高岭石的掺杂对Li_(0.3)La_(2/3)Ti_(0.7)P_(0.3)O_(3.3)体系性能的影响

Effect of dopping kaolinite on properties of Li_(0.3)La_(2/3)Ti_(0.7)P_(0.3)O_(3.3) system

采用高温固相反应的方法合成了Li0.3La2/3Ti0.7P0.3O3.3系统锂快离子导体。交流阻抗测量表明，随着高岭石掺杂量的增加体系的室温离子电导率从9．0×10^-5S／cm下降到9．73×10^-6S／cm。利用电导率与温度的关系计算出其从25～400℃温区里的平均活化能约为20kJ／mol。X射线粉末衍射显示高岭石掺杂对复合体系的结构没什么影响，体系仍然具有钙钛矿型结构。主要相态为Li3xLa2/3-xTiO3钙钛矿固溶体和LaPO4，由于高岭石中所含的杂质，随着高岭石掺杂量的增加（x〉0．04）而出现未知的杂相；红外测试表明Si^4＋、Al^3＋的引入使得PO4^3-的畸变得到抑制。

Li0.3La2/3Ti0.7P0.3O3.3 fast ionic conductor was synthesized by high temperature solid state reaction. A.C. impedance measurements show that the compositions of system have better eonduetivities in low doping content of kaolinite, but the conductivity goes down from 9.0×10^-5S/cm to 9.73×10^-6S/cm with increasing the content of kaolinite. The activation energy is about 20kJ/mol in the temperature range of 25 400℃. X-ray powder diffraction shows that the doping kaolinite would not affect the structure of compositions in the system. The main phase is Li3xLa2/3-xTiO3 perovskite solid solution, LaPO4 as a second phase also can be found. With increasing the content of kaolinite （x〉0. 04）, an unsure phase appears. IR measurement indicates that the structure disorder of PO4^3- in the system would be suppressed by kaolinite doping.