| Structural evolution of Ge–Ga–Se glass upon compositional change across the stoichiometric GeSe2–Ga2Se3 tie-line |
Hyun Kim1, Il Jung Yoon1, Bong Yong Jeong2, Yong Gyu Choi1
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1Department of Materials Science and Engineering, Korea Aerospace University, Goyang, Gyeonggi, 10540, Republic of Korea
2Department of Manufacturing Innovation, Inha University, Yeonsu, Incheon, 21999, Republic of Korea |
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Received: March 28, 2024; Revised: May 15, 2024 Accepted: May 25, 2024. Published online: June 7, 2024. |
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| ABSTRACT |
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A compositional series of GexGa10Se90−x (at.%; x = 20, 23.3, 25, 27.5, and 30), set to cross both the stoichiometric GeSe2–Ga2Se3 tie-line and the pseudo-stoichiometric GeSe2–GaSe2 tie-line compositions, is employed in this study to refine the local structural environments of Se atoms. Our structural analysis reconfirms that the amorphous network of Ge25Ga10Se65 glass consists mainly of [Ge(Ga)Se4] tetrahedral units connected through either corner-sharing or edge-sharing, in addition to involvement of threefold-coordinated Se atoms. Interestingly, however, upon increase of Se content up to Ge23.3Ga10Se66.7, which belongs to the pseudo-stoichiometric GeSe2–GaSe2 tie-line, the excess Se atoms turn out to form homopolar –Se–Se– chain fragments rather than to transform the heteropolar threefold-coordinated Se atoms into the typical heteropolar twofold-coordinated Se atoms bridging two tetrahedra. Coexistence of the homopolar twofold-coordinated and heteropolar threefold-coordinated Se atoms is considered a unique structural characteristic of Ge–Ga–Se glass, which needs to be taken into account in the compositional optimization of its macroscopic properties. |
| Key words:
Chalcogenide glass · Ge–Ga–Se glass · Glass structure · Threefold-coordinated chalcogen atoms |
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