Combustion technique synthesis of lead-free piezoelectric bismuth sodium titanate-bismuth potassium titanate–barium titanate ceramics

Abstract

Fabrication of lead-free piezoelectric ceramic bismuth sodium titanate–bismuth potassium titanate–barium titanate, focusing on the morphotropic phase boundary (MPB) between the rhombohedral and tetragonal phases was studied. a[0.935(Bi0.5Na0.5)TiO3-0.065BaTiO3]-(1-a)[0.8(Bi0.5Na0.5)TiO3-0.2(Bi0.5K0.5)TiO3]; BNBK ceramics with 0 ≤ a ≤ 1 were successfully fabricated using the combustion technique. All BNBK samples were sintered at 1150 °C for 2 h. The effect of a changing on the phase formation, microstructure, dielectric properties and piezoelectric properties of perovskite BNBK ceramics were investigated. XRD results of BNBK ceramics with 0 ≤ a ≤ 1 showed the rhombohedral-tetragonal morphotropic phase boundary (MPB). The SEM results showed the average grain size is between 1.18 and 2.56 µm. The effect of the a content had no influence on the tendency of grain sizes. The maximum density, shrinkage, dielectric constant at Curie temperature (ϵr), remanent polarization (Pr), coercive field (Ec) and piezoelectric constant (d33) were found from BNBK ceramic with a = 1, which is around 5.76 g/cm3, 18.43%, 6503, 15.4 μC/cm2, 20.1 kV/cm and 289 pC/N, respectively.