Structure and properties of Na5FeSi4O12 crystallized from 5Na2O–Fe2O3–8SiO2 glass

AHMADZADEH, M, OLDS, TA, SCRIMSHIRE, Alex, BINGHAM, Paul and MCCLOY, JS (2018). Structure and properties of Na5FeSi4O12 crystallized from 5Na2O–Fe2O3–8SiO2 glass. Acta Crystallographica Section C: Structural Chemistry, 74 (12), 1595-1602.

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The phase Na5FeSi4O12 [pentasodium iron(III) silicate] crystallizes readily from the Na2O–Fe2O3–SiO2 glass system in a relatively large compositional range. However, its crystal structure and properties have not been studied in detail since its discovery in 1930. In this work, the Na5FeSi4O12 phase was crystallized from a host glass with 5Na2O·Fe2O3·8SiO2 stoichiometry, and both the glass and the crystal were studied. It was found that the Na5FeSi4O12 phase crystallizes at ∼720 °C from the glass and melts at ∼830 °C when heated at a rate of 10 °C min−1. The crystal structure was solved using single-crystal X-ray diffraction and the refined data are reported for the first time for the Na5FeSi4O12 phase. It exhibits trigonal symmetry, space group Rc, with a = 21.418 and c = 12.2911 Å. The Na atoms located between adjacent structural channels exhibit positional disorder and splitting which was only refined by using low-temperature data collection (150 K). While ∼7% of the total Fe cations occur as Fe2+ in the glass, four-coordinated Fe3+ constitutes ∼93% of the total Fe cations. However, iron in the crystal, which exhibits a paramagnetic behavior, is solely present as six-coordinated Fe3+. The magnetic and vibrational properties of the glass and crystal are discussed to provide additional insight into the structure.

Item Type: Article
Identification Number:
Page Range: 1595-1602
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 14 Dec 2018 11:29
Last Modified: 18 Mar 2021 07:08

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