Mechanochemical effects on microstructure and transport properties of nanocrystalline La0.8Na0.2MnO3 ceramics

Mechanochemical effects on microstructure and transport properties of the sol–gel prepared nanocrystalline La0.8Na0.2MnO3 ceramics have been studied. It was found that with the prolonging of the milling time the crystalline size as well as the particle size obviously decreased while the resistivity increased. The strain of the milled samples was calculated using the Williamson–Hall plot, which increased with the increase of the milling time. The surface layer with large defects and the strain led to the decrease of the insulator-metal transition temperature, but the magnetoresistance value within the whole measured temperature range of 80–300 K was remarkably improved, which indicated that it was an effective route to enhance the magnetoresistance value both at low temperature and at high temperature by mechanochemical processing.