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Thermal, structural, optical, dielectric and barocaloric properties at ferroelastic phase transition in trigonal (NH4)(2)SnF6: A new look at the old compound

Описание

Тип публикации: статья из журнала

Год издания: 2016

Идентификатор DOI: 10.1016/j.jfluchem.2015.12.010

Ключевые слова: Fluorides, Structural disorder, Phase transitions, Entropy, Barocaloric effect

Аннотация: Structural phase transition P-3m1 P-1 of the first order and nonferroelectric nature was found in (NH4)(2)SnF6 at about 110 K in the process of thermal, optical, dielectric and X-ray studies. Order-disorder transformation is accompanied by large changes of entropy (Delta S-0 = 16.4J/mol K) and volume (Delta V-0/V approximate to 1%Показать полностью). The structural model associated with three orientations of NH4 tetrahedra in P-3m1 phase and their complete ordering in P-1 phase was suggested with the entropy change (Delta S-0 = 18.3 J/mol K) close to the experimental value. A good agreement between baric coefficients measured in a direct way (dT(0)/dp = -157 K/GPa) and evaluated using entropy and volume changes at phase transition (-170 K/GPa) was found. Barocaloric effects in (NH4)(2)SnF6 are comparable with those of known solid state refrigerants and are characterised by a low-pressure need for realising their maximum values. (C) 2015 Elsevier B.V. All rights reserved.

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Издание

Журнал: JOURNAL OF FLUORINE CHEMISTRY

Выпуск журнала: Vol. 183

Номера страниц: 1-9

ISSN журнала: 00221139

Место издания: LAUSANNE

Издатель: ELSEVIER SCIENCE SA

Персоны

  • Flerov Igor N. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia; Siberian fed univ, Inst engn phys & radioelect, Krasnoyarsk 660074, Russia)
  • Kartashev Andrey V. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia; Astafijev Krasnoyarsk State Pedag Univ, Krasnoyarsk 660049, Russia)
  • Gorev Mikhail V. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia; Siberian fed univ, Inst engn phys & radioelect, Krasnoyarsk 660074, Russia)
  • Bogdanov Evgeniy V. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia; Krasnoyarsk State Agrarian Univ, Krasnoyarsk 660049, Russia)
  • Mel'nikova Svetlana V. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia)
  • Molokeev Maxim S. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia; Far Eastern State Transport Univ, Khabarovsk 680021, Russia)
  • Pogoreltsev Evgeniy I. (RAS, Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia; Siberian fed univ, Inst engn phys & radioelect, Krasnoyarsk 660074, Russia)
  • Laptash Natalia M. (RAS, Inst Chem, Far Eastern Branch, Vladivostok 690022, Russia)

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