Elastic Phases of GexSbxSe100鈥?x Ternary Glasses Driven by Topology

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• 作者：Kapila Gunasekera ; P. Boolchand ; M. Micoulaut
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：August 29, 2013
• 年：2013
• 卷：117
• 期：34
• 页码：10027-10034
• 全文大小：448K
• 年卷期：v.117,no.34(August 29, 2013)
• ISSN：1520-5207

文摘

Topology offers a practical set of computational tools to accurately predict certain physical and chemical properties of materials including transformations under deformation. In network glasses with increased cross-linking three generic elastic phases are observed. We examine ternary Ge_xSb_xSe_100鈥?x glasses in Raman scattering, modulated DSC and volumetric measurements, and observe the rigidity transition, x = x_c(1) = 14.9% that separates the flexible phase from the Intermediate phase, and the stress transition, x = x_c(2) = 17.5% that separate the intermediate phase from the stressed rigid one. Raman scattering provides evidence of the structural motifs populated in these networks. Using size increasing cluster agglomeration, we have calculated the rigidity and stress transitions to occur near x_c(1)^t = 15.2% and x_c(2)^t = 17.5%, respectively. Theory predicts and experiments confirm that these two transitions will coalesce if edge鈥搒haring Ge-tetrahedral motifs were absent in the structure, a circumstance that prevails in the Ge-deficient Ge₇Sb_xSe_93-x ternary, underscoring the central role played by topology in network glasses. We have constructed a global elastic phase diagram of the Ge鈥揝b鈥揝e ternary that provides a roadmap to network functionality. In this diagram, regions labeled A, B, and C comprise networks that are flexible, rigid but unstressed, and stressed-rigid, respectively.