Phase transition and PTCR effect in erbium doped BT ceramics

Abstract

In this work the dielectric behavior and the main features of the phase transition of the BaTiO3 and Ba0.99Er0.01TiO3 ceramics were carefully investigated. The temperature and frequency dependences of the erbium doped BaTiO3 ceramics dielectric properties were measured in the temperature and frequency ranges of 25 ºC and 225 ºC and 100 Hz to 10 MHz, respectively. A dielectric anomaly was observed in the ferroelectric-paraelectric phase transition of the Ba0.99Er0.01TiO3 ceramic. By using of the Curie-Weiss, Santos-Eiras' and order parameter local phenomenological model, the phase transition features of the samples was analyzed. All models showed a normal phase transition for the BaTiO3 system, while was not possible to establish the character of the phase transition in Ba0.99Er0.01TiO3 system. The relaxation parameters of conductive processes in ferroelectric materials, analysed in the time domain, did not show any influence on the transition from the ferroelectric to the paraelectric state. Finally, the anomaly observed on the phase transition of the erbium doped BaTiO3 ceramics was associated with the influence of the PTCR effect.