e−→CO+O2−). Too low affinity of Cu cathode to CO2 in cell B reduced the reactivity of the CO2 with electrons. The CO fuel, O2− ions and CH4 gas were transported to the anode through the porous GDC mixed conductor of O2− ions and electrons. In the anode, CH4 reacts with O2− ions to produce CO and H2 fuels (CH4+O2−→2H2+CO+2e−). The reforming efficiency at 700−800°C was lowest in cell B and highest in cell A. The Cu anode in cells A and C worked well to oxidize CH4 with O2− ions (2Cu+O2−→Cu2O+2e−, Cu2O+CH4→2Cu+CO+2H2). However, a blockage of the outlet gas occurred in all the cells at 700−800°C. The gas flow is inhibited due to a reduction in pore size in the cermet cathode, as well as sintering and grain growth of Cu metal in the anode during the reforming. [Copyright &y& Elsevier]

Abstract: Electrochemical decomposition of CO2 and CO gases using a porous cell of Ru-8mol% yttria-stabilized zirconia (YSZ) anode/porous YSZ electrolyte/Ni–YSZ cathode system at 400–800°C was studied by analyzing the flow rate and composition of outlet gas, current density, and phases and elementary distribution of the electrodes and electrolyte. A part of CO2 gas supplied at 50ml/min was decomposed to solid carbon and O2 gas through the cell at the electric field strengths of 0.9–1.0V/cm. The outlet gas at a flow rate of 3ml/min included 61–63% CO2 and 37–39% O2 at 700–800°C and the outlet gas at a flow rate of 50ml/min included 73–96% (average 85%) CO2 and 4–27% (average 15%) O2 at 800°C. On the other hand, the supplied CO gas was also decomposed to solid carbon, O2 and CO2 gases at 800°C. The fraction of outlet gas at a flow rate of 50ml/min during the CO decomposition at 800°C for 5h was 11–36% CO, 59–81% O2 and 2–9% CO2. The detailed decomposition mechanisms of CO2 and CO gases are discussed. Both Ni metal in the cathode and porous YSZ grains under the DC electric field have the ability to decompose CO gas into solid carbon and O2− ions or O2 gas. [Copyright &y& Elsevier]

Abstract: SiC nanopowders of 30nm in diameter were successfully synthesized by laser-pyrolysis with high production rate (1.7kg/h) and high quantity (>2kg). The as-synthesized nanopowders were heat-treated in order to slightly oxidize the surface. It was shown that the heat-treatment does not modify structural properties or morphology but modifies the surface chemistry. Ethanolic suspensions with polyethylenimine (PEI) as dispersant were prepared from the heat-treated powders. The suspensions properties were characterized in terms of rheology, zeta potential and size distribution before and after operational pH adjustment with hydrochloric acid (HCl 1M) or acetic acid (CH3COOH). High concentrated suspensions (28wt%) with low viscosity were obtained after pH adjustment with CH3COOH. Electrophoretic infiltrations of carbon preforms carried out with these suspensions lead to a high quality infiltration of the inter-tows area as well as of the intra-tows area, some tows being completely filled with the nanopowders. [Copyright &y& Elsevier]

Abstract: The formation of the internal barrier layer capacitor (IBLC) structure in CaCu3Ti4O12 (CCTO) ceramics was found to be facilitated by the ceramic heat treatment. Electrically insulating grain boundary (GB) and semi-conducting grain interior areas were characterized by impedance spectroscopy to monitor the evolution of the IBLC structure with increasing sintering temperature T S (975–1100°C). The intrinsic bulk and GB permittivity increased by factors of ≈2 and 300, respectively and the bulk resistivity decreased by a factor of ≈103. These trends were accompanied by increased Cu segregation from the CCTO ceramics as detected by scanning electron microscopy and quantitative energy dispersive analysis of X-rays. The chemical changes due to possible Cu-loss in CCTO ceramics with increasing T S are small and beyond the detection limits of X-ray absorption spectroscopy near Cu and Ti K-edges and Raman Spectroscopy. [Copyright &y& Elsevier]

