Cluster modeling of quasi-adaptive phases in vitreous germanium selenides

O. Shpotyuk, R. Golovchak, V. Boyko, and S. Kozyukhin.

Physica Status Solidi C, vol. 7, No. 3–4, 2010, p. 921– 924.


The developed cluster modeling approach based on ab-initio calculations with RHF/6-311G* basis set testifies absence of intermediate optimally-constrained phase in binary GexSe100-x system within 20 ≤ x < 26 domain. It is shown, that character “outrigger raft” carcass is conserved for all glass compositions within expected reversibility window. Thus, the structure of binary GexSe100-x glasses can be described in terms of “chains crossing” model in case of x < 12, mixed “chains crossing” and “outrigger raft” models in case of 12 ≤ x < 20 and modified “outrigger raft” model in case of x ≥ 20. The expected reversibility window in binary GexSe100-x glasses is shown to be only quasi-adaptive phase, based on “outrigger raft” structural motive with two edge- and four corner-sharing tetrahedra interconnected by optimally-constrained Ge-Se-Se-Ge bridges with extra Se atoms in ring-like configurations replaced Se-Se dimers. The results of quantum mechanics modeling are confirmed well by high-resolution X-ray photoelectron spectroscopy measurements in this system.


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