Fe离子掺杂对La_(0.67)Ca_(0.33)Mn_(1-x)Fe_xO_3体系晶体结构、输运性质的影响

采用固相反应法制备了La0.67Ca0.33Mn1-xFexO3(0 x 0.2)系列样品.实验研究了Fe离子掺杂稀土锰氧化物La0.67Ca0.33MnO3的电输运性质、微观结构和导电机制.结果表明:样品高温下导电遵从Mott变程跳跃机制;相同温度下烧结的样品,体系电阻率急剧增加,绝缘—金属转变温度TIM向低温方向移动.相同Fe替代含量的样品,在1200℃、1250℃、1300℃3个不同烧结温度下,晶格常数c变化不大,晶格常数a、b和晶胞体积随着烧结温度的升高而减小,晶体颗粒和体系电阻率随着烧结温度的升高而增大,绝缘—金属转变温度TIM向高温方向移动.

Effect if Fe Substitution on the Crystal Structure and Transport Properties of Layered Perovskite Manganite La0.67Ca0.33Mn1-xFexO3

La0.67Ca0.33Mn1-xFexO3 has been prepared by solid reaction method.The influences of doping Fe on the crystal structure and transport properties of the layered perovskite manganite La0.67Ca0.33Mn1-xFexO3 are investigated.The result indicates that the temperature dependence of resistance follows the formula above the metal-insulator transition temperatures.In the same sinter temperature with increasing of Fe content the crystal lattice and the crystal vol.changes little,while the resistance increases rapidly and the metal-insulator transition tenperature moves to lower temperature.The crystal lattice c of the same Fe content samples prepared by increasing sinter temperature(1 200 ℃、1 250 ℃、1 300 ℃) has no change but the crystal lattice a,b and its vol.decreases,the crystal grain size and resistance increase and the metal-insulator transition temperature moves to higher temperature.