Shenoy, S D; Joy, P A; Anantharaman, M R(Elsevier, February , 2004)
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Abstract:
Nanosized ZnFe2O4 particles containing traces of a-Fe2O3 by intent were produced by low temperature chemical
coprecipitation methods. These particles were subjected to high-energy ball milling. These were then characterised using
X-ray diffraction, magnetisation and dielectric studies. The effect of milling on zinc ferrite particles have been studied
with a view to ascertaining the anomalous behaviour of these materials in the nanoregime. X-ray diffraction and
magnetisation studies carried out show that these particles are associated with strains and it is the surface effects that
contribute to the magnetisation. Hematite percentage, probably due to decomposition of zinc ferrite, increases with
milling. Dielectric behaviour of these particles is due to interfacial polarisation as proposed by Koops. Also the defects
caused by the milling produce traps in the surface layer contributes to dielectric permittivity via spin polarised electron
tunnelling between grains. The ionic mechanism is enhanced in dielectrics with the rise in temperature which results in
the increase of dielectric permittivity with temperature.
Anantharaman, M R; Jagatheesan, S; Malini, K A; Sindhu, S; Narayanasamy, A; Chinnasamy, C N; Jacobs, J B; Reijne, S; Seshan, K; Smits, R H H; Brongersma, H H(Elsevier, April 14, 1998)
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Abstract:
Zinc ferrite belongs to the class of normal spinels where it is assumed to have a cation distribution of
Zn2`(Fe3`)2(O2~)4, and it is purported to be showing zero net magnetisation. However, there have been recent reports
suggesting that zinc ferrite exhibits anomaly in its magnetisation. Zinc ferrite samples have been prepared by two
di¤erent routes and have been analysed using low energy ion scattering, Mo¬ ssbauer spectroscopy and magnetic
measurements. The results indicate that zinc occupies octahedral sites, contrary to the earlier belief that zinc occupies
only the tetrahedral sites in a normal spinel. The amount of zinc on the B site increases with decrease in particle size. The
LEIS results together with the Mo¬ ssbauer results and the magnetic measurements lead to the conclusion that zinc
occupies the B site and the magnetisation exhibited by ultraÞne particles of zinc is due to short range ordering
Description:
Journal of Magnetism and Magnetic Materials 189 (1998) 83-88