Investigation of Electric and Electrocaloric Properties for Sm-Doped 71PMN–29PT Ceramics

Sm-doped 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3 ceramics (denoted as xSm-71PMN–29PT, 0 ≤ x ≤ 5 mol. %) were synthesized by sol-gel method. The effects of Sm-doping on the electrical and electrocaloric properties of the 71PMN-29PT were investigated. Among all samples prepared, 3Sm-71PMN–29PT displays the optimal piezoelectric and dielectric properties – piezoelectric coefficient d33 of 1040 pC/N, relative dielectric constant εr of 8078, electromechanical coupling factor kp of 0.60. With the increase of Sm doping amount, the dielectric-peak temperature Tm decreases from 405 K to 318 K. Moreover, the electrocaloric (EC) effect in the related ceramics was calculated via indirect method. Under the electric field of 40 kV/cm, the EC temperature change (ΔT) reach their maximal values when the testing temperature is near Tm. The largest electrocaloric response is found in 71PMN–29PT ceramic at T = 428 K with ΔT = 1.49 K, and the largest room temperature electrocaloric response is found in 5Sm-71PMN–29PT ceramic with ΔT = 0.77 K. The excellent comprehensive electrical properties and room temperature electrocaloric performances make Sm-doped 71PMN–29PT ceramics to be one of the most promising candidates for solid- refrigerator applications.