Structure and dielectric properties of solid solutions Bi7−2xNd2xTi4NbO21(x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0)

Abstract

The electrophysical and structural characteristics of bismuth titanate oxides of a number of phases of solid solutions of the Aurivillius phases Bi7−2xNd2xTi4NbO21 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) having a layered structure of the perovskite type have been investigated. According to the XRD data, all studied compounds are single-phase and have a mixed-layer structure of Aurivillius phases (m = 2.5) with a rhombic crystal lattice (space group I2cm, Z = 2). A relationship has been established between changes in the chemical composition of solid solutions and orthorhombic and tetragonal distortions of perovskite-like layers. The temperature dependences of the relative permittivity 𝜀/𝜀o(T) are measured. It was found that the change in the phase transition temperature — Curie temperature TC synthesized Aurivillius phases Bi7−xNd2xTi4NbO21 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) has a close to linear dependence on the change in the parameter x. The activation energies of charge carriers in different temperature ranges were calculated. It was found that three clearly defined temperature ranges with different activation energies can be distinguished, which is associated with the different nature of charge carriers in the studied solid solutions of the perovskite type. The effect of substitution of Nd3+ ions for Bi3+ ions is investigated.

Keywords

• aurivillius phases
• bi7−2xnd2xti4nbo21
• curie temperature (tc)
• tolerance factor