Ba₃Al₂O₆ was successfully synthesized by using solid-state reaction between BaCO₃ and Al₂O₃ powers. The phase structure and morphologies of product were characterized by X-ray diffraction and scanning electron microscopy, respectively. The reversible reaction between Ba₃Al₂O₆ and CO₂ has been expressed as 1/2Ba₃Al₂O₆ + CO₂ = 1/2BaAl₂O₄ + BaCO₃, and the corresponding thermodynamic calculations were also carried out in the present study. Ba₃Al₂O₆ was found to capture CO₂ over a wide temperature range with a maximum weight increase of 15.68%. The kinetics of absorption and desorption reactions between Ba₃Al₂O₆ and CO₂ were investigated by thermogravimetry, at various temperatures under different partial pressures of CO₂. Based on the kinetic analyses, the absorption process of CO₂ is controlled by the diffusion in the inner solid product layer, and its kinetics can be described by the widely used Ginstling-Brounshtein function, with the activation energies extracted to be 14.11, 13.85 and 12.89 kJ/mol when the concentration of CO₂ are 10, 50 and 100% CO₂, respectively.

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The microstructure of (Mg_0.95Ni_0.05)₄(Nb_1−xTa_x)₂O₉ ceramics was analyzed using X-ray diffractometry and scanning electron microscopy. The quality factor (Q×f) values of (Mg_0.95Ni_0.05)₄(Nb_1−xTa_x)₂O₉ (x = 1) ceramics increase with increasing sintering temperature, with the maximum value obtained at 1375°C. The maximum values of electric permittivity (ε) and Q×f were 12.76 and 442,000 GHz, respectively, for (Mg_0.95Ni_0.05)₄(Nb_1−xTa_x)₂O₉ (x = 1) ceramics sintered at 1375°C for 4 h. Furthermore, the temperature coefficient of resonant frequency (τ_f) measured for (Mg_0.95Ni_0.05)₄(Nb_1−xTa_x)₂O₉ (x = 1) ceramics is −54 ppm/°C.

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LiFePO₄ is a promising cathode material for lithium-ion batteries which has attracted much attention because of its high energy density, low cost and superior safety. LiFePO₄ is synthesized using the citrate process in the oxygen and nitrogen atmospheres, and the crystal structure is analyzed by X-ray diffraction. The LiFePO₄ synthesized in the nitrogen atmosphere shows the single phase of Olivine structure but the second phase of Fe₂O₃ in the oxygen atmosphere. The microstructure observation indicates that the porous flower-like particles appears in the nitrogen and oxygen atmospheres but more clear structure of LiFePO₄ synthesized in nitrogen atmosphere. This study also compares the synthesis result of LiFePO₄ depending on the existence of the Chelate process after nitrogen fixation of synthesis process. The LiFePO₄ with the addition of Chelate process shows the single phase but spherical particles are observed. The electrochemical characteristics of LiFePO₄ are evaluated using the coin cells. The LiFePO₄ with no additional chelate process shows the maximum discharge capacity of 160 mAh/g at 0.2C and 155 mAh/g at 1C. The capacity shows no reduction after the cycle test of 45 times with the current rate of 1C. Meanwhile, after chelate process, the LiFePO₄ shows 150 mAh/g at 0.2C and 108 mAh/g at 1C, which indicates substantial difference. After 5 cycles, its capacity has reduced more than 40 mAh/g.

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The reversible change of diffraction efficiency is confirmed in the sol–gel-derived Cl-containing inorganic–organic hybrid films co-doped with Ag and Cu by interfered blue and green laser irradiations. The change of diffraction efficiency is due to absorbance change, which is caused by a mutual conversion of Ag and AgCl nanoparticles upon the laser irradiations. The role of Cu is clarified that electrons are transferred between Ag and Cu, which is indispensable for the reversibility of the absorbance change. The Ag nanoparticles are observed to be aggregated after several cycles of blue and green laser irradiations. The aggregation would occur because of the migration of Ag element during laser irradiation. The diffraction efficiency of the film reaches 0.75% after interfered blue laser irradiation; then it decreases almost 0% by green laser irradiation. Subsequent interfered blue laser irradiation increases again the diffraction efficiency up to 0.59%. This suggests that our materials can be used as rewritable hologram recording media.

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Cerium oxide is commonly used as a catalyst for the oxidation of carbon monoxide (CO) in vehicle exhaust gases, and it is used as a petroleum-cracking catalyst in oil refineries. In this study, cerium aluminosilicophosphate glasses were synthesized and various physical and catalytic properties were measured, including optical properties and decomposition temperatures, by thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) analysis. Ce³⁺/Ce⁴⁺ ratios and structural changes in the glass attributable to doping with ∼25 mol % CeO₂ were investigated by FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. Changes in the catalytic properties of the glasses as a function of CeO₂ content were confirmed by changes in the decomposition starting temperatures. These temperatures decreased with increasing CeO₂ content of the glasses. We also discuss the role of CeO₂ in terms of the catalytic properties of the glass structure.

