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Role of defects in enhancing room temperature ferromagnetism of Mn doped ZnO nanoparticles
Author(s) -
Ekhande L. V.,
Dhas V. V.,
Kolekar Y. D.,
Ghosh K.,
Date S. K.,
Patil S. I.
Publication year - 2013
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201248567
Subject(s) - materials science , nanocrystalline material , spinel , wurtzite crystal structure , calcination , ferromagnetism , magnetic hysteresis , nanoparticle , doping , annealing (glass) , phase (matter) , magnetization , analytical chemistry (journal) , chemical engineering , nanotechnology , condensed matter physics , metallurgy , optoelectronics , zinc , chemistry , magnetic field , biochemistry , physics , organic chemistry , quantum mechanics , chromatography , engineering , catalysis
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 (ZnMnO 3– 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 ( M s , H c ) 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 ZnMnO 3– 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.