Realization of high-energy density polycrystalline piezoelectric ceramics

Abstract

This letter reports a high energy density piezoelectric material in the system given as: $\mathrm{Pb}{\left[\left({\mathrm{Zr}}_{0.52}{\mathrm{Ti}}_{0.48}\right){\mathrm{O}}_3\right]}_{1-x}{\left[\left({\mathrm{Zn}}_{1∕3}{\mathrm{Nb}}_{2∕3}\right){\mathrm{O}}_3\right]}_x+y\mathrm{Mn}\mathrm{C}{\mathrm{O}}_3$ , where $x=0.1$ and $y$ varies from $0.5\text{to}0.9\mathrm{wt}\%$ . A piezoelectric material with high energy density is characterized by a high product of piezoelectric voltage constant $\left(g\right)$ and piezoelectric strain constant (d). The condition for obtaining large magnitude of $g$ constant was derived to be as $\mid d\mid ={\epsilon }^n$ , where $\epsilon$ is the permittivity of the material and $n$ is constant having lower bound of 0.5. It was found that for all practical polycrystalline piezoelectric ceramic materials the magnitude of $n$ lies in the range of 1.1–1.30 and as the magnitude of $n$ decreases towards unity a giant enhancement in the magnitude of $g$ was obtained. A two step sintering process was developed to optimize a polycrystalline ceramic composition with low magnitude of $n$ . For the optimized composition the value of $g_{33}$ and $d_{33}$ was found to be $55.56\times {10}^{-3}{\mathrm{m}}^2∕\mathrm{C}$ and $291\times {10}^{-12}\mathrm{C}∕\mathrm{N}$ , respectively, yielding the magnitude product $d_{33}\bullet g_{33}$ as $\sim 16168\times {10}^{-15}{\mathrm{m}}^2∕\mathrm{N}$ which is significantly higher than the reported values in literature. The magnitude of $n$ for this composition was calculated to be 1.151. This material is extremely promising for immediate applications in the sensing and energy harvesting.