Microstructural, mechanical and electrical properties of BT, BZT-BCT, and BNT-BT-BKT ferroelectrics synthesized by mechanochemical route

Abstract

BaTiO3 (BT), 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT), 85.4(Bi0.5Na0.5)TiO3-2.6(BaTiO3)-12(Bi0.5K0.5)TiO3 (BNT-BT-BKT) lead free ferroelectric ceramics were synthesized by high energy ball milling (HEBM) assisted solid-state reaction route. The Crystallite size of the HEBM powders was found to be in the nano-range. XRD, SEM, dielectric, polarization vs. electric field (P-E) loop and mechanical characterizations and analysis of these sintered ceramics were carried out. Lower calcination and sintering temperatures along with better densification with the lower average grain size of these ceramics were optimized and obtained compared to the same systems synthesized by the solid-state reaction route. Enhanced values at room temperature (RT) of εr~2875, 5133, and 1701 and lower values of tanδ~0.013, 0.015, and 0.058 were obtained for BT, BZT-BCT, and BNT-BT-BKT sintered ceramics, respectively. Well saturated P-E loops were obtained for all the ceramics, which confirmed their ferroelectric behaviour. Hardness value ~7.23 GPa, 5.53 GPa, and 5.16 GPa were found for BT, BZT-BCT, and BNT-BT-BKT sintered ceramics, respectively. The temperature coefficient of capacitance, TCC, was obtained within ±15% in the temperature range from RT tõ135 °C for BT ceramics with high εr and low value of tanδ, which suggested its usefulness for multilayer ceramic capacitor (MLCC) applications.