Raman scattering and phase transitions in (NH4)(3)TiF7

Описание

Тип публикации: статья из журнала

Год издания: 2018

Идентификатор DOI: 10.1002/jrs.5374

Ключевые слова: (NH4)(3)TiF7, lattice dynamics, order-disorder, reconstructive phase transition, symmetry lowering

Аннотация: Raman spectra of (NH4)(3)TiF7 within spectral range 10-3,400cm(-1) at temperatures 8-370K are recorded, which revealed 2 phase transitions at temperatures T-1=355K and T-2=283K. First principles calculations of lattice dynamics and assignment of the observed lines to specific vibrational types are performed. The first phase transitПоказать полностьюion is classified as an order-disorder one. Manifestation of 97cm(-1) vibration (mixed translational [NH4+F7]) evidences the creation of the hydrogen bond between ammonium group and free fluorine atom, indicating to reconstructive type of phase transition an T-2=283K. The emergence of a large number of vibrational lines in Raman spectra at low temperatures proves symmetry lowering of NH4 tetrahedra with the simultaneous ordering of TiF6 octahedra.

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Издание

Журнал: JOURNAL OF RAMAN SPECTROSCOPY

Выпуск журнала: Vol. 49, Is. 7

Номера страниц: 1230-1235

ISSN журнала: 03770486

Место издания: HOBOKEN

Издатель: WILEY

Авторы

  • Gerasimova Y.V. (Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia; Siberian Fed Univ, Inst Engn Phys & Radio Elect, Krasnoyarsk 660079, Russia)
  • Oreshonkov A.S. (Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia; Siberian Fed Univ, Inst Engn Phys & Radio Elect, Krasnoyarsk 660079, Russia)
  • Laptash N.M. (RAS, Inst Chem, Far Eastern Branch, Vladivostok 690022, Russia)
  • Krylov A.S. (Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia)
  • Aliev A.R. (RAS, Dagestan Sci Ctr, Amirkhanov Inst Phys, Makhachkala 367003, Russia)
  • Roginskii E.M. (Russian Acad Sci, Ioffe Inst, St Petersburg 194021, Russia; St Petersburg State Univ, St Petersburg 199034, Russia)

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