Quasi-adiabatic calorimeter for direct electrocaloric measurements

Mehmet Sanlialp; Vladimir V Shvartsman; Romain Faye; Maksim O Karabasov; Christian Molin; Sylvia Gebhardt; Emmanuel Defay; Doru C Lupascu

doi:10.1063/1.4997155

Quasi-adiabatic calorimeter for direct electrocaloric measurements

Rev Sci Instrum. 2018 Mar;89(3):034903. doi: 10.1063/1.4997155.

Authors

Mehmet Sanlialp¹, Vladimir V Shvartsman¹, Romain Faye², Maksim O Karabasov¹, Christian Molin³, Sylvia Gebhardt³, Emmanuel Defay², Doru C Lupascu¹

Affiliations

¹ Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstraße 15, 45141 Essen, Germany.
² Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), 41 Rue du Brill, 4422 Belvaux, Luxembourg.
³ Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Winterbergstraße 28, 01277 Dresden, Germany.

PMID: 29604744
DOI: 10.1063/1.4997155

Abstract

The electrocaloric effect (ECE) in ferroelectric materials is a promising candidate for small, effective, low cost, and environmentally friendly solid state cooling applications. Instead of the commonly used indirect estimates based on Maxwell's relations, direct measurements of the ECE are required to obtain reliable values. In this work, we report on a custom-made quasi-adiabatic calorimeter for direct ECE measurements. The ECE is measured for two promising lead-free materials: Ba(Zr_0.12Ti_0.88)O₃ and Ba(Zr_0.2Ti_0.8)O₃ bulk ceramics. Adiabatic temperature changes of ΔT_EC = 0.5 K at 355 K and ΔT_EC = 0.3 K at 314 K were achieved under the application of an electric field of 2 kV/mm for the Ba(Zr_0.12Ti_0.88)O₃ and Ba(Zr_0.2Ti_0.8)O₃ samples, respectively. The quasi-adiabatic ECE measurements reliably match other direct EC measurements using a differential scanning calorimeter or an infrared camera. The data are compared to indirect EC estimations based on Maxwell's relations and show that the indirect measurements typically underestimate the effect to a certain degree.