کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1801214 | 1024563 | 2010 | 4 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Temperature dependent coercivity and magnetization of nickel ferrite nanoparticles Temperature dependent coercivity and magnetization of nickel ferrite nanoparticles](/preview/png/1801214.png)
Magnetic nanoparticles of nickel ferrite (size: 24±4 nm) have been synthesized by chemical coprecipitation method using stable ferric and nickel salts. Coercivity of nanoparticles has been found to increase with decrease in temperature of the samples. It has been observed that the coercivity follows a simple model of thermal activation of particle’s moment over the anisotropy barrier in the temperature range (10–300 K), in accordance with Kneller’s law for ferromagnetic materials. Saturation magnetization follows the modified Bloch’s law in the temperature range from 300 to 50 K. However, below 50 K, an abrupt increase in magnetization of nanoparticles was observed. This increase in magnetization at lower temperatures was explained with reference to the presence of freezed surface-spins and some paramagnetic impurities at the shell of nanoparticles that are activated at lower temperatures in core-shell nickel ferrite nanoparticles.
Journal: Journal of Magnetism and Magnetic Materials - Volume 322, Issue 15, August 2010, Pages 2199–2202