Band gap, piezoelectricity and temperature dependence of differential permittivity and energy storage density of PZT with different Zr/Ti ratios

Pb (Zr,Ti)O3, (PZT) with Zr/Ti ratio 36/64, 44/56, 52/48, 60/40 and 68/32 are prepared to study the dependence of band gap, energy storage density and differential permittivity on Zr/Ti ratio. Band gaps of the samples are calculated by Kubelka-Munk plots from the Diffuse Reflectance Spectroscopy. The nature of the dependence of band gap on Zr/Ti ratio follows a theoretical model. Comparative studies on the dielectric, ferroelectric and piezo-electric properties are performed. Differential permittivity (DP) is calculated in the temperature range, 30 °C-200 °C. The DP is found to depend strongly on the electric field, temperature and Zr/Ti ratio. Similarly, the change in recoverable energy storage density (ΔJ) with temperature and Zr/Ti ratio is also investigated systematically. At room temperature, the value of ΔJ is observed to be as high as 64.4 mJ/cm3 at an applied field of 30 kV/cm for PZT (36/64) sample. The value of ΔJ decreases with Zr-content and increases with temperature up to 200 °C (experimental limitation) for PZT (36/64), PZT (44/56) and PZT (52/48) whereas the value stops increasing around 190 and 180 °C for PZT (60/40) and PZT (68/32). The highest value of ΔJ is observed to be 172.23 mJ/cm3 at 200 °C for PZT (36/64).