Synchrotron single-crystal XRD, IR-, Raman spectroscopy and high pressure study of synthetic krieselite

E Yu Borovikova; A V Spivak; T V Setkova; P S Kvas; A V Kuzmin; E S Zakharchenko; V S Balitsky; S S Khasanov; V A Lazarenko; P V Dorovatovskii; D M Korshunov; S M Aksenov

doi:10.1016/j.saa.2022.122137

Synchrotron single-crystal XRD, IR-, Raman spectroscopy and high pressure study of synthetic krieselite

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Mar 5:288:122137. doi: 10.1016/j.saa.2022.122137. Epub 2022 Nov 21.

Authors

E Yu Borovikova¹, A V Spivak², T V Setkova³, P S Kvas⁴, A V Kuzmin⁵, E S Zakharchenko⁵, V S Balitsky³, S S Khasanov⁵, V A Lazarenko⁶, P V Dorovatovskii⁶, D M Korshunov⁷, S M Aksenov⁸

Affiliations

¹ Geological Faculty, Lomonosov Moscow State University, Moscow 119991, Russia; Laboratory of Arctic Mineralogy and Material Sciences, Kola Science Centre, Russian Academy of Sciences, Apatity 184209, Russia.
² D.S. Korzhinskii Institute of Experimental Mineralogy of Russian Academy of Sciences, Chernogolovka 142432, Russia. Electronic address: spivak@iem.ac.ru.
³ D.S. Korzhinskii Institute of Experimental Mineralogy of Russian Academy of Sciences, Chernogolovka 142432, Russia.
⁴ Geological Faculty, Lomonosov Moscow State University, Moscow 119991, Russia; D.S. Korzhinskii Institute of Experimental Mineralogy of Russian Academy of Sciences, Chernogolovka 142432, Russia.
⁵ D.S. Korzhinskii Institute of Experimental Mineralogy of Russian Academy of Sciences, Chernogolovka 142432, Russia; Institute of Solid State Physics of Russian Academy of Sciences, Chernogolovka 142432, Russia.
⁶ National Research Center "Kurchatov Institute", Moscow 123182, Russia.
⁷ Geological Institute of Russian Academy of Sciences, Moscow 119017, Russia.
⁸ Laboratory of Arctic Mineralogy and Material Sciences, Kola Science Centre, Russian Academy of Sciences, Apatity 184209, Russia.

PMID: 36462320
DOI: 10.1016/j.saa.2022.122137

Abstract

Spontaneous crystals of krieselite (Ge analogue of topaz) with the chemical formula Al₂[(Ge_0.75Si_0.25)O₄](F_1.63OH_0.37) were synthesized using a thermo-gradient hydrothermal method at a temperature of 600/650 °C and pressure of 100 MPa. The unit cell parameters are: a = 8.9732(8) Å, b = 8.4823(7) Å, c = 4.7379(5) Å, V = 360.62(6) Å³, space group Pnma. The F^-/OH^- content of the samples was refined by FTIR spectroscopy method. Raman spectroscopy showed the main differences between the spectra of krieselite and topaz at the ambient conditions. The assignment of observed and calculated A_g bands (cm^-1) for non-polarized Raman spectra was carried out. Using in situ Raman spectroscopy at high pressures, the dependence of the shift in the position of the main bands of the krieselite Raman spectrum on the pressure was established, and the corresponding paths of pressure induced distortion of crystal structure was assumed. According to the data of Raman spectroscopy, it was revealed that krieselite does not undergo the phase transitions up to 30 GPa. The probable way of crystal structure distortion within the space group Pnma was proposed based on simulation of high-pressure Raman spectra.

Keywords: FTIR; High pressure; Krieselite; Raman spectroscopy; Synthesis; Topaz.