کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5420920 | 1395482 | 2007 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR](/preview/png/5420920.png)
چکیده انگلیسی
Lithium-containing silicon (oxy)carbonitride ceramics (SiCN(O):Li) were synthesized via precursor-to-ceramic-transformation of Li-containing (poly)silazanes. The precursors were obtained by lithiation of 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane with n-butyllithium and by reaction of a commercial poly(organosilazane) VL20® with metallic lithium. The annealing treatment was carried out at temperatures between 200 and 1400 °C in argon (ÎT=200 °C) and yielded Li-containing silicon (oxy)carbonitride. X-ray powder diffraction revealed that the resulting SiCN(O):Li ceramics were basically amorphous up to temperatures of 1000 °C and formed LiSi2N3, graphite and silicon carbide as crystalline phases at higher temperatures. 7Li MAS NMR spectroscopy was carried out to investigate the structure of the Li-containing phases and to study the reaction path of metallic Li with polysilazane. Based on the NMR spectra, there is almost no difference found in the chemical shift of the SiCN(O):Li ceramics obtained at different temperatures. Accordingly, Li is assigned to be mainly coordinated to N and O present as contaminant element. Relaxation time measurements showed that the most mobile Li+ species seems to be present in the product obtained in the pyrolysis temperature range between 600 and 1000 °C.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Solid State Nuclear Magnetic Resonance - Volume 31, Issue 2, April 2007, Pages 82-90
Journal: Solid State Nuclear Magnetic Resonance - Volume 31, Issue 2, April 2007, Pages 82-90
نویسندگان
Sina Gumann, Nikolaus Nestle, Verena Liebau-Kunzmann, Ralf Riedel,