کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1653353 1007662 2006 4 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Preparation of silica-coated Co–Pt alloy nanoparticles
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد فناوری نانو (نانو تکنولوژی)
پیش نمایش صفحه اول مقاله
Preparation of silica-coated Co–Pt alloy nanoparticles
چکیده انگلیسی

A previously proposed method for silica-coating of Co nanoparticles was extended to silica-coating of Co–Pt alloy nanoparticles. The alloy nanoparticles were prepared from CoCl2 (1.2 × 10− 3 M), H2PtCl6 (1.2 × 10− 3 M), citric acid (4 × 10− 4 M) and NaBH4 (1.2 × 10− 2 M). The silica-coating was performed in aqueous/ethanolic solution with a silane coupling agent, 3-aminopropyltrimethoxysilane (8 × 10− 5 M), and a silica source, tetraethoxyorthosilicate (7.2 × 10− 4 M) in the presence of the alloy nanoparticles. TEM observation and X-ray diffraction measurements revealed that the alloy nanoparticles were coated with silica and consisted of fcc Co–Pt alloy crystallites with crystal sizes of 4.6–10.7 nm. Magnetic properties of the silica-coated particles were strongly dependent on annealing temperature. Maximum values of 1.4 emu/g-sample for saturation magnetization and 450 Oe for coercive field were obtained for the particles annealed at 300 °C. Annealing above 300 °C transformed the crystallite from the alloy to pure Pt probably through oxidation of cobalt in the alloy, resulting in reductions in saturation magnetization and coercive field.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Letters - Volume 60, Issue 16, July 2006, Pages 2046–2049
نویسندگان
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