Advanced Ceramics Progress
Volume:3 Issue: 3, Summer 2017

Lead free, eco-friendly bismuth borate glasses doped with alkali oxides of composition xLi2O(30-x)Na2O瘻羵똻 (x = 5,10,15,20,25) were prepared by melt quenching technique. Amorphous nature of glasses was confirmed by X-ray diffraction. Density measurements were carried out at room temperature by standard principle of Archimedes with Xylene as an immersion liquid. The non-linear behavior of density, molar volume, glass transition temperature, direct and indirect optical band gaps confirm the mixed alkali effect. The FTIR analysis revealed that the network structure consists of BO3, BO4 units and BiO6 octahedral units. UV-vis spectroscopy shows no sharp absorption edges giving a clear indication of the amorphous nature of the glasses.

In the present investigation, γ-alumina nanoparticles with particle sizes less than 10 nm, high specific surface area (351 m2/g), high pore volumes and relatively narrow pore sizes distribution was prepared via sol-gel method in presence of aluminum isopropoxide as an aluminum precursor, distilled water, acetic acid as hydrolysis rate controller and tert-butanol as solvent. They had meso and macro porosities which the most of pores are in cylindrical shape. The received powder was characterized by simultaneous thermal analysis (STA) method. The calcined γ-alumina nanoparticles were characterized using X-ray diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and nitrogen adsorption-desorption techniques. This study revealed that the precursor and solvent types, weight ratios of reactants, calcination temperatures and times were important factors to preparation of γ-alumina with high surface area and well defined narrow pore size distribution for heavy metals adsorption.

In this paper, the morphology of chemically etched silicon with various concentration is reported. The surface of Silicon (100) has pyramidal structures which can be used for anti-reflection applications in solar cells. Pyramidal structures can capture incident sun light therefore can enhance the efficiency of silicon solar cells. The structure of silicon pyramid was studied using scanning electron microscopy (SEM) while the optical properties was investigated by reflectance spectrometer.

Lithium-iron-orthosilicate is one of the most promising cathode materials for Li-ion batteries due to its safety, environmental brightness and potentially low cost. In order to produce a low cost cathode material, Li2FeSiO4/C samples are synthesized via sol-gel (SG; one sample) and solid state (SS; two samples with different carbon content), starting from Fe (III) in the raw materials (low pristine materials). The three samples are characterized for purity, structure, and morphology. The electrochemical tests showed the different charge-discharge behaviours of the SS and SG samples. Electrochemical behaviours were investigated in terms of voltage vs. square root of capacity diagrams and their slopes. The best results are obtained with the SS sample containing the larger amount of carbon.

Nanoporous glass-ceramics were prepared with composition 45CaO-25TiO2-35P2O5 (mol%). Two molar percent of Na2O was added as a flux to the composition. With the aforementioned composition, glass melted and crystallized into glass-ceramics containing β-Ca3(PO4)2 and CaTi4(PO4)6 as the main phases. The differential thermal analysis (DTA) was conducted to determine the suitable temperatures for nucleation and crystallization. Various times were examined for nucleation and the best nucleation time was chosen. The microstructure of final nucleated sample was observed by Scanning Electron Microscopy (SEM). Then, the glasses were crystallized and identified by X-ray Diffraction (XRD).The microstructures of crystallized specimens were studied by SEM.The glass-ceramics were leached in HCl, resulting β-Ca3(PO4)2 was dissolved out leaving a porous structure as CaTi4(PO4)6. It was found that specific surface area and average pore size diameter of the nanoporous glass-ceramics were controlled by the correct choice of heat treatment parameters. Using the optimal conditions for the production of nanoporous glass-ceramics with minimum pore size, 26 m2 and 12.3 were obtained for the specific surface area and pore diameter, respectively.

In this study, small fraction of NiTi (5 wt%) was added to Yttria stabilized zirconia (YSZ) top coat to improve it sliding wear resistance. The measurement of width of wear tracks after wear tests under a 15 N load for 100 m sliding distances showed that the width of wear track in NiTi-YSZ coating is shorter than that in YSZ coating which depicts the higher wear resistance of NiTi-YSZ coating samples. It is believed that the higher H/E value and pseudoelasticity effect of NiTi are two important factors which improved the wear performance of applied coatings. Also, to evaluate the role of addition of a NiTi (5 wt%)–YSZ buffer layer on the durability of YSZ coatings during wear operation, wear tests with a 20 N normal load and with a constant frequency were conducted on coated samples. It was observed that the conventional YSZ coating cracked and delaminated after about 60 m sliding distance. However, in samples which contain a NiTi (5 wt%) –YSZ buffer layer delamination was not observed until 100 m sliding distance which is attributed to the ability of NiTi for accommodation of interface stresses and hindering of premature delamination during wear test under higher loads.

In this study, TiO2 nanoparticles have been synthesized by sol-gel method. Then, the effects of the different pHs, stirring times, surfactants (CTAB and Span 20) and temperatures on TiO2 nanoparticles were studied. The X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) analyses were used to characterize the samples. The observations revealed that, the pH of 3.5 and 36 h stirring time could provide dispersion without agglomeration in nanoparticle powder with rutile and anatase phases. However, at higher pH, the powder resulted in the formation of anatase phase. Implementing CTAB as a surfactant modified the shape, size, and distribution of TiO2 nanoparticles better than the Span 20 as a surfactant. Finally, the nanopowder was calcined at 450, 550 and 650 °C. It obviously showed thatby increasing the temperature, the size of nanoparticles increased which might be due to accelerate the crystal growth of titanium dioxide at high calcination temperature.