Mixed-valence hydrated iron fluoridotitanate: Synthesis, optics and calorimetry | Научно-инновационный портал СФУ

Mixed-valence hydrated iron fluoridotitanate: Synthesis, optics and calorimetry

Тип публикации: статья из журнала

Год издания: 2020

Идентификатор DOI: 10.1016/j.jpcs.2020.109444

Ключевые слова: crystal growth, fluoridotitanate, heat capacity, mixed valence, optical properties, phase transition

Аннотация: Mixed-valence hydrated fluoridotitanate with idealized formula FeTiF6·6H2O is the main product of fluoride processing of natural mineral ilmenite with hydrofluoric acid. Its single crystals were grown and optical and calorimetric experiments were carried out in the temperature range 200–350 K. Charge re-distribution, Fe2+Ti4+ to Fe3+Ti3+, in the compound studied was evident in XPS spectra. A first order ferroelastic phase transition occurs at temperatures T0↓ = 271.5 K, T0↑ = 274 ÷ 275.5 K with the symmetry change P3‾↔ P1‾. The structural transformation is accompanied by the appearance of a very weak optical anisotropy in the slice (001), a small anomaly of the heat capacity (ΔS = 1.5 J/mol K = 0.2R), and positive baric coefficients dT0/dp ≈ 30 ± 10 K/GPa. © 2020 Elsevier Ltd

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Издание

Журнал: Journal of Physics and Chemistry of Solids

Выпуск журнала: Vol. 142

Номера страниц: 109444

ISSN журнала: 00223697

Авторы

  • Mel'nikova S.V. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, 660036, Russian Federation)
  • Laptash N.M. (Institute of Chemistry, Far Eastern Branch of RAS, Vladivostok, 690022, Russian Federation)
  • Gorev M.V. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, 660036, Russian Federation, Siberian Federal University, Krasnoyarsk, 660074, Russian Federation)
  • Pogoreltsev E.I. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, 660036, Russian Federation, Siberian Federal University, Krasnoyarsk, 660074, Russian Federation)

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