| Autor: |
Mrinal Pal, P.M.G. Nambissan, C. Chakrabarty, Oindrila Mondal |
| Rok vydání: |
2012 |
| Předmět: |
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| Zdroj: |
Materials Science Forum. 733:219-223 |
| ISSN: |
1662-9752 |
| Popis: |
We report in this work about the inversion of the spinel structure of ZnFe2O4induced by the substitution of Zn2+by Ni2+ions. Positron lifetimes were measured in Zn1-xNixFe2O4with 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 NiFe2O4than 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. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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