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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Universal trend of the Haven ratio in glasses: origin and structural evidences from neutron diffraction and small-angle neutron scattering
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Universal trend of the Haven ratio in glasses: origin and structural evidences from neutron diffraction and small-angle neutron scattering

机译：玻璃中的避风港比率的普遍趋势：中子衍射和小角中子散射的起源和结构证据

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摘要

The Haven ratio H-R exhibits a universal trend in oxide and chalcogenide glassy systems as a function of the mobile ion content x. The ion transport in extremely dilute glasses (x = 30-100 ppm M-1) is uncorrelated (H-R approximate to1), but H-R decreases rapidly with increasing x and remains nearly constant (H-R = 0.2-0.4) at x greater than or equal to 10 at.%. An experimentally verified interpretation of this phenomenon is lacking. Our neutron diffraction (ND) and small-angle neutron scattering experiments carried out over a Q-range of four orders of magnitude, from 3 x 10(3) to 40 Angstrom (-1), for a number of silver chalcogenide glassy systems suggest a structural origin for this universal trend. Glasses from the critical percolation domain (x(c) less than or equal to x less than or equal to 1-3 at.%Ag, where x(e) approximate to 30 ppm Ag is the percolation threshold) are characterised by a random silver distribution. The average Ag-Ag separation distance decreases with increasing x in this domain, leading to an increase in the interionic interactions and thus to a monotonic decrease of H-R. In contrast, glasses from the modifier-controlled domain (x greater than or equal to 10 at./ Ag) are characterised by a non-random Ag distribution. Edge-shared AgX3 pyramids (X = S, Se) form chains, cross-linking chains, sheets, tunnels, etc., depending on the system. and provide preferential conduction pathways. The interionic interactions, however, are controlled by an invariant Ag-Ag second neighbour distance of approximate to3 Angstrom, and so the Haven ratio remains essentially constant. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 37]
机译：避风港比率H-R在氧化物和硫属化物玻璃态体系中呈现出随移动离子含量x的变化的普遍趋势。极稀玻璃（x = 30-100 ppm M-1）中的离子迁移是不相关的（HR大约为1），但是HR随着x的增加而迅速降低，并在x大于或等于x时保持几乎恒定（HR = 0.2-0.4）。至10 at。％。缺乏对此现象进行实验验证的解释。我们的中子衍射（ND）和小角中子散射实验在从3 x 10（3）到40埃（-1）的四个数量级的Q范围内进行，许多银硫属化物玻璃质体系表明这种普遍趋势的结构起源。临界渗滤域（x（c）小于或等于x小于或等于1-3 at。％Ag，其中x（e）近似于30 ppm Ag是渗滤阈值）的玻璃的特征在于随机白银分布。在该区域中，平均Ag-Ag分离距离随着x的增加而减小，从而导致离子间相互作用的增加，从而导致H-R的单调减少。相反，来自改性剂控制域（x大于或等于10 at./Ag）的玻璃的特征在于非随机的Ag分布。取决于系统，边缘共享的AgX3金字塔（X = S，Se）形成链，交联链，薄片，隧道等。并提供优先的传导途径。但是，离子间的相互作用受不变的Ag-Ag第二邻域距离（大约为3埃）控制，因此，避风港比率基本保持恒定。 （C）2001 Elsevier Science B.V.保留所有权利。 [参考：37]

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