Ni-Substitution Induced Inversion in ZnFe2O4 Seen by Positron Annihilation

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We report in this work about the inversion of the spinel structure of ZnFe2O4 induced by the substitution of Zn2+ by Ni2+ ions. Positron lifetimes were measured in Zn1-xNixFe2O4 with different concentrations (x) of doped Ni2+ ions and a drastic change across x = 0.4 – 0.6 was observed, which is attributed to this transformation. The interchange of positions of the cations on doping leaves a fraction of them unoccupied and these vacancies act as positron trapping centres. Since Ni2+ is smaller in size than Zn2+, defects due to non-stoichiometry are less in NiFe2O4 than in ZnFe2O4. The increase in positron lifetime implies the trapping of positrons being shifted from A- to B-sites and is an indication of the transformation from inverse to normal spinel configuration. Coincidence Doppler broadening measurements supported these findings.

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Edited by:

Jozef Krištiak, Jan Kuriplach and Pradeep K. Pujari

Pages:

219-223

Citation:

P.M.G. Nambissan et al., "Ni-Substitution Induced Inversion in ZnFe2O4 Seen by Positron Annihilation", Materials Science Forum, Vol. 733, pp. 219-223, 2013

Online since:

November 2012

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