Сибирский федеральный университет

Тип публикации: статья из журнала

Год издания: 2013

Идентификатор DOI: 10.1016/j.jssc.2013.01.038

Ключевые слова: Phase transitions, Iron fluorides, Defect pyrochlore, Differential scanning calorimeters, Displacive transformation, Narrow temperature ranges, Orthorhombic structures, Phase transition mechanisms, Structural phase transition, Defects, Differential scanning calorimetry, X ray powder diffraction, Fluorine compounds

Аннотация: For the first time, structural phase transitions induced by the temperature were found in A(x)N(x)(II)M((1-x))(III)F(3),,)F-3 fluorides with the defect pyrochlore structure (Fd (3) over barm, Z=8). The room temperature structure of CsFe2F6 was determined using X-ray powder diffraction technique. This phase was found to be ordered with the Pnma space group. The study of the temperature stability of orthorhombic structure by differential scanning calorimeter between 100 K and 700 K has shown a succession of phase transitions. The Pnma (Z=4)-> Imma (Z=4)-> I4(1)/amd (Z=4)-> Fd (3) over barm (Z=8) structural sequence was proposed to occur within a rather narrow temperature range 500-560 K. The mechanism of structural transition has been mainly associated with the rotation of (MF6) octahedra and small displacements of some Fe atoms. This assumption is in good agreement with the low experimental entropy value, which is characteristic for displacive transformations. (C) 2013 Elsevier Inc. All rights reserved.

Журнал: JOURNAL OF SOLID STATE CHEMISTRY

Выпуск журнала: Vol. 200

Номера страниц: 157-164

ISSN журнала: 00224596

Место издания: SAN DIEGO

Издатель: ACADEMIC PRESS INC ELSEVIER SCIENCE

• Molokeev M.S. (Siberian Dept RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia)
• Bogdanov E.V. (Siberian Dept RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia; State Agrarian Univ, Inst Energet & Management Energet Sources, Krasnoyarsk 660049, Russia)
• Misyul S.V. (Siberian Fed Univ, Inst Phys Engn & Radioelect, Krasnoyarsk 660074, Russia)
• Tressaud A. (Univ Bordeaux, CNRS, ICMCB, F-33608 Pessac, France)
• Flerov I.N. (Siberian Dept RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia; Siberian Fed Univ, Inst Phys Engn & Radioelect, Krasnoyarsk 660074, Russia)

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