Broad Distribution of Local Polar States Generates Large Electrothermal Properties in Pb-Free Relaxor Ferroelectrics

Frederick P. Marlton, Sanjib Nayak, Sarangi Venkateshwarlu, Ngai Hang Chan, Jing Kong, Yuanpeng Zhang, Matthew G. Tucker, Mads Ry Vogel Jørgensen, Abhijit Pramanick

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Electrothermal energy conversion provides attractive solutions for global energy management, such as energy harvesting from waste heat using pyroelectric energy conversion (PEC) and efficient cooling of portable electronics or data servers using the electrocaloric effect. Relaxor ferroelectrics are attractive for electrothermal energy conversion because of their large pyroelectric coefficients over a wide temperature range. Although Pb-based relaxors are well-known, toxicity concerns have mandated the intense search for Pb-free alternatives. Here, we engineered (Ba,Ca)TiO3-based relaxors based on a multisite doping strategy, which show promising electrothermal performance, viz. a maximum PEC efficiency of 14% and electrocaloric refrigeration capacity of 115 J/kg. Using local-scale structural analysis, we provide an atomistic model for large electrothermal properties in the newly designed Pb-free ferroelectrics, whereby a temperature-independent continuous distribution of cation displacement directions creates easy pathways for microscopic polarization reorientation. This research provides key structural insight for future atomic-scale engineering of environmentally sustainable ferroelectrics in energy applications.

Original languageEnglish
Pages (from-to)8844-8853
Number of pages10
JournalChemistry of Materials
Volume33
Issue number22
DOIs
StatePublished - Nov 23 2021

Funding

Funding support from CityU (Project Nos. 7005121 and 7005267 and No. 6000688) are gratefully acknowledged. The work described in this paper was fully/partial supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. eg CityU 11306720) F.P.M. and M.R.V.J. thank the Danish National Research Foundation (Center for Materials Crystallography, DNRF93) and the Danish Agency for Science, Technology, and Innovation for funding the instrument center DanScatt. Affiliation with the Center for Integrated Materials Research (iMAT) at Aarhus University is gratefully acknowledged. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Y.Z. and M.T. are supported by Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy (DOE).

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