Effects of BaCu（B2O5 ） addition on sintering temperature and microwave dielectric properties of Ba5Nb4O15–BaWO4 ceramics

The effects of BaCu(B2O5)(BCB) addition on the microstructure, phase formation, and microwave dielectric properties of Ba5Nb4O15–BaWO4ceramic are investigated. As a sintering aid, BaCu(B2O5) ceramic could effectively lower the sintering temperature of Ba5Nb4O15–BaWO4ceramic from 1100?C to 950?C due to the liquid-phase effect. Meanwhile,BaCu(B2O5) addition effectively improves the densification of Ba5Nb4O15–BaWO4ceramic and significantly influences the microwave dielectric properties. X-ray diffraction analysis reveals that Ba5Nb4O15and BaWO4coexist with no crystal phase of BaCu(B2O5) in the sintered ceramics. The Ba5Nb4O15–BaWO4ceramics with 1.0 wt% BaCu(B2O5) sintered at 950?C for 2 h presents good microwave dielectric properties of εr = 19.0, high Q × f of 33802 GHz and low τfof2.5 ppm/?C.     

乙炔电催化氧化制备草酸的机理研究

选择铂为电极电催化乙炔合成草酸,通过紫外-可见分光光度法和红外光谱法对产品进行表征,利用第一性原理计算方法探讨乙炔在催化剂Pt(111)表面的吸附情况,采用循环伏安法（CV）研究铂电极在硫酸钠溶液中氧化乙炔的电极过程,重点测定电极的稳态极化曲线并根据极化曲线推算塔菲尔斜率,结合表观传递系数及反应级数对拟定的乙炔电催化氧化制备草酸的反应机理进行验证. 实验结果表明,乙炔分子在Pt(111)面上呈平行桥键构型时吸附最稳定;铂电极在含体积分数为2%丙酮的0.4 mol·L^-1硫酸钠溶液中可将乙炔电催化氧化为草酸;反应的速率控制步骤为.     

Effects of BaCu（B2Os） addition on sintering temperature and microwave dielectric properties of BasNb4O15-BaWO4 ceramics

The effects of BaCu（B2Os） （BCB） addition on the microstructure, phase formation, and microwave dielectric proper- ties of BasNb4015-BaWO4 ceramic are investigated. As a sintering aid, BaCu（B2Os） ceramic could effectively lower the sintering temperature of BasNb4015-BaWO4 ceramic from 1100 ℃ to 950 ℃ due to the liquid-phase effect. Meanwhile, BaCu（B2Os） addition effectively improves the densification of BasNb4015-BaWO4 ceramic and significantly influences the microwave dielectric properties. X-ray diffraction analysis reveals that BasNb4015 and BaWO4 coexist with no crystal phase of BaCu（B2Os） in the sintered ceramics. The BasNb4015-BaWO4 ceramics with 1.0 wt% BaCu（B2Os） sintered at 950 ℃ for 2 h presents good microwave dielectric properties of er = 19.0, high Q× f of 33802 GHz and low vf of 2.5 ppm/℃.     

丙烯醇反马氏水合制备1,3-丙二醇

1,3-丙二醇具有很高的经济价值，是合成纤维聚对苯二甲酸丙二酯的重要原料。基于甘油甲酸介入法获得的丙烯醇作为平台分子，通过丙烯醇与TiCl4-NaBH4反应，首次实现常温常压下1,3-丙二醇的制备, 为1,3-丙二醇的合成提供了一条新的路径。在最优条件下，1,3-丙二醇的产率68.73%，推测反应机理为：TiCl4和NaBH4发生反应，生成中间体 “BH3”，进而实现了丙烯醇反马氏水合制备1,3-丙二醇。