Microstructure dependence of the electroresistance of Nd0.7Sr0.3MnO3

Nd0.7Sr0.3 MnO3 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.