Journal of Materials Research

Relaxor ferroelectrics have drawn attention for possible applications in solid-state cooling and thermal energy harvesting, owing to their electrothermal energy conversion properties. Here, we have synthesized and characterized the structure-property correlations of a new Sn- and Nb-doped (Ba,Ca)TiO3 relaxor ferroelectric with large pyroelectric and electrocaloric effects over a broad temperature range. We observed two peaks for the temperature-dependent pyroelectric coefficient: (i) -(partial derivative P/partial derivative T) similar to 563 mu C/(m(2) K) at T similar to 270 K and (ii) -(partial derivative P/partial derivative T) similar to 1021 mu C/(m(2) K) at T similar to 320 K. In addition, a broad peak for electrocaloric temperature change is observed near 320 K with a relative cooling power of similar to 17 J/kg. These properties could be correlated to structural changes observed using X-ray diffraction at two different temperature ranges in the material. Analysis of high-energy X-ray scattering and specific heat capacity data revealed a transition from the cubic to tetragonal phase near T-m similar to 320 K, whereas an additional increase in the tetragonality (c/a) of the polar phase is observed below T-s similar to 270 K. CityUCity University of Hong Kong [7200514, 7004967, 9610377]; Danish National Research FoundationDanmarks Grundforskningsfond [DNRF93]; Danish Research Council for Nature and Universe (Danscatt); European UnionEuropean Union (EU) [778072]; Slovenian Research AgencySlovenian Research Agency - Slovenia [P1-0125]; DOE Office of ScienceUnited States Department of Energy (DOE) [DE-AC02-06CH11357] A.P. gratefully acknowledges funding support from CityU (Project Nos. 7200514, 7004967, and 9610377). M.R.V.J. is grateful for the support by the Danish National Research Foundation (DNRF93), and the Danish Research Council for Nature and Universe (Danscatt). N.N. acknowledges the European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie grant agreement No 778072 and the Slovenian Research Agency under program P1-0125. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. A.P. gratefully acknowledges technical assistance from Mr. Daniel Yau.