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Binary Rare‐Earth Silicate Glasses Near Deep Eutectic: The Case for Sc2O3–SiO2 System.

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Title: Binary Rare‐Earth Silicate Glasses Near Deep Eutectic: The Case for Sc2O3–SiO2 System.
Authors: Everson, Bryce1 (AUTHOR), Chuang, Shih‐Yi1 (AUTHOR), Hung, Ivan2 (AUTHOR), Gan, Zhehong2 (AUTHOR), McCormack, Scott J.1 (AUTHOR), Sen, Sabyasachi1 (AUTHOR) sbsen@ucdavis.edu
Source: Journal of the American Ceramic Society. May2026, Vol. 109 Issue 5, p1-9. 9p.
Subjects: Eutectic structure, Nuclear magnetic resonance spectroscopy, Glass structure, Oxidation states, Raman spectroscopy, Phase separation
Abstract: Homogeneous glass formation in binary rare‐earth silicate systems has thus far been precluded due to the presence of extensive liquid–liquid immiscibility and a strong tendency of these liquids toward crystallization. In this study, we demonstrate homogeneous glass formation in the Sc2O3–SiO2 binary system within a narrow compositional window (37–39 mol% Sc2O3) near a deep eutectic between the compounds Sc2Si2O7 and Sc2SiO5, using containerless laser melting under aerodynamic levitation. The atomic structure of these unusual glasses is investigated using multinuclear (29Si, 45Sc, 17O) solid‐state nuclear magnetic resonance (NMR) and Raman spectroscopy. The spectroscopic results, when taken together, provide a comprehensive picture of the structure of these glasses characterized by pyrosilicate [Si2O7]6− anionic units interconnected by Sc cations in ScO6 coordination polyhedra, via Si–O–Sc linkages. A significant fraction (∼6%) of the oxygen atoms in the structure is present as free oxide (FO) ions in Sc–O–Sc linkages, providing connectivity between the ScO6 polyhedra. The formation of the FO species via oxygen disproportionation reaction is promoted by the uniquely high field strength of the Sc3+ ions, and the resulting structural frustration is hypothesized to suppress crystallization of the stable pyrosilicate phase in these liquids, enabling glass formation in an otherwise non‐glass‐forming binary system. These findings highlight the critical role of rare‐earth cation field strength in controlling oxygen speciation, structure, and glass‐forming ability in this binary silicate system. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Homogeneous glass formation in binary rare‐earth silicate systems has thus far been precluded due to the presence of extensive liquid–liquid immiscibility and a strong tendency of these liquids toward crystallization. In this study, we demonstrate homogeneous glass formation in the Sc2O3–SiO2 binary system within a narrow compositional window (37–39 mol% Sc2O3) near a deep eutectic between the compounds Sc2Si2O7 and Sc2SiO5, using containerless laser melting under aerodynamic levitation. The atomic structure of these unusual glasses is investigated using multinuclear (29Si, 45Sc, 17O) solid‐state nuclear magnetic resonance (NMR) and Raman spectroscopy. The spectroscopic results, when taken together, provide a comprehensive picture of the structure of these glasses characterized by pyrosilicate [Si2O7]6− anionic units interconnected by Sc cations in ScO6 coordination polyhedra, via Si–O–Sc linkages. A significant fraction (∼6%) of the oxygen atoms in the structure is present as free oxide (FO) ions in Sc–O–Sc linkages, providing connectivity between the ScO6 polyhedra. The formation of the FO species via oxygen disproportionation reaction is promoted by the uniquely high field strength of the Sc3+ ions, and the resulting structural frustration is hypothesized to suppress crystallization of the stable pyrosilicate phase in these liquids, enabling glass formation in an otherwise non‐glass‐forming binary system. These findings highlight the critical role of rare‐earth cation field strength in controlling oxygen speciation, structure, and glass‐forming ability in this binary silicate system. [ABSTRACT FROM AUTHOR]
ISSN:00027820
DOI:10.1111/jace.70869