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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 >EPR study of RLi2O.V2O5, RNa2O.V2O5, RCaO.V2O5, and RBaO.V2O5 modified vanadate glass systems
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EPR study of RLi2O.V2O5, RNa2O.V2O5, RCaO.V2O5, and RBaO.V2O5 modified vanadate glass systems

机译：RLi2O.V2O5，RNa2O.V2O5，RCaO.V2O5和RBaO.V2O5改性钒酸盐玻璃系统的EPR研究

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Experimental EPR spectra in several modified vanadate glass systems reveal hyperfine structure (hfs) lines whose widths vary with the molar ratio of modifier to vanadium pentoxide, R. In the RNa2O.V2O5 system, for example, hfs lines show no resolution at low R values (near 0.1); by contrast, these lines exhibit dramatic narrowing as R approaches 0.5. In the model proposed here, this narrowing is due to an increase in hopping time for small polarons associated with V4+ ions in these systems. Increases in polaron hopping times are accompanied by increases in electron spin-spin relaxation times T2's, and, an associated narrowing of EPR linewidths. Experiments confirm that spectral widths are limited by electron T2's due to the fact that EPR linewidths do not vary with temperature down to 4.2K. Resolved spectra in RNa2O.V2O5 at R=0.5 reveal a hyperfine coupling parameter of 0.01770.0008T, corresponding to an upper-limit polaron hopping frequency of 48720MHz. By similar analyses, the systems of RCaO.V2O5, RBaO.V2O5, and RLi2O.V2O5 exhibit comparable polaron hopping frequencies limits of 48020MHz, 46920MHz, and 46820MHz, respectively, when R is near 1.0. In addition to the relaxation effects discussed here, results of modeling of resolved spectra to obtain hyperfine coupling constants A and A[upper left and right quadrants], and g[upper left and right quadrants] values g and g[upper left and right quadrants] are presented and discussed.
机译：在几种改性的钒酸盐玻璃系统中的实验EPR光谱显示超细结构（hfs）线，其宽度随改性剂与五氧化二钒R的摩尔比而变化。例如，在RNa2O.V2O5系统中，hfs线在低R值下无分辨率（0.1附近）;相反，当R接近0.5时，这些线会急剧变窄。在此处提出的模型中，这种变窄是由于这些系统中与V4 +离子相关的小极化子的跳跃时间增加所致。极化子跳跃时间的增加伴随着电子自旋自旋弛豫时间T2的增加，以及随之而来的EPR线宽变窄。实验证实，由于EPR线宽不会随温度降低至4.2K而变化，因此光谱宽度受到电子T2的限制。 RNa2O.V2O5中R = 0.5时的分辨光谱显示出0.01770.0008T的超精细耦合参数，对应于上限极化子跳跃频率48720MHz。通过类似的分析，当R接近1.0时，RCaO.V2O5，RBaO.V2O5和RLi2O.V2O5的系统分别具有可比较的极化子跳跃频率极限，分别为48020MHz，46920MHz和46820MHz。除了这里讨论的弛豫效果之外，解析光谱的建模结果还获得了超精细耦合常数A和A [左和右上象限]，以及g [左和右上象限]值g和g [左和右上象限]提出和讨论。

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