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Structure and spin dynamics in Cr Doped ZnO

Polycrystalline Zn1-xCrxO (0.01 ≤ x ≤ 0.09) samples synthesized by solid state reaction technique were sintered at different temperatures following slow step sintering schedule. Structural, micro-structural, optical, magnetic properties and homogeneity were investigated using suitable characterisation techniques. Cr2O3 and CrO2 phases have been detected in the XRD patterns and Raman spectra of Zn1-xCrxO samples with x ≥ 0.05. Photoluminescence study has indicated improved optical property of the samples compared to undoped ZnO. While low percentage Cr doped samples showed diamagnetic behaviour, higher percentage doped samples (≥ 5%) exhibited ferromagnetic, paramagnetic and anti-ferromagnetic behaviours depending upon the sintering temperatures. The magnetic properties have been analysed through Electron Spin Resonance study. A g-value of 1.97 indicates Cr in +3
valence state in doped ZnO system. Presence of Cr3+ and Cr4+ in ZnO is understood to facilitate super exchange interactions to promote ferromagnetism at room temperature. ESR study shows improved magnetic homogeneity achieved by slow step sintering process. / Physics / M. Sc. (Physics)

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/22833
Date06 1900
CreatorsAmami, Paul Erhire
ContributorsVallabhapurapu, Vijaya Srinivasu, Das, Jayashree
Source SetsSouth African National ETD Portal
LanguageEnglish
Detected LanguageEnglish
TypeDissertation
Format1 online resource (xii, 91 leaves) : illustrations (some color)

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