Nd0.7Sr0.3MnO3中显微结构相关电致电阻效应

Microstructure dependence of the electroresistance of Nd_(0.7)Sr_(0.3)MnO_3

用固相反应和高能球磨合成后续热处理两种方法分别得到钙钛矿结构Nd0.7Sr0.3MnO3氧化物.两种不同方法得到的多晶样品,虽然晶体结构相同,化学成分和晶粒大小相近,但它们电输运性质却表现出很大差异.用固相反应法制得的样品的电阻几乎不随负载电流的变化而变化,即不表现电致电阻行为;而通过高能球磨合成后续热处理方法得到的样品电阻随外加电流增大而急剧减小,出现显著电致电阻效应.产生这种截然不同电输运特性的原因可能与样品的显微结构和界面性质有关.

Nd0.7Sr0.3MnO3 ceramics of perovskite-type were respectively prepared by solid-state reaction and high-energy ball milling with post heating-treatment. The samples obtained using these methods show a great of difference in electrical transport despite having the same crystallographic structure, similar grain size and chemical composition. For the sample prepared by solid-state reaction, the electrical resistance keeps unchanged with current loads and no electroresistance effect takes place. However, for the sample prepared by high-energy ball milling with post heating treatment, the electrical resistance decreases remarkably with increasing current loads and shows colossal electroresistance effect. The microstructure of materials, in particular the screw dislocation-like structure, is supposed to be responsible for the difference in electrical transport.