Abstract: Nanometric-sized yttrium doped HfO2 powders were obtained by applying metathesis and combustion reactions. The tailored composition of solid solutions was: Hf1−x Y x O2−δ with concentration “x” ranging from 0 to 0.2. HfCl4 was used as a source of hafnium whereas Y(NO3)3·6H2O was used as a source of yttrium. The obtained powders were annealed at different temperatures in order to induce crystallization of HfO2. The influence of dopant concentration, annealing temperature and annealing time on powder properties was examined. The XRD analysis revealed that the crystal structure of HfO2 depends on the dopant concentration. The samples doped with 20mol% of yttrium and annealed at 1500°C had high-temperature, cubic structure even after cooling to room temperature. The presence of relatively large amount of dopant was beneficial in stabilizing highly desirable cubic phase of HfO2. It was found that the crystallite size lies in the nanometric range (<10nm). [Copyright &y& Elsevier]

Abstract: Mono, di and trivalent ions containing hydroxyapatite of the formula BiNaCa3(PO4)3OH has been synthesized and the compound''s catalytic activity in three component Biginelli condensation was studied. The compound was characterized by powder XRD, FT-IR, SEM and TGA/DTA techniques. The unit cell dimensions of the compound were determined to be a =9.412(2)Å, C =6.92(2)Å and the unit cell volume is 530.9Å3. The substituted hydroxyapatite phase showed enhanced reactivity in the one pot synthesis of 3,4-dihydropyrimidin-2(1H)-one by Biginelli reaction and resulted in an increased yield of the product. [Copyright &y& Elsevier]

Abstract: The dispersion and co-dispersion behavior of ZrB2 and SiC nanopowders in ethanol solution was studied by sedimentation test, particle size measurement and transmission electron microscope (TEM) analysis. The dispersion behavior of ZrB2 and SiC nanopowders in ethanol solution was strongly dependent on the pH values, types and amounts of dispersant. PEI was found to be effective for the dispersion of both ZrB2 and SiC nanopowders in ethanol solution. With the addition of PEI, the isoelectric points of ZrB2 and SiC nanopowders in ethanol solution were at pH 10 and pH 9.5, and shift to pH 13 and pH 12.3, respectively. The stability of ZrB2 suspension increased with the dispersant content increasing until reached 0.7wt% and well-dispersed SiC slurry can be obtained with more than 2.5wt% PEI. The suitable pH value for the dispersion of ZrB2 and SiC nanopowders should be lower than 12 and 10, respectively. The well co-dispersed ZrB2 and SiC nanocomposite powders can be achieved by using 1wt% or more PEI below pH 10. [Copyright &y& Elsevier]

Abstract: In this work, we have investigated the structural and catalytic properties of Co, Cu and Ni spinel ferrites. Nanostructured ferrites with particle diameters varying from 3 to 10nm were obtained by the co-precipitation process. X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and Mössbauer spectroscopy were used for chemical and structural characterization. The catalytic efficiency of the samples was evaluated by the decomposition of hydrogen peroxide and by the oxidation of methylene blue, monitored via UV–vis spectrophotometry. We observed that the presence of cobalt ions is a crucial factor required to achieve a systematic efficiency of the catalyst in the H2O2 decomposition. In contrast, Cu ferrites presented the better performance in methylene blue oxidation, which can be attributed to the different redox properties of Cu and the easier availability of electrons to participate in the oxidation of organic compounds. [Copyright &y& Elsevier]

Abstract: The effects of additions of zircon (5–17wt%) to conventional single firing ceramic glazes is examined. The structural and morphological characteristics of the glazes were determined by Scanning Electron Microscopy, X-ray diffraction, infra-red spectroscopy, as well as 27Al and 29Si magic angle spinning (MAS) NMR. The presence of zircon microcrystals was revealed by X-ray diffraction (XRD) combined with scanning electron microscopy (SEM) and EDAX microanalysis. The chemical durability of the glasses is revealed to be acceptable for certain practical applications. The color characteristics of the glazes obtained were estimated in the HunterLab system (L*C*h*, emission spectra). The outcomes of the study established correlations between composition, structure and some of the physical properties. [Copyright &y& Elsevier]

