کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1483759 1510512 2009 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Carbon covered magnetic nickel nanoparticles embedded in PBT-PTMO polymer: Preparation and magnetic properties
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Carbon covered magnetic nickel nanoparticles embedded in PBT-PTMO polymer: Preparation and magnetic properties
چکیده انگلیسی

Fine particles of a face-centered-cubic phase of Ni covered with a graphite layer were prepared and embedded in a PBT-block-PTMO polymer at a concentration of 0.1 wt%. The mean crystalline size of Ni varied from 8 to 30 nm. A magnetic resonance study of the obtained nanocomposites was carried out in the 4–300 K temperature range using an electron paramagnetic resonance spectrometer. An almost symmetrical and very intense magnetic resonance line was recorded for all the investigated samples. The resonance line was centered at g = 2.253(2) (the resonance field Hr = 3003(1) Gs) and had a peak-to-peak linewidth ΔHpp = 693(2) Gs at room temperature. The amplitude of the resonance line increased with a temperature increase in the low temperature range (T < 40 K) and in the high temperature range (T > 100 K) but was constant at intermediate temperatures. The resonance field Hr decreased and linewidth ΔHpp increased as the temperature decreased from room temperature what was similar to the changes observed for other systems of nanoparticles. The thermal gradient of the resonance field, ΔHr/ΔT, strongly depended on the temperature range. The temperature shift of the resonance field and the linewidth were analyzed in terms of the demagnetizing fields of nonspherical agglomerates. A strong change of linewidth and resonance field was registered below 40 K due to the freezing of the spin system’s dynamical magnetic fluctuations. A comparison was made of the results obtained on the Ni/C with the previous measurements on γ-Fe2O3 nanoparticles embedded in a copolymer.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 355, Issues 24–27, 1 August 2009, Pages 1400–1404
نویسندگان
, , , , , , ,