Diffuse phase transition was found in barium titanate (BT) thin films with a thickness of 300 nm prepared by a sol–gel method. The electrocaloric effect of these BT thin films was also investigated under a sweep electrical field of 216.7 kV cm−1. Interestingly, it was found that the electrocaloric temperature change (ΔT) increased with a decrease in temperature when the temperature was below 310 K. The novel electrocaloric phenomenon observed in BT thin films with a diffuse phase transition is significant in studying the room temperature electrocaloric effect, which is promising in the refrigeration industry.
