Influence of sintering atmosphere and thermobaric treatment (TBT) on dielectric behaviors of CaCu3Ti4O12 ceramics

Publication date: Available online 14 June 2018Source: Physics Letters AAuthor(s): Ling-Fang Xu, Cong Mao, Vyacheslav V. Marchenkov, Kang Sun, Tatyana V. Dyachkova, Alexander P. Tyutyunnik, Yurii G. Zainulin, Chang-Ping Yang, Shi-Heng LiangAbstractCopper titanate (CaCu3Ti4O12, or CCTO) ceramics sintered in oxygen and vacuum at 1100°C for 12 h have been treated by thermobaric treatment (TBT) at 9 GPa and 1000°C for 10 min and then quenched in liquid nitrogen (LN2). Pure cubic body-centered perovskite-related structure was confirmed from XRD results. Besides, after TBT and quenching, additional minor peaks of TiO2 and Cu were indexed, as well as a little cell volume expansion. A little reduction of the grain size as well as fuzzy grain boundaries can be observed in FE-SEM after TBT. The dielectric constant ε' of CCTO ceramics sintered in oxygen (∼4600 @ 100 Hz) were a half of those treated by TBT and quenching (∼9600 @ 100 Hz), whereas the value decreased almost by an order of magnitude (from 105 to 104) after TBT and quenching for the samples sintered in vacuum. The complex impedance spectra at high temperature showed three semicircles so a three RC model was used to explain the different relaxation regions consisting of grain, grain boundary and domain boundary. Besides, two relaxation peaks appeared in the frequency dependence of the imaginary part of the electric modulus formalism M⁎ and the complex impedance Z⁎. Moreover, the contributions of grain boundaries ca...

Source: Physics Letters A - July 10, 2018 Category: Physics Source Type: research