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采用溶胶凝胶法制备了Ti1-xCrxO2±δ体系系列样品.利用扫描电子显微镜(SEM),X射线光电子能谱(XPS),粉末X射线衍射分析(XRD)方法研究了Ti1-xCrxO2±δ系列样品的颗粒尺寸、形貌、组分化学态、相关系和固溶区范围;并利用超导量子干涉磁强计对样品的磁性能进行了研究.采用Rietveld结构精修的方法研究了Cr的不同掺杂量对TiO2晶体结构的影响,研究表明,1000℃烧结的样品的固溶区范围是x=0—0.03,为金红石单相;随着Cr掺杂量的增加,金红石相晶胞参数规律性地减小;当x>0.03,为金红石相和CrO2相两相共存.综合XRD和磁性测量结果,500℃烧结的样品的固溶区范围是x=0—0.02,为锐钛矿单相;随着Cr掺杂量的增加,锐钛矿相晶胞参数规律性地减小;当x≥0.04,为锐钛矿相和绿铬矿相(Cr2O3)两相共存.XPS实验结果表明,500℃和1000℃退火的样品中Cr都是以Cr+3和Cr+6两种化学态存在,1000℃烧结的样品中可能有更多的Cr3+转化为Cr6+.根据M-H和M-T曲线的测试结果发现,本文500℃烧结的Ti1-xCrxO2±δ体系样品当x=0—0.02时,为室温铁磁性.当x≥0.04时,由铁磁相和顺磁相所组成,在低温下有较强的铁磁性;室温下主要是顺磁相,铁磁相只占据很小的体积分数.
A series of Ti1-xCrxO2 ± δ series samples were prepared by sol-gel method.The structures of Ti1-xCrxO2 ± δ series were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD) The particle size, morphology, compositional chemical state, phase relationship and the range of solid solution zone of the sample were investigated. The magnetic properties of the samples were investigated by using the superconducting quantum interference magnetometer.The Rietveld structure refinement method was used to study the effect of Cr The effects of different doping amount on the crystal structure of TiO2 were studied. The results show that the solid solution zone of sample sintered at 1000 ℃ is x = 0-0.03, which is rutile single phase. With the increase of Cr doping amount, the cell parameters of rutile phase The results show that the rutile phase and the CrO2 phase coexist when x> 0.03.The results of XRD and magnetic measurements show that the range of the solid solution of the sample sintered at 500 ℃ is x = 0-0.02, Phase.With the increase of Cr doping, the cell parameters of anatase phase decreases regularly.When x≥0.04, the two phases coexist in anatase phase and green chrome phase (Cr2O3) .The results of XPS experiment Cr in samples annealed at 500 ℃ and 1000 ℃ are present in two chemical states, Cr + 3 and Cr + 6, and the samples sintered at 1000 ℃ According to the results of MH and MT curves, the samples of Ti1-xCrxO2 ± δ sintered at 500 ℃ are room temperature ferromagnetism when x = 0-0.02, and when x≥0.04 , Composed of ferromagnetic phase and paramagnetic phase, has strong ferromagnetism at low temperature; paramagnetic phase is mainly at room temperature, and ferromagnetic phase occupies only a small volume fraction.