Effect of Zr 4 + on piezoelectric, dielectric and ferroelectric properties of barium calcium titanate lead-free ceramics

Abstract

Ba0.85Ca0.15(Ti1-xZrx)O3(BCTZ) ceramics with x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 were prepared by the solid-state reaction method. Calcination of the powders was carried out at 1100 °C for 4 h and the green pellets were sintered at 1400 °C for 2 h. X-ray diffraction patterns of the sintered pellets showed tetragonal splitting up to x= 0.10 while the mixture of the rhombohedral/cubic phase appeared at higher ZrO22 concentrations. Maximum piezoelectric charge constant d33= 510 pC/N and strain (S= 0.103%) were measured for BCT doped by 0.10 mol ZrO22. Dielectric constant, remnant polarization and saturation polarization also found maxima for this composition. The Curie temperature (TC) of the compositions decreased with increase in ZrO22 concentration and reached 98 °C, 87 °C and 36 °C at x= 0.05, 0.10, 0.15 mol, respectively. The remaining compositions have TC below the room temperature; therefore, they can be used for subzero/cryogenic applications. The scanning electron microscopy study revealed an increase in grain size with increase in ZrO22 concentration and confirmed the complete solubility of ZrO22 in the crystal lattice. Overall, low ZrO22-doped BCT compositions with high d33 could be suitable for low temperature (<80 °C) applications.