Low temperature sintering of (Ba0.85Ca0.15) (Ti0.90Zr0.10)O3 lead-free piezoceramic with the additive of MnO2

Abstract

Lead-free (Ba0.85Ca0.15) (Ti0.90Zr0.10)O3 (15/10 BCZT) piezoelectric ceramics were prepared by a standard solid solution and sintered at different temperature of 1300 °C and 1500 °C at a time. The 15/10BCZT piezoceramics were prepared at 1300 °C sintering temperature by doping different amount of MnO2.The ceramics show a phase transition from a freoelectric tetragonal phase to a rhombohedral and tetragonal ferroelctric phase and to a single rhombohedral phase with increasing MnO2 content. The addition of MnO2 significantly improves the sinterbility of the 15/10BCZT piezoceramics, and reducing the sintering temperature from 1500 °C to 1300 °C by 200 °C but showing comparable piezoelectric properties. With 0.4 mol% of the dopant, ∼96.5% of the theoretical density of the ceramics was achieved with excellent piezoelectric coefficient d33 ~ 534pC/N, which is nearly equal to the value obtained from the ceramics sintered at 1500 °C which has a piezoelectric coefficient d33 ~ 570pC/N, high density (~ 5.59 g/cm3 ), maximum remnant polarization (Pr = 24 μC/cm2 ), relatively large grain size (10.4 μm) and the least coercieve field (Ec = 0.42 kV/mm). However, a high concentration of MnO2 deterioated the properties of the ceramics because of increasing of oxygen vacancies and associated defects. The results indicate that the BCTZ-y mol% MnO2 ceramics are one of the promising lead-free piezoelectric candidates for high temperature applications.