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The effects of the new additives system BaO–B₂O₃–SiO₂ on the corundum abrasive synthesized by sol–gel process were investigated. The thermal behavior of the xerogel was examined by thermogravimetry-differential scanning calorimetry (TG-DSC) and X-ray diffractometer (XRD). The results showed that the phase transformation temperature from γ- to α-Al₂O₃ was reduced. With the addition of BaO, B₂O₃ and SiO₂ fixed at 1.5 wt % of the total weight of corundum abrasive and in the molar ratio of 8:12:80, the samples sintered at 1400°C for 0.5 h reached about 99.4% of theoretical density. The single particle compressive strength was higher than 45 N with a homogeneous microstructure. The influence of each additive and their synergetic interactions on the sintering of abrasives were also discussed in detail.

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In this study, laminated composites consisting of ZrB₂–SiC (ZS) ceramic and carbon fiber (Cf) reinforced-ZrB₂–SiC matrix composites (Cf/ZrB₂–SiC, hereafter denoted by CfZS) were fabricated by hot-pressing. The effects of the layer thickness ratio of ZS to CfZS (ZS/CfZS) and the fiber concentration on the flexural strength were investigated. The flexural strength of the laminated composites was improved compared to that of the single-composites and the improvement was enhanced with increase of the ZS/CfZS ratio. However, the flexural strength decreased with increasing the fiber concentration of CfZS. In addition, the crack propagation behavior of the laminated composites was examined under indent cracking. The results showed that the crack propagation behavior related to the fiber concentration of CfZS, irrespective of the layer thickness. The cracks induced by the indenter rapidly propagated through the CfZS layer when the fiber volume fraction was 10%. However, the cracks were arrested ahead the CfZS layers for the fiber volume fraction equal to or greater than 30%.

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The structures of a SiO₂ layers synthesized using perhydropolysilazane [PHPS, labeled as SiO₂(PHPS)] on both Si and Fe/Si substrates were studied using Fourier transform infrared spectroscopy (FT-IR) and neutron reflectivity (NR) analysis. The FT-IR results revealed that no unreacted PHPS remained and that the primary component of the SiO₂(PHPS) layer could be considered to be SiO₂. The NR analysis suggested that a uniform SiO₂(PHPS) layer was synthesized on the Si and Fe/Si substrate and that the density of this SiO₂(PHPS)layer was lower than that of natural SiO₂. In addition, the density of the SiO₂(PHPS) layer was altered by varying both the thickness and the type of substrate used. These results indicated that the variation in the density of the SiO₂(PHPS) layer depended on the efficiency of cross-linking reaction between the silazane oligomers in the PHPS coating.

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Oxides of xZnO–(100 − x)GeO₂ (x = 0, 25, 50, 66.7, 75 and 100 mol %) were produced mainly by sol–gel method. Their XRD patterns show that there exist hexagonal ZnO (wurtzite), rhombohedral Zn₂GeO₄, and hexagonal GeO₂ (α-quartz type). All the oxides showed second harmonic generation (SHG) green emission peaking around 532 nm with luminance of about 0.05–1.20 cd·m⁻² when irradiated with an Nd:YAG pulsed laser of 1064 nm. The more the amount of hexagonal ZnO or hexagonal GeO₂ increased, the more the SHG emission intensity increased. Both of hexagonal ZnO and hexagonal GeO₂ do not have centrosymmetry and cause SHG, while rhombohedral Zn₂GeO₄ has centrosymmetry and does not. Therefore, the SHG emission intensity was changed with the amounts of these ZnO and GeO₂ crystals.

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Fibers of Poly(3-hydroxybutylate-co-4-hydroxybutylate) [P(3HB-co-4HB)], poly(L-lactic acid) (PLLA) or poly(lactic-co-glycolic acid) (PLGA) have been prepared by a polymer solution casting method. These have been incorporated (up to 3% volume) into calcium phosphate cement (CPC) to improve the mechanical properties. Semi-quantitative X-ray analysis showed that the incorporation of the fibers does not affect the formation of hydroxyapatite from the initial starting materials. Three-point bending tests showed that all polymer fibers influenced the flexural strength and elastic modulus of the fiber-reinforced CPC. P(3HB-co-4HB) and PLGA fiber reinforced CPCs displayed flexural strengths of more than 1 MPa, even after a 3-mm displacement. P(3HB-co-4HB) fiber-reinforced CPC exhibited the most bridging fibers across a crack formed by the mechanical tests. The bulk shape of the CPC reinforced with P(3HB-co-4HB) fibers was maintained at 25% of the stain in the compressive test, despite of formation of cracks.

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