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Publication Citation: Nickel-Silica Nanocomposite: Variation of the Blocking Temperature With Magnetic Field and Measuring Frequency

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Author(s): V Singh; M Seehra; John E. Bonevich;
Title: Nickel-Silica Nanocomposite: Variation of the Blocking Temperature With Magnetic Field and Measuring Frequency
Published: February 27, 2008
Abstract: The variation of the blocking temperature T(subscript B) with measuring frequency f(subscript m) and applied field H are reported for Ni nanoparticles (NPs) embedded in SiO(subscript 2) matrix with the nominal composition Ni/SiO(subscript 2) (15/85). Transmission electron microscopy (TEM) of the sol-gel prepared NPs yielded a log-normal distribution with diameter D=3.8(0.2)nm whereas x-ray diffraction data yielded d~3.3nm. The T(subscript B) vs f(subscript m) variation for f(subscript m)=0.1 to 1000 Hz fits the equation T(subscript B)=T(subscript a)/In(f(subscript 0)/f(subscript m)) with f(subscript 0)=2.6x10(superscript 5) A/m (3200Oe) and m = 2(3/2) for lower(higher) H. These results are compared with the prediction of the Neel-Brown model of magnetic relaxation in non-interacting NPs.
Citation: Journal of Applied Physics
Volume: 103
Issue: #07
Pages: pp. D524 - D536
Keywords: electron microscopy;magnetism;nanoparticle;Neel relaxation;x-ray diffraction
Research Areas: Nanomaterials