Enhanced electrocaloric effect by configurational entropy change in (Ba,Sr,Ca,Bi,Li)TiO3 system

We report the effect of configurational entropy (CE) on the electrocaloric (EC) effect of BaxSryCaz(Bi0.5Li0.5)1-x-y-zTiO3 (BSCBLT) (0.627≤x ≤ 0.66, 0.0716≤y ≤ 0.1993, 0.0145≤z ≤ 0.1758) ceramics. All samples were designed to show different CE but the same A-site cation average radius, tolerance factor and cationic size disorder. The samples with x ≤ 0.64 show ferroelectric (FE) relaxor behavior, while x ≥ 0.65 are normal FEs. x = 0.65 shows the maximum EC effects among all samples. Both maximum adiabatic temperature change (ΔTm) and CE vary almost in the same way with increasing x. The anomalous enhancement of ΔTm in x = 0.65 with relatively lower CE compared with that in x = 0.64 can be ascribed to an additional contribution of Ba concentration induced FE to relaxor FE transition in BSCBLT. Our results reveal important evidences of enhanced EC effects by CE and suggest that designing FEs or relaxor FEs with high CE might be an effective route to achieve high EC effects.