Influence of Grain-Growth Inhibitors on Modified (Ba,Sr)(Sn,Ti)O 3 for Electrocaloric Application.

The paper reports on effect of grain-growth inhibitors MgO, Y 2 O 3 and MnCO 3 as well as Ca modification on the microstructure, dielectric, ferroelectric and electrocaloric (EC) properties of Ba 0.82 Sr 0.18 Sn 0.065 Ti 0.935 O 3 (BSSnT). Furthermore, the effects of the sintering time and temperature on the microstructure and the electrical properties of the most promising material system Ba 0.62 Ca 0.20 Sr 0.18 Sn 0.065 Ti 0.935 O 3 (BCSSnT-20) are investigated. Additions of MgO ( x MgO = 1%), Y 2 O 3 ( x Y 2 O 3 = 0.25%) and MnCO 3 ( x MnCO 3 = 1%) significantly decreased the mean grain size of BSSnT to 0.4 µm, 0.8 µm and 0.4 µm, respectively. Ba 0.62 Ca 0.20 Sr 0.18 Sn 0.065 Ti 0.935 O 3 (BCSSnT-20) gained a homogeneous fine-grained microstructure with an average grain size of 1.5 µm, leading to a maximum electrocaloric temperature change |Δ T EC | of 0.49 K at 40 °C with a broad peak of |Δ T EC | > 0.33 K in the temperature range from 10 °C to 75 °C under an electric field change of 5 V µm -1 . By increasing the sintering temperature of BCSSnT-20 from 1350 °C to 1425 °C, the grain size increased from 1.5 µm to 7.3 µm and the maximum electrocaloric temperature change |Δ T EC | increased from 0.15 K at 35 °C to 0.37 K at 20 °C under an electric field change of 2 V µm -1 . Our results show that under all investigated material systems, BCSSnT-20 is the most promising candidate for future application in multilayer ceramic (MLC) components for EC cooling devices.