Interplay of dopants and defects in making Cu doped TiO2 nanoparticle a ferromagnetic semiconductor
作者： Biswajit Choudhury , Amarjyoti Choudhury , Debajit Borah
DOI: 10.1016/J.JALLCOM.2015.06.199
关键词: Electron paramagnetic resonance 、 Materials science 、 Polaron 、 Exchange interaction 、 Ferromagnetism 、 Antiferromagnetism 、 Spin polarization 、 Condensed matter physics 、 Superexchange 、 Magnetization
摘要: Abstract Here we have studied the role of oxygen defects and Cu dopants on ferromagnetism in doped TiO2 nanoparticles with nominal concentration 2%, 4% 6 mol%. Electron paramagnetic resonance (EPR) spectra analysis reveals presence Cu2+ distorted octahedral coordination TiO2. d-states undergo strong p-d coupling valence band O 2p state resulting extended absorption hump visible region. Photoluminescence results reveal defect related emission peaks Room temperature is observed all nanoparticles. Saturation magnetization highest at 4 mol% then there a decrease Ferromagnetism completely disappears calcinations air 450 °C for 8 h. It speculated that both vacancies are involved room ferromagnetism. Spin polarization occurs by formation bound magnetic polaron between electrons Cu2+d-states unpaired spins vacancies. Presence Cu2+-Cu2+d-d exchange interaction Cu2+-O2−-Cu2+ antiferromagnetic superexchange interactions might resulted reduction 6 mol% Cu.
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