Effect of La Doping on the Microstructure and Nonlinear Characteristics of CaCu_3Ti_4O_(12) Ceramics

摘要

Ca_(1-x)La_xCu_3Ti_4O_(12) (x=0-0.05) ceramics are prepared by the solid-state reaction method. The effects of La doping on the microstructure and non-Ohmic properties of Ca_(1-x)La_xCu_3Ti_4O_(12) system are investigated by XRD, SEM and Positron annihilation technique. The results show that no phase transition occurs in the doping range (x=0-0.05), while the significant changes in grain size can be observed as x≥0.02. The positron lifetime results prove that the average lifetime is strongly affected by La doping. The correlation of the nonlinear behavior of CaCu_3Ti_4O_(12) system and the grain size, the local electron density in defect was discussed.