Oxygen vacancies and electrical properties of different valence ions (W6+, Nb5+, Zr4+, Cr3+) doped Bi4Ti3O12 ceramics

Abstract

Numerous literatures have attested that donor doping in BiT ceramics will inhibit the generation of oxygen vacancies to improve electrical properties, but our study detects an originality that acceptor doped into BiT ceramics can also reduce the concentrate of oxygen vacancies and raise the values of Curie temperature and piezoelectric constant. A serious BiT-based ceramics with different valence transition metal dopants of W6+, Nb5+, Zr4+, Cr3+ were prepared via traditional solid phase method, achieving a high Curie temperature of 680–699 °C and a large piezoelectric constant of 7–17 pC/N. To improve the structural and electrical properties of BiT-based ceramics, this paper researched the concentration of oxygen vacancies with charge compensation effect of ions substitution by investigating the phase composition, microstructure, dielectricity, and conductivity systematically. The results show that all transition metal dopants enter the B-site of BiT ceramics to different extent and Cr partially replace the A-site of BiT ceramics, while the relaxation behavior and conduction mechanism of these ceramics are mainly contributed by the migration of oxygen vacancies. Due to the increase in the number of free electrons formed by donor doping W6+ and Nb5+ into BiT ceramics, the reduction in the number of trapped electrons proffered by equivalent doping Zr4+ that occupied the Ti3+ position and the consumption in the vacancies of Bi and O provided by Cr3+ that occupied the A-site after Bi volatilization, the oxygen vacancies defects of the BiT-based ceramics were decreased after ions doped.