  By using the semi-wet synthesis method, lead-free ferroelectric materials
Ba0.9Sr0.1Ti1-xSnxO3 with x = 0, 0.02, 0.05, and 0.10 (abbreviated as BSTS)
were prepared and their structural, electric and electrocaloric properties were
investigated. The X-ray diffraction (XRD) patterns show that the samples
calcined at 950{\deg}C have well crystallized into perovskite structure
suggesting the substitution of Ti4+ by Sn4+ in BST lattice. With increasing
content of Sn, the enhancement of the dielectric permittivity was observed for
(0<x<0.05) and the ferroelectric transition temperature (TC) was found to shift
towards the room temperature (TC = 20{\deg}C for x = 0.10). Direct measurements
of the electrocaloric effect (ECE) were performed on all samples by using the
highresolution calorimeter. It is found that Ba0.9Sr0.1Ti0.95Sn0.05O3 exhibits
a high ECE temperature change of DTEC = 0.188 K at an applied electric field of
only 7 kV/cm. Impedance spectrum analysis of all the samples performed in the
temperature range of 300-360{\deg}C reveals the existence of two relaxation
contributions related to the grain and grain boundaries that are well separated
in frequency. Activation energies of conduction and relaxation processes were
deduced for both contributions in order to determine the conduction mechanism
of the studied compositions.
