/ M. S. Molokeev [et al.]> // J. Solid State Chem. - 2013. -
Vol. 200. - P. 157-164
DOI 10.1016/j.jssc.2013.01.038
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Аннотация: For the first time, structural phase transitions induced by the temperature were found in AxMxIIM(1−x)IIIF3 fluorides with the defect pyrochlore structure (Fdm, 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)→I41/amd (Z=4)→Fdm (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.
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Держатели документа: Siberian Dept RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia
State Agrarian Univ, Inst Energet & Management Energet Sources, Krasnoyarsk 660049, Russia
Siberian Fed Univ, Inst Phys Engn & Radioelect, Krasnoyarsk 660074, Russia
Univ Bordeaux, CNRS, ICMCB, F-33608 Pessac, France
Доп.точки доступа: Molokeev, M. S.; Молокеев, Максим Сергеевич; Bogdanov, E. V.; Богданов, Евгений Витальевич;
Misyul, S. V.; Мисюль, Сергей Валентинович; Tressaud, A.; Flerov, I. N.; Флёров, Игорь Николаевич