摘 要: 用溶胶-凝胶法制备了金红石 Ti 1-x Cr x O 2 (x=0、0.04、0.08) 纳米粉末。磁性测量结果显示, 制备的 Cr 掺杂 金红石 TiO 2 纳米粉末具有室温铁磁性, 样品 x=0.04 和 0.08 的饱和磁化强度 M s 分别为 0.55×10 -3 和 1.6×10 -3 emu/g, (emu/g=4π×10 −7 Wb⋅m/kg)矫顽力 H c 分别为 220 和 40 Oe(Oe=10 3 /(4π)A/m)。 Cr 掺杂量较大的样品的饱和磁化强度 较大, 在 Ar 气中退火可以使粉末呈超顺磁性。Cr2p 区域的密集扫描 X 射线光电子能谱 (XPS)分析显示, 在所 有的样品中 Cr 都是以 Cr 3+ 存在。电子顺磁共振谱 (EPR)分析表明, 样品中的 Cr 3+ 离子仅对其顺磁性有贡献。这 些结果提示, 粉末微弱的室温铁磁性来源于掺杂引入的结构缺陷, 其中, 氧空位起重要作用。 关 键 词: Cr 掺杂 TiO 2 纳米粉末; 室温铁磁性; 结构缺陷; 氧空位 中图分类号: O474; O441 Abstract: Rutile Ti

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... 1-x Cr x O 2 (x=0, 0.04, 0.08) nanopowders were synthesized by the Sol-Gel method. Magnetic measurements indicate that as-prepared Cr-doped rutile TiO 2 nanopowders exhibit room-temperature ferromagnetism with saturation magnetizations M s of 0.55×10 -3 and 1.6×10 -3 emu/g, respectively, for samples x=0.04 and 0.08. And their coercive forces H c are 220 and 40 Oe, respectively. The saturation magnetizations M s increase with increasing Cr doping concentration. Annealed nanopowders in Ar atmosphere are superparamagnetic. The tight scan Cr2p by X-ray photoelectron spectroscopy spectra (XPS) indicates that Cr ions are in the +3 state for all samples. Electron paramagnetic resonance (EPR) spectra indicates that Cr 3+ ions contribute only to paramagnetism. Based on above analysis, slight ferromagnetism of Cr-doped TiO 2 nanopowders at room temperature originates from structural defects introduced by doping Cr ions, where oxygen vacancies play an important role.