Magnetic Properties of NiFe2O4Nanoparticles in SiO2Matrix

Autor:	Suvankar Chakraverty, Sanjay Chattopadhyay, Kalyan Mandal, Sanjay Kumar, Subarna Mitra
Rok vydání:	2004
Předmět:	Paramagnetism Magnetization Materials science Physics and Astronomy (miscellaneous) General Engineering Analytical chemistry General Physics and Astronomy Nanoparticle Ferrite (magnet) Particle size Brillouin and Langevin functions Single domain Superparamagnetism
Zdroj:	Japanese Journal of Applied Physics. 43:7782-7787
ISSN:	1347-4065 0021-4922
DOI:	10.1143/jjap.43.7782
Popis:	Inverse spinel NiFe2O4 ferrite nanoparticles (2.5 nm to 25 nm) in SiO2 matrix were prepared by sol–gel method. X-ray diffraction method and Transmission Electron Microscope were used to identify the phase and average particle diameter of the samples. The size dependent magnetic properties were investigated using a vibrating sample magnetometer. Superparamagnetic behaviour was observed at room temperature when the average particle size is less than 6 nm. The Mossbauer spectra change from two-peak to six-peak pattern with the increase of particle size and decrease in temperature. Two sets of sextets in the Mossbauer spectra indicate the presence of Fe ion in tetrahedral as well as octahedral sites. The Langevin function used to explain paramagnetism is found to describe well the magnetization behaviour of these samples consisting of weakly-interacting single domain particles in the superparamagnetic state.
Databáze:	OpenAIRE
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