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Heat capacity, thermal expansion and barocaloric effect in fluoride K2TaF7

The heat capacity and thermal expansion of potassium heptafluorotantalate were studied. The room temperature phase P 2 1 / c is stable at least to 4 K. The strong first-order phase transition P 2 1 / c - P n m a at T 0 = 486.2 K is accompanied by giant changes in the entropy, Δ S 0 = 22.3 J ( mol K...

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Bibliographic Details
Published in:Journal of materials science 2019-12, Vol.54 (23), p.14287-14295
Main Authors: Flerov, I. N., Gorev, M. V., Kartashev, A. V., Pogorel’tsev, E. I., Laptash, N. M.
Format: Article
Language:English
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Summary:The heat capacity and thermal expansion of potassium heptafluorotantalate were studied. The room temperature phase P 2 1 / c is stable at least to 4 K. The strong first-order phase transition P 2 1 / c - P n m a at T 0 = 486.2 K is accompanied by giant changes in the entropy, Δ S 0 = 22.3 J ( mol K ) - 1 , and volume strain, δ V 0 / V = - 3.6 % . A rather high sensitivity of K 2 TaF 7 to pressure was found, d T 0 / d p = - 220 K G Pa - 1 . Significant extensive and intensive barocaloric effects are found at low pressure. The possibility of improving the barocaloric properties is discussed.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-019-03924-8