Abstract: An inorganic cation exchanger was synthesized from waste sandstone cake using the alkali fusion method. We used two starting materials: one was the original cake and the other was leached cake, which was prepared from the original cake by acid-leaching with 1M HCl solution. Each starting material was mixed with NaOH powder (the weight ratio of NaOH/sandstone=1.6) and then heated at 600°C for 1h to make a fused material. This fused material was then added to distilled water and agitated for one day, then heated at 80°C, 120°C, and 160°C for 8h in reaction bombs under autogenous pressure in order to synthesize the cation exchanger. From the original cake, a mixture of zeolite-X and hydroxysodalite was synthesized at 80°C, hydroxysodalite alone was synthesized at 120°C, and a mixture of hydroxysodalite and tobermorite was synthesized at 160°C. From the leached cake, zeolite-X alone was synthesized at 80°C, a mixture of zeolite-X and hydroxysodalite was synthesized at 120°C, and the hydroxysodalite alone was synthesized at 160°C. By increasing the synthesis temperature, the cation exchange capacity (CEC) of the product from both cakes decreased, and at each synthesis temperature the product from the leached cake had a higher CEC than did the original cake. The product with the highest CEC was the zeolite-X alone synthesized from the leached cake at 80°C, which had a CEC of 230cmol/kg. [Copyright &y& Elsevier]

Abstract: The search for optimal materials and the utilization of proper manufacturing techniques to replace conventional electrolytes are our research objectives for the operation of solid oxide fuel cells under intermediate temperatures. Furthermore, understanding the effects of process parameters will be helpful for obtaining suitable materials for applications. In this study, we investigate the O2/Ar flow ratio effect by employing RF reactive sputtering to fabricate 20mol% Gd-doped ceria (20GDC) films on alumina substrates. The morphology of films was aggregated by nano-scale size of grains which gradually reduced in size from lower to higher O2/Ar flow ratios. The microstructure of films was transferred from incomplete oxidized materials to well-crystallized cubic fluorite structures using an increased O2/Ar flow ratio up to 0.30. The oxygen/metal ratio of films was increased gradually and saturated around 2.05 for O2/Ar flow ratios over 0.25 and remained in uniform composition through whole films for each flow ratios. [Copyright &y& Elsevier]

Abstract: The carbonation–calcination looping cycle of calcium-based sorbents is considered as an attractive method for CO2 capture from combustion gases because it can reduce the cost during the capture steps compared to conventional technologies, e.g., solvent scrubbing. In this study, waste eggshell was used as raw material for calcium oxide-based sorbent production. The commercially available calcium carbonate was employed for comparison purpose. Calcination behavior, crystal type and crystallinity, surface chemistry, qualitative and quantitative elemental information, specific surface area and pore size, morphology of the waste eggshell and the calcined waste eggshell were characterized by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), N2 sorption analysis and scanning electron microscopy (SEM), respectively. The carbonation–calcination cycles were carried out using a TGA unit with high purity CO2 (99.999%). It was found that the carbonation conversion of the calcined eggshell was higher than that of the calcined commercially available calcium carbonate after several cycles at the same reaction conditions. This could be due to the fact that the calcined eggshell exhibited smaller particle size and appeared more macropore volume than the calcined commercially available calcium carbonate. As results, the calcined eggshell provided a higher exposed surface for the surface reaction of CO2. [Copyright &y& Elsevier]

Abstract: The purpose of this work was to produce and characterize SiO2–CaO–P2O5 bioactive glass nanoparticles with negative zeta potential for possible use in biomedical applications. 63S bioactive glass was obtained using the sol–gel method. X-ray fluorescence (XRF) spectroscopy and dispersive X-ray analysis (EDX) confirmed the preparation of the 63S bioactive glass with 62.17% SiO2, 28.47% CaO and 9.25% P2O5 (in molar percentage). The in vitro apatite forming ability of prepared bioactive glass was evaluated by Fourier transform infrared spectroscopy (FTIR) after immersion in simulated body fluid (SBF). The result showed that high crystalline hydroxyapatite can form on glass particles. By the gas adsorption (BET method), particle specific surface area and theoretical particle size were 223.6±0.5m2/g and ∼24nm, respectively. Laser dynamic light scattering (DLS) indicated particles were mostly agglomerated and had an average diameter between 100 and 500nm. Finally, using laser Doppler electrophoresis (LDE) the zeta potential of bioactive glass nanoparticles suspended in physiological saline was determined. The zeta potential was negative for acidic, neutral and basic pH values and was −16.18±1.8mV at pH 7.4. In summary, the sol–gel derived nanoparticles revealed in vitro bioactivity in SBF and had a negative zeta potential in physiological saline solution. This negative surface charge is due to the amount and kind of the ions in glass structure and according to the literature, promotes cell attachment and facilitates osteogenesis. The nanometric particle size, bioactivity and negative zeta potential make this material a possible candidate for bone tissue engineering. [Copyright &y& Elsevier]