Enhancement of dielectric, piezoelectric, ferroelectric, and electrocaloric properties in slightly doped (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramic by samarium

Abstract

We investigated the structural, dielectric, piezoelectric, ferroelectric, and electrocaloric properties of the samarium doped (Na0.5Bi0.5)0.94Ba0.06TiO3 (NBT-6BT) ceramic. X-ray diffraction and Raman spectra confirm the coexistence of the rhombohedral and tetragonal structures for a low amount of Sm (≤8 mol. %), while the compositions with a higher amount of Sm2O3 (11 mol. %) have a pseudocubic structure. The thermal dependency of the dielectric permittivity revealed two phase transitions from ferroelectric to antiferroelectric at low temperatures, then to paraelectric phase at higher temperatures. The substitution of NBT-6BT with 2 mol. % of Sm2O3 remarkably enhances the ferroelectric and the piezoelectric properties of the (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramic. Furthermore, a large electrocaloric effect (ΔT=1.4K) was directly measured on the ceramic doped with 2 mol. % of Sm2O3 under an applied electric field of 50 kV/cm.