Large electrocaloric effects in oxide multilayer capacitors over a wide temperature range.

Abstract

Heat pumps based on magnetocaloric and electrocaloric working bodies-in which entropic phase transitions are driven by changes of magnetic and electric field, respectively-use displaceable fluids to establish relatively large temperature spans between loads to be cooled and heat sinks1,2. However, the performance of prototypes is limited because practical magnetocaloric working bodies driven by permanent magnets3-5 and electrocaloric working bodies driven by voltage6-16 display temperature changes of less than 3kelvin. Here we show that high-quality multilayer capacitors of PbSc0.5Ta0.5O3 display large electrocaloric effects over a wide range of starting temperatures when the first-order ferroelectric phase transition is driven supercritically (as verified by Landau theory) above the Curie temperature of 290kelvin by electric fields of 29.0volts per micrometre. Changes of temperature in the large central area of the capacitor peak at 5.5kelvin near room temperature and exceed 3kelvin for starting temperatures that span 176kelvin (complete thermalization would reduce these values from 5.5 to 3.3kelvin and from 176 to 73kelvin). If magnetocaloric working bodies were to be replacedwith multilayer capacitors of PbSc0.5Ta0.5O3,then the established design principles behind magnetocaloric heat pumps could be repurposed for better performance without bulky and expensive permanent magnets.