Die Kristallstruktur von Germaniumdiselenid

Dittmar, G.; Schäfer, H.

doi:10.1107/s0567740876008704

Cited by 225 publications

(142 citation statements)

References 1 publication

(1 reference statement)

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“…53. On the other hand, low temperature crystalline GeSe 2 has no edgesharing tetrahedral 35 , but glassy GeSe 2 exhibits a companion Raman line associated with edge-sharing tetrahedra 4 ).…”

Section: B Constraint Free Energymentioning

confidence: 99%

Rings and rigidity transitions in network glasses

2003

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Three elastic phases of covalent networks, (I) floppy, (II) isostatically rigid and (III) stressed-rigid have now been identified in glasses at specific degrees of cross-linking (or chemical composition) both in theory and experiments.Here we use size-increasing cluster combinatorics and constraint counting algorithms to study analytically possible consequences of self-organization. In the presence of small rings that can be locally I, II or III, we obtain two transitions instead of the previously reported single percolative transition at the mean coordination numberr = 2.4, one from a floppy to an isostatic rigid phase, and a second one from an isostatic to a stressed rigid phase. The width of the intermediate phase ∆r and the order of the phase transitions depend on the nature of medium range order (relative ring fractions). We compare the results to the Group IV chalcogenides, such as Ge-Se and Si-Se, for which evidence of an intermediate phase has been obtained, and for which estimates of ring fractions can be made from structures of high T crystalline phases.

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Section: B Constraint Free Energymentioning

confidence: 99%

Rings and rigidity transitions in network glasses

2003

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“…The minimum interatomic distances(cut-off) were 3.2, 2.1, 3.1, 2.1, 2.3 and 2.7 Å for Ge-Ge, Ge-Se, Ge-Ag, Se-Se, Se-Ag and Ag-Ag pairs, respectively. The cut-off distances of Ge-Se, Se-Se and Ag-Se correlations were chosen from the corresponding atomic distances (2.36 Å for Ge-Se, 2.34 Å for Se-Se and 2.6 Å for Ag-Se) in the reference materials of crystalline GeSe 2 [13], amorphous Se [14] and glassy Ag 4 Ge 3 Se 9 [15]. The cut-off distances of Ge-Ge and Ag-Ge were set around the deep valley in g(r).…”

Section: Lam14mentioning

confidence: 99%

Local Structure of Superionic Glass Ag_x(GeSe₃)_1-x,x=0.565

Kumara

Ohara

Kawakita

et al. 2011

EPJ Web of Conferences

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Abstract. To investigate relation between inhomogeneous structure of Ag x (GeSe 3 ) 1-x superionic glass and conduction path formation, x-ray diffraction, neutron diffraction and EXAFS measurements on K-edges for each constituent were performed. Reverse Monte Carlo structural modelling based on these experimental data revealed that Ag conduction paths are formed in random glass media of GeSe 4 tetrahedral network. The first sharp diffraction peak (FSDP) located at 1.1 Å -1 is mainly contributed by GeSe 4 network, while an observed intense small angle scattering is contributed also by Ag-Ag as well as GeSe 4 network.

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“…The second model is based on structural fragments proper to hightemperature modification of crystalline GeSe 2 , consisting of two edge-shared (ES) tetrahedra connected with four corner-shared (CS) ones (Fig. 1) [8,20]. According to [15], the structure of Ge x Se 100-x glasses with x < 12 is defined mainly by "chains crossing" model (within ~5-6 % accuracy bar), those with 12 ≤ x ≤ 20 by mixing "chains crossing" and "outrigger raft" models and, finally, the glasses with x > 20 are structured only by "outrigger raft" concept.…”

Section: Resultsmentioning

confidence: 99%

Cluster modeling of quasi‐adaptive phases in vitreous germanium selenides

Shpotyuk

Golovchak

Boyko

et al. 2010

Phys. Status Solidi (c)

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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 Gex Se100‐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 Gex Se100‐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 Gex Se100‐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. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Die Kristallstruktur von Germaniumdiselenid

Cited by 225 publications

References 1 publication

Rings and rigidity transitions in network glasses

Rings and rigidity transitions in network glasses

Local Structure of Superionic Glass Ag_x(GeSe₃)_1-x,x=0.565

Cluster modeling of quasi‐adaptive phases in vitreous germanium selenides

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Die Kristallstruktur von Germaniumdiselenid

Cited by 225 publications

References 1 publication

Rings and rigidity transitions in network glasses

Rings and rigidity transitions in network glasses

Local Structure of Superionic Glass Agx(GeSe3)1-x,x=0.565

Cluster modeling of quasi‐adaptive phases in vitreous germanium selenides

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Local Structure of Superionic Glass Ag_x(GeSe₃)_1-x,x=0.565