Characterization of A-site excessive perovskite La0.7-xSmx＋0.02Ca0.3CrO3-δ

La0.7-xSmx+0.02Ca0.3CrO3-δ(0≤x≤0.4) powders with A-site excessive perovskite structure were synthesized by auto-ignition process and characterized. X-ray diffraction (XRD) patterns of samples after sintering at 1400℃ for 4 h were indexed as tetragonal structure. The relative densities were all above 96% although decreased slightly with the increasing content of samarium, indicating that the excessive A-site element was helpful to enhance their sinterability. Conductivities of the specimens in air increased with increasing content of samar-ium. The conductivity of La0.6Sm0.12Ca0.3CrO3-δ was 33.6 S/cm in air at 700 ℃ which was about 1.7 times as high as that of La0.7Ca0.3CrO3-δ (20.1 S/cm). Average thermal expansion coefficients (TECS) of the specimens increased from 11.06×10-6 to 12.72×10-6 K-1 when x in-creased from 0 to 0.4, and they were close to that of Y doped ZrO2 (YSZ). La0.7-xSmx+0.02Ca0.3CrO<3-δ>(0.1≤x≤0.3) were good choices for in-termediate temperature solid oxide fuel cells (IT-SOFCs) interconnect materials.     

气-液-固反应合成超细碳酸钙的研究

对气-液-固三相系统制备碳酸钙进行了探讨,优化了碳化反应参数,研究了石灰石的预处 理技术,在降低氢氧化钙质量分数、提高二氧化碳体积分数和搅拌速度的条件下获得最小粒度的碳酸 钙,并合成了立方形、球形、针形三种形状的碳酸钙。     

利用电石渣制备针叶形碳酸钙的研究

为有效利用电石渣资源，以电石渣为原料合成了针叶形碳酸钙。利用XRD、SEM等研究了电石渣的预处理方式、溶液的pH值对碳酸钙纯度和白度的影响，以及碳化反应温度、添加剂对针叶形碳酸钙形成的影响。结果表明：电石渣在105℃下干燥2h的方式进行预处理，且控制碳化反应溶液的pH＞7时，可获得纯度＞97％、白度＞98的针叶形碳酸钙。碳化反应温度是影响针叶形碳酸钙形成的主要因素，合成针叶形碳酸钙的最佳碳化反应温度为80℃左右，其含量可达94％左右。添加剂MgCl2对针叶形碳酸钙晶体的长径比也有较大影响。利用工业副产物电石渣可以合成高纯度针叶形碳酸钙。     

静电纺丝技术在固体氧化物燃料电池电极材料的应用

近些年，纳米纤维被用于燃料电池材料时具有优异的性能，引起了人们的广泛关注。静电纺丝技术是一种低成本，高效可控，操作简单的纤维制备方法。电极材料的微观形貌对于电池性能具有显著影响。将静电纺丝技术的影响因素归纳为内部参数、工艺参数和环境参数三类，分别讨论其对材料微观形貌的影响。同时对于静电纺丝所形成电池纤维结构进行了相关归纳，并对比了不同微观结构所获得的性能。此外，总结归纳了静电纺丝应用于固体氧化物燃料电池材料的最新研究进展，特别强调了复合电极材料的发展现状，以及其微观形成机理，为相关研究者提供研究思路。