English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The crystallization of iron-containing sodium silicate phases holds particular importance, both in the management of high-level nuclear wastes and in geosciences. Here, we study three as-quenched glasses and their heat-treated chemical analogs, NaFeSiO 4 , NaFeSi 2 O 6 , and NaFeSi 3 O 8  (with nominal stoichiometries from feldspathoid, pyroxene, and feldspar mineral groups, i.e., Si/Fe = 1, 2, and 3, respectively) using various techniques. Phase analyses revealed that as-quenched NaFeSiO 4  could not accommodate all Fe in the glass phase (some Fe crystallizes as Fe 3 O 4 ), whereas as-quenched NaFeSi 2 O 6  and NaFeSi 3 O 8  form amorphous glasses. NaFeSi 2 O 6  glass is the only composition that crystallizes into its respective isochemical crystalline polymorph, i.e., aegirine, upon isothermal heat-treatment. As revealed by Mössbauer spectroscopy, iron is predominantly present as fourfold-coordinated Fe 3+  in all glasses, though it is present as sixfold-coordinated Fe 3+  in the aegirine crystals (NaFeSi 2 O 6 ), as expected from crystallography. Thus, Na-Fe silicate can form a crystalline phase in which it is octahedrally coordinated, even though it is mostly tetrahedrally coordinated in the parent glasses. Thermal behavior, magnetic properties, iron redox state (including Fe  K -edge X‑ray absorption), and vibrational properties (Raman spectra) of the above compositions are discussed.

Structure of NaFeSiO 4 , NaFeSi 2 O 6 , and NaFeSi 3 O 8 glasses and glass-ceramics