Ferroelectric phase changes and electrocaloric effects in Ba(Zr$_{0.1}$Ti$_{0.9}$)$_{1-x}$) Sn$_x$O$_3$ ceramics solid solution

Abstract : The effect of tin (Sn) incorporation in lead-free Ba(Zr$_{0.1}$Ti$_{0.9}$)O$_3$ ceramics was investigated. Single phases with perovskite structure were identified using X-ray diffraction analysis. Dielectric permittivity and pyroelectric current measurements carried out versus temperature revealed ferroelectric-to-paraelectric structural phase transitions showing intermediate ferroelectric-to-ferroelectric sequence anomalies for low Sn-content compounds. Electrocaloric effects were highlighted by recording P$-$E hysteresis loops as function of temperature and the electrocaloric temperature change $\Delta$T = 0.2 K was evaluated under 8.7 kV cm$^{-1}$ applied electric field. Electrocaloric responsivity of 0.23 K mm kV$^{-1}$ near Curie temperature remained almost constant until x = 0.075 before decreasing for compounds with $x \geq$ 0.1. Basing on pyroelectric measurement, we highlight the presence of one quadruple point in this system where the simultaneous presence of Zr and Sn in BaTiO$_3$ matrix seems to stabilize ferroelectric and electrocaloric behaviors instead of Sn element alone.