Magnetic relaxation and correlating effective magnetic moment with particle size distribution in maghemite nanoparticles

Size and surface effects in the magnetic properties of maghemite and magnetite coated nanoparticles.

An increasing number of promising applications for future technology is arising from size constraints in nanoparticles (NPs) and from the chemical manipulation of their surfaces. In this work, we analyse the finite-size and surface effects on polyacrylic acid-coated Fe(3)O(4) NPs and oleic acid-coated gamma-Fe(2)O(3) NPs by studying their magnetization curves at different temperatures. The meas...

Anomalous Particle Size Dependence of Magnetic Relaxation Phenomena in Goethite Nanoparticles

By use of Mössbauer spectroscopy we have studied the magnetic properties of samples of goethite nanoparticles with different particle size. The spectra are influenced by fluctuations of the magnetization directions, but the size dependence is not in accordance with the Néel-Brown expression for superparamagnetic relaxation of the magnetization vectors of the particles as a whole. The data sugge...

Influence of particle size on Magnetic behavior of nickel oxide nanoparticles

The influence of the particle size on magnetic behaviors of nickeloxide nanoparticles (NiO NPs) was reported. NiO NPs with a uniform particlesize were synthesized via a facile sol-gel method, and various sizes of NiO NPs(11, to 49 nm) were achieved by calcination at various temperatures (400, to 700°C). X-ray diffraction (XRD) analysis revealed that increasing the calcinationtemperature increas...

Thermoinduced magnetic moment in akaganéite nanoparticles

Magnetic Behaviour of Maghemite Nanoparticles Studied by Mössbauer Spectroscopy

Two systems of nanoparticles with different surface states have been prepared by sol-gel methods and analysed by X-ray diffractometry, transmission electron microscopy, thermal analysis and temperature dependent Mossbauer spectroscopy. Surface states and phase content, particle mean size and the magnetic anisotropy energy constant were evaluated.