Investigation of structural and diffuse phase transition of new nano lead-free system xBAO – yBZT − (1 − x − y) BCT

Abstract

We present in this article the latest development of single-phase nanocrystalline ceramics, x(BiAlO₃) − y(BaZr_0.2Ti_0.8O₃) − (1 − x − y) (Ba_0.7Ca_0.3TiO₃), abbreviated as xBAO − yBZT − (1 − x − y) BCT with (x, y) = (0, 0.50), (0.01, 0.49), (0.03, 0.47) and (0.1, 0.4), which were prepared using a high-energy ball milling technique. In the current study, BZT − xBCT has been selected as a host system to be incorporated into BiAlO₃. Their properties of structure, relative dielectric permittivity (ε), diffuse phase transition (γ), peak broadening (δ_γ) and deviation from Curie–Weiss law (ΔT_C) were systematically investigated. However, the decreasing trend of Curie temperature (T_c) in the system does not obey the Vegard’s law. Analysis of X-ray diffraction patterns shows the solid solubility of (Bi³⁺, Ca²⁺) into A-site and that of (Zr⁴⁺, Al³⁺) into B-site of pure BaTiO₃ lattice of tetragonal symmetry with space group P4mm. The values of γ (1.75 to 1.63) confirmed that the ceramic has intermediate behavior between the relaxor and normal ferroelectric, which is evaluated by modified Curie–Weiss law. The high value of quality factor (115), when x = 0.01, y = 0.49 at 1-kHz frequency and temperature 323 K (50°C), decreases with the increasing frequency.