کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1464055 989655 2009 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Preparation of zirconium tungstate (ZrW2O8) by the amorphous citrate process
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Preparation of zirconium tungstate (ZrW2O8) by the amorphous citrate process
چکیده انگلیسی

Citrate gels were prepared from aqueous solutions of zirconium dinitrate oxide, ammonium metatungstate and citric acid in the range of pH 1.1–10. The citric acid to total metal molar ratio was varied from 0.66 to 1.33. The thermal decomposition of these precursor gels and the oxide phase evolution were studied by thermal analysis (DTA, TG, EGA-MS) and X-ray powder diffraction (XRD), respectively. Complex stability appeared to be largely insensitive to pH variations, whereas consistency and thermal behaviour of the gels were found to be influenced by pH and molar ratio of the starting solutions. Under optimized thermolysis conditions, phase-pure trigonal ZrW2O8 was obtained which was converted to cubic ZrW2O8 by up-quenching to 1125 °C for a very short time (<1 min). The cubic ZrW2O8 has particle sizes in the lower micron to submicron range and shows a negative linear coefficient of thermal expansion CTE = −10.2 × 10−6 K−1 (30–120 °C). The polymorphism of ZrW2O8 is discussed with respect to its preparation by the amorphous citrate process and other soft chemistry routes.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Ceramics International - Volume 35, Issue 2, March 2009, Pages 755–762
نویسندگان
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