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

Abstract

[Formula: see text][Formula: see text]([Formula: see text][Formula: see text][Formula: see text](BCTZ) ceramics with [Formula: see text] 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 [Formula: see text]C for 4 h and the green pellets were sintered at 1400 [Formula: see text]C for 2 h. X-ray diffraction patterns of the sintered pellets showed tetragonal splitting up to [Formula: see text] 0.10 while the mixture of the rhombohedral/cubic phase appeared at higher ZrO2 concentrations. Maximum piezoelectric charge constant [Formula: see text] 510 pC/N and strain ([Formula: see text] 0.103%) were measured for BCT doped by 0.10 mol ZrO2. Dielectric constant, remnant polarization and saturation polarization also found maxima for this composition. The Curie temperature ([Formula: see text] of the compositions decreased with increase in ZrO2 concentration and reached 98 [Formula: see text]C, 87 [Formula: see text]C and 36 [Formula: see text]C at [Formula: see text] 0.05, 0.10, 0.15 mol, respectively. The remaining compositions have [Formula: see text] 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 ZrO2 concentration and confirmed the complete solubility of ZrO2 in the crystal lattice. Overall, low ZrO2-doped BCT compositions with high [Formula: see text] could be suitable for low temperature (<80 [Formula: see text]C) applications.

Keywords

• ZrO2-doped BCT
• lead-free piezoelectrics
• high piezoelectric charge constant
• Curie temperature