کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7899828 | 1510355 | 2018 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The structure and properties of xZnO-(67-x)SnO-33P2O5 glasses: (II) Diffraction, NMR, and chromatographic studies
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
Glasses with nominal molar compositions xZnO-(67-x)SnO-33P2O5 were prepared and their structures were determined by 31P MAS-NMR spectroscopy, HPLC, and by X-ray and neutron diffraction. Compositional dependent changes in the thermal and optical properties described in Part I of this study are attributed to changes in the coordination environments of Sn2+- and Zn2+-ions and their effects on the phosphate anionic network. The 31P MAS-NMR and HPLC data reveal broader distributions of P-tetrahedra in glasses with greater ZnO-contents, due to disproportionation reactions of diphosphate anions in the glass melts to form isolated monophosphate anions and larger triphosphate anions, and due to the loss of some phosphate during glass preparation. The diffraction experiments reveal that Zn2+ prefers tetrahedral coordination, whereas Sn2+ is initially incorporated in isolated, three-coordinated sites that convert to four-coordinated sites with greater ZnO contents. These four-coordinated sites must share corners when incorporated into the glass structure and the transition from glasses dominated by isolated SnO3 pyramids to those with subnetworks of (Sn, Zn)O4 polyhedra occurs near xâ¯=â¯20, and is reflected by breaks in the composition-property trends. The second break in properties occurs near xâ¯=â¯40, and reflects both the dominance of the ZnO4 units in the metal subnetwork, as well an increase in the relative numbers of monophosphate anions in the glass structure.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 492, 15 July 2018, Pages 68-76
Journal: Journal of Non-Crystalline Solids - Volume 492, 15 July 2018, Pages 68-76
نویسندگان
Uwe Hoppe, Akira Saitoh, Grégory Tricot, Parker Freudenberger, Alex C. Hannon, Hiromichi Takebe, Richard K. Brow,