Room-Temperature Ferromagnetism in Semiconducting TiO2-δ Nanoparticles
ZHAO Qian1,2, WU Ping1,2, LI Bao-Ling1,2, LU Zun-Ming3, JIANG En-Yong 1,2
1Department of Applied Physics, Institute of Advanced Materials Physics, School of Science, Tianjin University, Tianjin 3000722Tianjin Key Laboratory of Low-Dimensional Materials Physics and Preparing Technology, Tianjin University, Tianjin 3000723College of Materials, Hebei University of Technology, Tianjin 300130
Room-Temperature Ferromagnetism in Semiconducting TiO2-δ Nanoparticles
1Department of Applied Physics, Institute of Advanced Materials Physics, School of Science, Tianjin University, Tianjin 3000722Tianjin Key Laboratory of Low-Dimensional Materials Physics and Preparing Technology, Tianjin University, Tianjin 3000723College of Materials, Hebei University of Technology, Tianjin 300130
摘要TiO2-δ nanoparticles are synthesized by the sol-gel method and annealed under different reducing atmosphere. The x-ray diffraction patterns show that anatase is the dominant phase with small amounts of the rutile phase of TiO2-δ for all the samples. Magnetic measurements indicate that the samples annealed in reducing atmosphere exhibit inprecedented room-temperature ferromagnetism, in particular, the saturation magnetization Ms is up to about 8.6×10-3emu/g for the sample annealed in H2/Ar mixture. Analysis of the x-ray photoelectron spectroscopy spectra for the samples processed under different conditions indicates that the amounts of Ti3+ or Ti2+ cations, namely, the concentration of oxygen vacancies, increase with intensifying reducing atmosphere during processing, which shows that ferromagnetism in this material strongly depends on the concentration of oxygen vacancies. The relationships between the ferromagnetism and the crystal structure as well as the grain size in this material are also discussed.
Abstract：TiO2-δ nanoparticles are synthesized by the sol-gel method and annealed under different reducing atmosphere. The x-ray diffraction patterns show that anatase is the dominant phase with small amounts of the rutile phase of TiO2-δ for all the samples. Magnetic measurements indicate that the samples annealed in reducing atmosphere exhibit inprecedented room-temperature ferromagnetism, in particular, the saturation magnetization Ms is up to about 8.6×10-3emu/g for the sample annealed in H2/Ar mixture. Analysis of the x-ray photoelectron spectroscopy spectra for the samples processed under different conditions indicates that the amounts of Ti3+ or Ti2+ cations, namely, the concentration of oxygen vacancies, increase with intensifying reducing atmosphere during processing, which shows that ferromagnetism in this material strongly depends on the concentration of oxygen vacancies. The relationships between the ferromagnetism and the crystal structure as well as the grain size in this material are also discussed.
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2008, Vol. 25 
