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Phase composition and magnetic properties of niobium-iron codoped TiO2 nanoparticles synthesized in Ar/O2 radio-frequency thermal plasma |
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| Authors: | Chenning Zhang Masashi Ikeda Masaaki Isobe Ji-Guang Li Takamasa Ishigaki |
| Institution: | a Materials Processing Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan b Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8502, Japan c Department of Materials Chemistry, Hosei University, Koganei, Tokyo 184-8584, Japan d Superconducting Properties Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan e Department of Chemical Science and Technology, Hosei University, Koganei, Tokyo 184-8584, Japan |
| Abstract: | Nanoparticles of Nb5+-Fe3+ codoped TiO2 with various Nb5+ concentrations (Nb/(Ti+Fe+Nb)=0-10.0 at%) and Fe3+ (Fe/(Ti+Fe+Nb)=0-2.0 at%) were synthesized using Ar/O2 thermal plasma. Dopant content, chemical valence, phase identification, morphology and magnetic properties were determined using several characterization techniques, including inductively coupled plasma-optical emission spectrometer, X-ray photoelectron spectroscopy, X-ray diffraction, UV-vis diffuse reflectance spectrometer, field-emission scanning electron microscopy, transmission electron microscopy and SQUID commercial instrument. The XRD revealed that all the plasma-synthesized powders were exclusively composed of anatase as major phase and rutile. The rutile weight fraction was increased by the substitution of Fe3+ for Ti4+ whereas it was reduced by the Nb5+ doping. The plasma-synthesized Nb5+-Fe3+ codoped TiO2 powders had intrinsic magnetic properties of strongly paramagnetic and feebly ferromagnetic at room temperature. The ferromagnetic properties gradually deteriorated as the Fe3+ concentration was decreased, suggesting that the ferromagnetism was predominated by the phase composition as a carrier-mediated exchange. |
| Keywords: | Anatase Rutile Ferromagnetic Paramagnetic Carrier-mediated exchange |
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