Mössbauer and magnetic studies in nickel ferrite nanoparticles: Effect of size distribution

Rakesh Malik, S. Annapoorni, Subhalakshmi Lamba, V. Raghavendra Reddy, Ajay Gupta, Parmanand Sharma, Akihisa Inoue

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The magnetic properties of nickel ferrite nanoparticles in the form of powders, prepared by the solgel process and subjected to different annealing temperatures, were investigated using both static and dynamic measurements namely hysteresis, zero field cooledfield cooled magnetization (ZFCFC) measurements and Mssbauer spectroscopy. The Transmission Electron Microscopy (TEM) studies reveal particle sizes ∼28nm for the as-prepared particles which increases upto 52 nm with annealing. A bimodal distribution, upto an annealing temperature of 300°C was observed. ZFCFC measurements for the as-prepared samples reveal twin peaks, indicative of the bimodal size distribution. ZFCFC measurements performed for fields varying from 100 Oe to 3 kOe show a superparamagnetic phase with blocking temperatures between 320 and 85K. Numerical simulations for the ZFCFC studies indicate that the signature of the bimodal size distribution can be seen only at very low fields. The variation of coercivity with particle size, as determined from the hysteresis measurements, shows a transition from a single domain to a multi domain state for particle sizes larger than 35 nm. Mssbauer measurements performed at room temperature for the as-prepared sample shows a six finger pattern for the samples with higher particle size and a doublet pattern for the samples with smaller particle size, which is indicative of their superparamagnetic nature.

Original languageEnglish
Pages (from-to)3742-3747
Number of pages6
JournalJournal of Magnetism and Magnetic Materials
Volume322
Issue number23
DOIs
Publication statusPublished - 2010 Dec 1

Keywords

  • Hysteresis
  • Magnetic nanoparticle
  • Monte Carlo
  • Mssbauer spectroscopy
  • Nickel ferrite

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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