Advanced Materials Research Vol. 624

Abstract: Bi_3.25Gd_0.75Ti_2.97V_0.03O₁₂ (BGTV) ceramics were prepared by solid state reaction. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed plate-like grains with random orientation. The remanent polarization and the coercive field of the BGTV were 24μC/cm² and 65kV/cm at an electric field of 100kV/cm, respectively. These ferroelectric properties of BGTV are superior to V-doped Bi₄Ti₃O₁₂ (~20μC/cm² and 80kV/cm) and (Sr, Ta)-doped Bi₄Ti₃O₁₂ (~12μC/cm² and 71kV/cm) ceramics. In addition, the dense ceramics of BGTV could be obtained by sintering at temperatures 100─200°C lower than those of the SrBi₂Ta₂O₉ system.

Abstract: The ferroelectricity of Bi_3.25Nd_0.75Ti₃O₁₂ (BNT), and Bi_3.25Nd_0.75Ti_2.97V_0.03O₁₂ (BNTV) ceramics prepared at 1100°C by a conventional ceramic technique was investigated. These ceramics possess random-oriented polycrystalline structure. The remanent polarization (Pr) and coercive field (Ec) of the BNT ceramics are 16 µC/cm² and 65kV/cm, respectively. Furthermore, V substitution improves the Pr value of the BNTV ceramics up to 23 μC/cm², which is much larger than that of the BNT ceramics. Therefore, co-sustitution of Nd and V in Bi₄Ti₃O₁₂ ceramic is effective for the improvement of its ferroelectricity.

Abstract: Bi_3.25Er_0.75Ti₃O₁₂(BET) and Bi_3.25Er_0.75Ti_2.97V_0.03O₁₂(BETV) thin films with random orientation were fabricated on Pt/Ti/SiO₂/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. The experimental results indicated that Er doping into Bi₄Ti₃O₁₂ (BIT) also result in a remarkable improvement in ferroelectric property. The remanent polarization (Pr) and coercive field (Ec) of the BET film were 17 μC/cm² and 80 kV/cm, respectively. Furthermore, V substitution improves the Er value of the BETV films up to 28 μC/cm², which is much larger than that of the BET film.

Abstract: The electrical properties of Gd₂O₃-bismuth titanate (Bi_4-xGd_xTi₃O₁₂) prepared by a conventional ceramic technique have been investigated. At applied d.c. field below 200V/mm, the current-voltage curve of Gd-doped sample exhibits a simple ohmic behavior. The impedance spectrum of Gd-doped sample indicates that consist of semiconducting grain and moderately insulating grain boundary regions. XRD, SEM and EPMA analyses reveal crystalline phase characterized by a Bi-layered perovskite structure of Bi₄Ti₃O₁₂ and the distribution of every element is uniform. Gd-doped sample exhibit randomly oriented and plate-like morphology.

Abstract: YSZ/NiO composite powders were successfully synthesized by chemical liquid phase co-precipitation process. YSZ/NiO composite ceramic bodies were prepared by gel casting. Three different types and amounts of pore-formers were added into the YSZ/NiO suspension. The results show that the YSZ/NiO composite with the best properties and optimal porosity of 42.18% was obtained when the 7wt.% corn meal was used as pore-former.

Abstract: Doping perovskite structure ceramics constitute an important type of solid oxides fuel cell (SOFC) cathode materials. In this study, BaCe1-xTaxO3+δ powders were prepared by solid state reaction at 1500oC for 4h. BaCe1-xTaxO3+δ ceramics were pressureless sintered at 1600oC for 5h. The results indicated that the relative density of BaCe1-xTaxO3+δ ceramics reached the range of 84.15 - 90.88%. At the frequency of 1Hz, the conductivity of BaCe0.65Ta0.35O3+δ ceramic samples varied greatly, when the testing temperature rose from room temperature to 900oC in increments of 100oC. The highest conductivity was obtained at 600oC with the value of 6.74×10-5 S/cm.

Abstract: TiO2 photocatalysts doped with different metal ions were prepared by adsorption phase synthesis. The influence of different dopant metal ions with various concentrations on the crystallization of TiO2 was ex-plored by XRD. Then photodegradation experiments of methyl-orange were employed to evaluate the activity of these photocatalysts. The results indicated that the crystallization of TiO2 was restricted after doping, due to replacement of Ti4+ in TiO2 lattice structure by other metal ions. And the restriction became stronger with radius and concentration of doping ions increasing. There was an optimum dopant concentration appeared during preparation of TiO2 doped with Cd2+ and Fe3+. When dopant concentration was less or more than this optimum value, the photocatalytic activity of TiO2 doped with metal ions was lower than that of TiO2 without doping. Since radius of Fe3+ was close to Ti4+, the influence of Fe3+ dopant concentration on crystallization and activity of TiO2 was more obvious than that of Cd2+ doping.

Abstract: Fabrication of lithium silicate powder containing lithium titanate by solid phase reaction method. LiFabrication of lithium silicate powder doped with lithium titanate by solid-state reaction. Take lithium carbonate, silicon dioxide and titania as raw materials and then these powders were mixed according to the different ratios and grinded in an agate mortar for 15 min. And then the mixture were dried at 80°C. Finally, the samples were sintered in vacuum tube furnace at 750, 800, 850 and 900°C for 2h. Thermogravimetric analysis, differential scanning calorimetry and XRD analysis were carried out systematically in this paper. The reaction process and mechanism at different temperatures and the effect of the different ratios and sintering temperature were discussed. Experimental results showed that lithium titanate component increased with increasing amount of titanium dioxide. While the mixture were sintered at 900°C for 2h, there would have lithium silicate and lithium titanate phase.

Abstract: Mg²⁺2+,Al₃₊ Co-doped Li₃V₂(PO₄)₃/C powder was synthesized by sol-gel method under nitrogen. The crystal structure and micrograph ofLi₃V₂(PO₄)₃/C powder before and after doping was investigated by XRD, SEM and FT-IR. The effect of Mg2+/Al3+ Co-doping onLi₃V₂(PO₄)₃/C powder was discussed. The results indicated that Mg²⁺2+,Al₃₊ Co-doping did not change the crystal structure of Li₃V₂(PO₄)₃, but decreased the grain size of the as-synthesized powder. The FT-IR analysis indicated that weak Al-O bond was generated after doping.

Abstract: Abstract: The lithium orthosilicate pebbles was fabricated by melt spraying method with lithium carbonate (Li2CO3) and silicon dioxide (SiO2). By alter heat treatment temperature to study different particle sizes of lithium orthosilicate pebbles of strength and phase. Lithium orthosilicate pebbles which were heat treated by vacuum tube type furnace study change of phase ,by XRD to study the change of phase after the heat treatment and tested strength by universal testing machine. Heat treatment would alter strength and phase by vacuum tube type furnace.