کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1484884 | 1510528 | 2008 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
O K-edge XANES studies of alkali germanophosphate glasses
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Alkali germanophosphate glasses exhibit a 'germanate anomaly', which is a maximum or minimum in their density profiles with the addition of alkali oxide. Several structural mechanisms have previously been recognized to affect the density behavior of these glasses: (1) depolymerization of the PO4 tetrahedral network; (2) conversion of 4- to 3-membered GeO4 rings and (3) depolymerization of the GeO4 network through the formation of non-bridging oxygens. A coordination change from 4- to 5-fold Ge has been detected in alkali germanate glasses, which also exhibit the germanate anomaly. In this study, oxygen K-edge XANES of alkali germanophosphate glasses is used to investigate the coordination change of Ge with increasing alkali content and at various Ge to P ratios. The dominant peak at â¼538Â eV in the spectra undergoes a shift to lower energy of â¼0.4Â eV, indicating the formation of 5-fold Ge similar to previous studies on alkali germanate glasses. However, the formation of 5-fold Ge does not correlate with the density anomaly compositions of these glasses suggesting that the appearance of higher-coordinated Ge species is not controlling the anomaly behavior.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 354, Issues 10â11, 1 February 2008, Pages 863-872
Journal: Journal of Non-Crystalline Solids - Volume 354, Issues 10â11, 1 February 2008, Pages 863-872
نویسندگان
Halan M. Wang, Grant S. Henderson,