title: Large electrocaloric effects in single-crystal ammonium sulfate.
abstract: Electrocaloric (EC) effects are typically studied near phase transitions in ceramic and polymer materials. Here, we investigate EC effects in an inorganic salt, namely ammonium sulfate (NH4)2SO4, with an order-disorder transition whose onset occurs at 223 K on cooling. For a single crystal thinned to 50 μm, we use a Maxwell relation to find a large isothermal entropy change of 30 J K(-1) kg(-1) in response to a field change of 400 kV cm(-1) The Clausius-Clapeyron equation implies a corresponding adiabatic temperature change of 4.5 K.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.
authors.affiliation: Materials Science, University of Cambridge, Cambridge CB3 0FS, UK.
authors.forename: S
authors.identifier: 0000-0002-4187-5079
authors.initials: S
authors.lastname: Crossley
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.affiliation: Materials Science, University of Cambridge, Cambridge CB3 0FS, UK.
authors.forename: X
authors.initials: X
authors.lastname: Moya
authors.affiliation: Materials Science, University of Cambridge, Cambridge CB3 0FS, UK ndm12@cam.ac.uk.
authors.forename: N D
authors.initials: ND
authors.lastname: Mathur
keywords: ammonium sulfate; electrocaloric effect; phase transition