کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9803578 | 1516469 | 2005 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Freeze-dried precursor-based synthesis of new polymetallic oxynitrides, V1âuâzCruMoz(OxNy),V1âuâzCruWz(OxNy), Cr1âuâzMouWz(OxNy) (u, z = 0.2, 0.33, 0.4, 0.6, u + z < 1), and VzCrzMozWz(OxNy) (z = 0.25)
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فلزات و آلیاژها
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Freeze-dried precursor-based synthesis of new polymetallic oxynitrides, V1âuâzCruMoz(OxNy),V1âuâzCruWz(OxNy), Cr1âuâzMouWz(OxNy) (u, z = 0.2, 0.33, 0.4, 0.6, u + z < 1), and VzCrzMozWz(OxNy) (z = 0.25) Freeze-dried precursor-based synthesis of new polymetallic oxynitrides, V1âuâzCruMoz(OxNy),V1âuâzCruWz(OxNy), Cr1âuâzMouWz(OxNy) (u, z = 0.2, 0.33, 0.4, 0.6, u + z < 1), and VzCrzMozWz(OxNy) (z = 0.25)](/preview/png/9803578.png)
چکیده انگلیسی
Interstitial polymetallic oxynitrides in the solid solution series V1âuâzCruMoz(OxNy), V1âuâzCruWz(OxNy) and Cr1âuâzMouWz(OxNy) (u, z = 0.2, 0.33, 0.4, 0.6, u + z < 1), as well as the tetrametallic VzCrzMozWz(OxNy) (z = 0.25) composition, can be obtained by ammonolysis of precursors resulting from the freeze-drying of aqueous solutions of the simple metal salts NH4VO3, (NH4)2CrO4, (NH4)6Mo7O24·4H2O and (NH4)6W12O39·18H2O. A study of the influence of the preparative variables on the outcomes of this procedure is presented. Compounds in the V1âuâzCruMoz(OxNy) series have been prepared as single phases by direct ammonolysis of the respective freeze-dried precursors during 2 h at 1173 K, followed by fast cooling of the samples. In contrast, the preparation of compounds in both the V1âuâzCruWz(OxNy) and the Cr1âuâzMouWz(OxNy) series requires the intermediate formation of crystalline precursors. These last compounds result from thermal treatment in air at 973 K, during 12 h, of the corresponding freeze-dried powders. Then, they were subjected to ammonolysis, during 2 h, at 1123 K (V containing series) or 1173 K (Mo containing series), followed by slow cooling of the samples. The tetrametallic VzCrzMozWz(OxNy) compound also has been prepared as single phase by ammonolysis of the crystalline intermediate at 1073 K, during 2 h, followed by slow cooling. All the compounds in these series have the rock-salt crystal structure, in which the metal atoms are in a face-centred cubic arrangement, with non-metal atoms occupying octahedral interstitial positions. The materials have been characterized by X-ray powder diffraction, elemental analysis, thermogravimetric analysis under oxygen flow and scanning electron microscopy.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Alloys and Compounds - Volume 398, Issues 1â2, 2 August 2005, Pages 289-295
Journal: Journal of Alloys and Compounds - Volume 398, Issues 1â2, 2 August 2005, Pages 289-295
نویسندگان
Abdelouahad El-Himri, Pedro Nuñez, Fernando Sapiña, Aurelio Beltrán,