High temperature impedance properties and conduction mechanism of W6+-doped CaBi4Ti4O15 Aurivillius piezoceramics

Abstract

Effects of W6+ doping on the phase structural and electrical properties, especially the conduction mechanism at a higher temperature of CaBi4Ti4O15 Aurivillius piezoceramics, have been investigated systematically. The conductivity properties at a temperature range from 500 °C to 650 °C have been characterized by complex impedance spectroscopy. The conductivity shows a nature of ionic conduction mechanism and non-Debye relaxation process at a higher temperature. The non-Debye relaxation behavior and conduction process are dominated by the jump of charge carriers, which can be demonstrated by the similar values of the relaxation activation energy (1.45 eV), hopping conduction energy (1.50 eV), and dc conduction energy (1.39 eV). Meanwhile, the piezoelectric coefficient d33 of CaBi4Ti4O15 has been improved from 7.5 pC/N to 17.8 pC/N and keeps good temperature stability up to 650 °C with appropriate W6+ doping. These results provide a profound insight into the conduction process and mechanism from the viewpoint of microstructure, which is greatly beneficial for the high-temperature application of Aurivillius piezoceramics.