La0.7Ca0.3MnO3和CeO2混合块状样品电输运性质及使用分形迭代电阻网络模型的计算模拟

固相反应方法制得的La_0.7Ca_0.3MnO₃ (LCMO)粉末与Ce O₂粉末均匀混合后压块烧结,对其进行了电阻率随温度变化的测量.观察到样品电阻率存在绝缘体-金属转变. 研究了烧结工艺、CeO₂的混合比例与样品的电阻率、结构和表面形貌的关系.结 果表明， 制备工艺对材料性能有相当大的影响，其中较低温度的烧结主要影响小晶粒及其晶粒间界， 而高温长时间烧结将影响大晶粒的形成.利用三维随机电阻网络（RRN）模型和蒙特卡罗方法 对这种混合块状样品的输运性质进行了模拟，模拟中使用了一种新的RRN平均方法.该模型得 到的数值模拟结果与实验结果在定性上是一致的.这说明以RRN模型来理解LCMO(x)-CeO ₂(1-x) 复合体系的导电状况是合理的，提出的随机电阻网络平均方法是合适的 .关键词：0.7Ca_0.3MnO₃')" href="#">La_0.7Ca_0.3MnO₃绝缘体-金属转变随 机电阻网络蒙特卡罗模拟

Electronic transport properties and simulation of random resistor network in granular mixture system of La0.7Ca0.3MnO3 and CeO 2

Granular mixture samples were prepared with La_ 0.7Ca_ 0.3MnO_3(synthesized by solid reaction) and CeO_2 mixed, pressed and sintered under different conditions. In resistivity versus temperature R(T) measurements, a metal-insulator transition was observed. R(T) data demonstrated that the sintering condition had a strong influence on the properties of the samples. A low sintering temperature had influence on the growth of small granules and their boundaries,a high-temperature and long-time sintering resulted in the formation of large granules. A random resistor network (RRN) model with a new iterative average method was used to simulate the transport property of the mixture samples. The simulation and experimental result in agreement. The result indicates that the RRN model is reasonable for understanding the electronic transport of the granular mixture samples consisting of La_ 0.7Ca_ 0.3MnO_3 and CeO_2.