Thermo-electrical energy conversions in Bi0.5Na0.5TiO3–BaTiO3 thin films prepared by sol–gel method

Solid solution (1 − x)Bi0.5Na0.5TiO3–xBaTiO3 (BNT–xBT) thin films with x = 0, 0.1, 0.9 and 1.0 are synthesized by sol–gel method. The as-prepared BNT–xBT films are crystallized into a single perovskite phase. The temperature-dependent polarizations of the thin films are measured to characterize their performances in thermo-electrical energy conversions. In BNT–0.1BT it is found that the electro-caloric refrigeration temperature change is 3.3 °C with the application of an electric field of 862 kV/cm at 46 °C. The density of electrical energy generating from a 10 °C temperature variation cycle is 0.68 J/cm3. The results demonstrate that BNT–0.1BT lead-free ferroelectrics are excellent environmental-friendly energy materials for electro-caloric refrigeration and pyroelectric energy harvesting applications near room temperature.

► Bi0.5Na0.5TiO3–xBaTiO3 (BNT–xBT) films are prepared by an improved sol–gel method.
► BNT–0.1BT films exhibit excellent performance in pyroelectric energy generation.
► BNT–0.1BT films show large electro-caloric effect at room temperature.
► The thermo-electrical energy conversion is related with the phase transition.