Piezoelectric, structural, vibration and optical properties of lead free based 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 ceramic sample

Abstract

The single-phase solid solution of 0.5 {Ba (Zr0.2Ti0.8) O3}− 0.5 {(Ba0.7Ca0.3) TiO3} ceramic sample was prepared by solid state method. The X-ray diffraction study confirmed the mixed phases of tetragonal and rhombohedral crystal structure. The average crystallite size was ∼ 90 nm measured from the Williamson Hall plot method. An estimated average grain size ∼ 4.2 µm is obtained from scanning electron microscopy and well-defined grains separated by clear grain boundaries. The band gap for the sample was found ∼2.8 eV from absorption spectra. The red shifting of vibration B1/E(TO3)/E(LO2) mode at low temperature causes the phase transition from tetragonal to rhombohedral and the band E(TO)+A1(TO) at ∼523 cm−1 becomes more broadening and disappears above 300 °C. So sample transfer from tetragonal to cubic phase. The absence of A(LO1) and the softening of A(TO3) modes are attributed to transfer from tetragonal to rhombohedral above − 100 °C at low temperature. The temperature dependence of permittivity value further supports the phase transition from orthorhombic-tetragonal ∼50° C and tetragonal–cubic ∼ 250 °C. The PL spectra revealed disorder and three distinct green peaks (2.85 eV, 2.75 eV, 2.65 eV and 2.54 eV) evidence of rhombohedral structure. P∼E loop exhibits a soft and ferroelectric in nature. A maximum strain of 0.45% field-induced and a large d33 value ∼ 870 pm/V in the ceramics sample.