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- Title
Role of defects in enhancing room temperature ferromagnetism of Mn doped ZnO nanoparticles.
- Authors
Ekhande, L. V.; Dhas, V. V.; Kolekar, Y. D.; Ghosh, K.; Date, S. K.; Patil, S. I.
- Abstract
The soft chemical route was used in the synthesis of undoped and 5% Mn doped ZnO nanocrystalline powders. XRD, TEM, TGA/DTA, FTIR, and superconducting quantum interference device techniques were used to study the structural, nano/microstructural, thermal decomposition and metastability aspects as a function of calcination temperatures (400-1100 °C) and magnetic properties. The evolution of the major wurtzite phase (ZnO) and minor non-stoichiometric nanocrystalline defect cubic spinel phase (ZnMnO3- δ) at various temperatures is clearly seen. The magnetic hysteresis loop is observed at room temperature in the undoped and doped samples calcined at 400 °C. Interestingly, the hysteresis loop parameters ( Ms, Hc) are found to enhance dramatically as soon as the concentration of the minor phase is large enough up to the calcination temperature 700 °C. In contrast, the magnetic hysteresis loop vanishes slowly for the sample calcined at 1000 °C, it disappears completely. The room temperature ferromagnetic behavior at 400 °C is understood in terms of intrinsic cationic/anionic defects, extrinsic defects associated with the various species chemisorbed on the surface of the nanoparticles of undoped and Mn doped ZnO. During thermal annealing a nanocrysatllline seconadary phase of non-stoichiometric defect cubic spinel ZnMnO3- δ is formed, contributing to the enhancement of ferromagnetic behavior. All our experimental results are discussed in terms of model comparing various structural and localized electronic defects formed in the nanocrystalline powder.
- Subjects
NANOCRYSTALS; SUPERCONDUCTIVITY; QUANTUM theory; MAGNETIC hysteresis
- Publication
Physica Status Solidi (B), 2013, Vol 250, Issue 7, p1389
- ISSN
0370-1972
- Publication type
Article
- DOI
10.1002/pssb.201248567