Influence of spark plasma sintering temperature on the microstructures, dielectric and I-V properties of CaCu3Ti4O12 ceramics

摘要

CaCu3Ti4O12 (CCTO) ceramics were prepared by the sol-gel process and sintered by the spark plasma sintering (SPS) process at different temperatures. The SPS process temperature has an important effect on the microtopography of CCTO ceramics. The results of EDS and positron annihilation spectroscopy indicate that Cu2+ diffuses from the inside to the surface of grains during the sintering process at high temperature. The permittivity (epsilon(r)) of CCTO ceramics at the corresponding frequencies increases with increasing SPS temperature. However, the frequency stability of epsilon(r) over the frequency range 40-10(6) Hz wanes gradually. The CCTO ceramics sintered at 900 degrees Cand 950 degrees C present very low dielectric loss values(about 0.02) near 10 kHz. The change in epsilon(r) and tans for CCTO ceramics can be explained by the internal barrier layer capacitance (IBLC) model and AC (alternating current) impedance spectra. The results of I-V nonlinear characteristics for CCTO ceramics make clear that the potential barrier height has a positive effect on the value of nonlinear coefficient. (C) 2020 Elsevier B.V. All rights reserved.