Barocaloric Effect in Oxyfluorides Rb₂KTiOF₅ and (NH₄)₂NbOF₅

Abstract

Using the data about the temperature–pressure phase diagram and the phase transition entropy at ambient pressure, intensive ΔT _AD and extensive ΔS _BCE barocaloric effects were estimated near structural order-disorder phase transitions in oxyfluorides Rb₂KTiOF₅ and (NH₄)₂NbOF₅. It was found that hydrostatic pressure is an effective tool to change the entropy of compounds with ordering ionic groups in structure and to realize the significant caloric effects comparable with the values of electro- and magnetocaloric effects, characteristic for a number of materials, considered as promising solid refrigerants.

Keywords:

• Phase transition
• oxyfluoride
• thermal properties
• barocaloric effect

PACS numbers:

• 62.50.-p
• 64.70.K-
• 64.90.+b
• 65.40.+g

Acknowledgments

This work was supported in part by the Krasnoyarsk's regional foundation for support of scientific and scientific-technological investigations and RFBR in the framework of project «Siberia» (grant no. 09-02-98001), and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools (project no. Nsh-1011.2008.2).