Narrow Band Gap and Room-temperature Ferromagnetism in KNb1-xFexO3-δ  

窄带隙KNb1-xFexO3—δ的室温铁磁性

作　　者：Dan Nie Jiang Zhang Wen-ji Deng Xi Chen Zhong-quan Mao Ling-yun Tang 聂丹;张弜;邓文基;陈熹;毛忠泉;唐玲云(华南理工大学物理系,广州510640)

机构地区：Department of Physics, South China University of Technology, Guangzhou 510641, China

出　　处：《Chinese Journal of Chemical Physics》2017年第1期97-102,I0002,共7页化学物理学报（英文）

基　　金：The work was supported by the Fundamental Research Funds for the Central Universities, SCUT （No.2014ZZ0069） and the National Natural Science Foundation of China （No.21473211 and No.11304098）.

摘　　要：We have investigated the structure, optical and magnetic properties of ferroelectric KNb1-xFe2O3-δ （x=0, 0.01, 0.03, 0.05, 0.10, 0.15, 0.20, 0.25） synthesized by a traditional solid-state reaction method. According to the X-ray diffraction and the results of Rietveld refinement, all the samples maintain orthorhombic distorted perovskite structures with Amm2 space group without any secondary phase, suggesting the well incorporation of Fe ions into the KNbO3 matrix. With the increase of Fe concentration, the band gap of each sample is decreased gradually, which is much smaller than the 3.18 eV band gap of pure KNbO3. Through X-ray photoelectron spectrum analysis, the increased density of oxygen vacancy and Fe ions may be responsible for the observed decrease in band gap. Compared with the pure KNbO3, Fe doped samples exhibit room-temperature weak ferromagnetism. The ferromagnetism in KNb1-xFexO3-δ with low-concentration dopants （x=0.01-0.10） can be attributed to the bound magnetic polaron mediated exchange. The enhancement of magnetism for the high-concentration （x=0.10-0.20） doped samples may arise from the further increase of magnetic Fe ions.

关 键 词：KNBO3 DOPE Optical property Magnetic property Bound magnetic polaron 

分 类 号：O[理学]