Enhanced ferroelectricity and electrocaloric effect of Sm modified BSTO with temperature stability near room temperature

Lead-free ferroelectric materials are essential for environment-friendly solid-state cooling technology. In this respect, the electrocaloric effect of lead-free Ba(0.8-x)Sr(0.2)SmxTiO(3) (x = 0.01-0.05) ceramics has been investigated. The Rietveld refinement reveals that all the ceramics exhibit tetragonal symmetry and the tetragonality decreases for x > 0.03, which is the major reason behind the decrease in both isothermal entropy change and adiabatic temperature change. The degree of diffuseness parameter is enhanced by doping of Sm3+, which confirms the formation of polar nanoregion and the enhancement of the electrocaloric effect parameter by adding extra entropy. The relaxor behavior of the prepared samples is also confirmed by estimating the degree of deviation parameter (delta T-m = 77 K) from the (1)/(epsilon r) vs: T curve. So, the temperature stability of the prepared ceramics is improved in a broad temperature window. The highest isothermal entropy change (delta S), adiabatic temperature change (delta T), and electrocaloric strength ((delta T)/ (delta E)) are found to be 1.230 Jkg(-1) K-1, 0.862 K, and 0.028 73 K cm/kV at 316 K, AE respectively, for Ba0.77Sr(0.2)Sm(0.03)TiO(3).