Abstract
Bi4Ti3O12 is an important lead-free ferroelectric material. Doping modification of Bi4Ti3O12 has attracted great attention to improving its performances. In this work, the effect of Sr dopants on the microstructure, dielectric, and conductivity of Bi4Ti3O12 ceramic was investigated by XRD, SEM, and AC impedance spectroscopy. Substitution of 1 at% Sr for Bi decreased the grain size, suppressed the dielectric dispersion of Bi4Ti3O12 ceramic at room temperature, and resulted in different effects on the conductivity of grains and grain boundaries. The conductivity of grains in Bi4Ti3O12 ceramic was increased by the small amount of Sr dopants in the whole experimental temperature range. While the grain boundaries of 1 at% Sr-doped Bi4Ti3O12 exhibited lower conductivity than pure Bi4Ti3O12 below ~380 °C and higher conductivity above ~380 °C. The experimental phenomena were interpreted in term of compensating defects for Sr dopants.
Highlights
Bismuth-based layer-structured ferroelectrics (BLSF) known as Aurivillius compounds are generally represented by a formula (An–1BnO3n+1)2–(Bi2O2)2+, where A denotes mono, di, or trivalent cations or a mixture of those at the 12-coordinated site, B stands for tri, tetra, or pentavalent cations at the 6coordinated site, and n indicates the number of perovskite units [1,2]
The results demonstrate that the Sr2+ cations are incorporated into the lattice structure of BIT
Bi4Ti3O12 ceramics doped with small amount Sr ions were synthesized by conventional solid-state reaction route and investigated by temperature dependent AC impedance spectroscopy
Summary
Bismuth-based layer-structured ferroelectrics (BLSF) known as Aurivillius compounds are generally represented by a formula (An–1BnO3n+1)2–(Bi2O2)2+, where A denotes mono-, di-, or trivalent cations or a mixture of those at the 12-coordinated site, B stands for tri-, tetra-, or pentavalent cations at the 6coordinated site, and n indicates the number of perovskite units [1,2]. Aurivillius compounds have not been systematically investigated. The leakage of BIT is believed to be closely related to the oxygen vacancies induced by the evaporation of Bi at the sintering temperature. The aliovalent Sr2+ substitution for Bi3+ can work as acceptors to compensate for the electrons from the ionization of oxygen vacancies, which would further inhibit the leakage of BIT. It is necessary to experimentally investigate the effect of Sr dopants on the conduction of BIT
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