We report the synthesis, at 7 GPa and 923 K, and the thermoelastic characterization, up to 16 GPa and 850 K, of a single crystal of Mg-sursassite, Mg5Al5Si6O21(OH)7. In situ high-pressure and high-temperature single-crystal diffraction allowed the study of structural variation at non-ambient conditions and the determination of bulk elastic properties. The refined parameters of a second-order Birch-Murnaghan equation of state (BM-II EoS) are V0 = 446.02(1) Å3 and KT0 = 135.6(7) GPa. The thermal expansion coefficients of a Berman-type EoS are α0 = 3.14 (5)x10^(-5) K^(-1), α1 = 2.50(16)x10^(-8) K^(-2), and V0 = 445.94(3) Å3. For comparison, the P-V EoS is determined for a natural sursassite sample, ideally Mn4Al6Si6O22(OH)6. The refined parameters of BM-II EoS [V0 = 470.2(3) Å3, KT0 = 128(4) GPa] indicate that composition has a minimal effect on elastic properties. The similarity of density and bulk properties of Mg-sursassite if compared to olivine and other anhydrous mantle minerals suggests that this phase could be overseen by geophysical methods.

Thermoelastic parameters of Mg-sursassite and its relevance as a water carrier in subducting slabsIn: AMERICAN MINERALOGIST. - ISSN 0003-004X. - 107:9(2022 Sep 01), pp. 1760-1765. [10.2138/am-2022-8034]

Thermoelastic parameters of Mg-sursassite and its relevance as a water carrier in subducting slabs

S. Milani
Primo
;
P. Fumagalli
Secondo
;
P. Lotti;F. Pagliaro;M. Merlini
Ultimo
2022

Abstract

We report the synthesis, at 7 GPa and 923 K, and the thermoelastic characterization, up to 16 GPa and 850 K, of a single crystal of Mg-sursassite, Mg5Al5Si6O21(OH)7. In situ high-pressure and high-temperature single-crystal diffraction allowed the study of structural variation at non-ambient conditions and the determination of bulk elastic properties. The refined parameters of a second-order Birch-Murnaghan equation of state (BM-II EoS) are V0 = 446.02(1) Å3 and KT0 = 135.6(7) GPa. The thermal expansion coefficients of a Berman-type EoS are α0 = 3.14 (5)x10^(-5) K^(-1), α1 = 2.50(16)x10^(-8) K^(-2), and V0 = 445.94(3) Å3. For comparison, the P-V EoS is determined for a natural sursassite sample, ideally Mn4Al6Si6O22(OH)6. The refined parameters of BM-II EoS [V0 = 470.2(3) Å3, KT0 = 128(4) GPa] indicate that composition has a minimal effect on elastic properties. The similarity of density and bulk properties of Mg-sursassite if compared to olivine and other anhydrous mantle minerals suggests that this phase could be overseen by geophysical methods.
Mg-sursassite; hydrous minerals; crystal structure; thermoelastic parameters
Settore GEO/06 - Mineralogia
Settore GEO/07 - Petrologia e Petrografia
Settore GEO/09 - Georisorse Miner.Appl.Mineral.-Petrogr.per l'amb.e i Beni Cul
DECC18MGIUD_01 - Dipartimenti di Eccellenza 2018-2022 - Dipartimento di SCIENZE DELLA TERRA "ARDITO DESIO" - GIUDICI, MAURO - DECC - Bando Dipartimenti di Eccellenza - 2018
https://www.degruyter.com/document/doi/10.2138/am-2022-8034/html
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/939458
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