Preparation and Characterization of Transparent Magnetic Oxide Meterials

透明磁性氧化物材料的制备及表征

基本信息

批准号：
06453122
负责人：
SOGA Naohiro
金额：
$ 5.38万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

Transparent magnetic oxide materials are useful as magnetooptical devices and windows for shielding of magnetic fields. The aim of the present research is to prepare new transparent magnetic oxide materials and to characterize the magnetic, optical, and magnetooptical properties of the resultant materials. The main results of the research can be summarized as follows :(1) Faraday effect measurements have been carried out at room temperature for some sodium borate glasses containing Eu^<2+> ions prepared under a reducing atmosphere. The wavelength dependence of the Verdet constant is analyzed in terms of a theory derived by Van Vleck and Hebb to obtain effective transition wavelength of the 4f^7*4f^6 5d transition which canuses the Faraday effect of Eu^<2+> in the visible range. The effective transition wavelength increases with an increase in the optical basicity of glass. This phenomenon is explained in terms of the crystal field theory ; because the splitting of 5d levels is larger i … More n the glass with larger optical basicity, the energy required for the 4f^7*4f^6 5d transition decreases as the optical basicity of glass increases. The magnitude of Verdet constant increases with an increase in the effective transition wavelength when the concentration of EuO remains constant.(2) We have examined the effect of heat treatment temperature and time on the magnetic properties of rapidly quenched oxides with compositions close to ZnFe_2O_4, which show high magnetization even at room temperature as we found. In particular, an attention is focused on the oxide with nominal composition of 60ZnO・40Fe_2O_3. X-ray diffraction, Zn K-edge extended X-ray absorption fine structure (EXAFS), Mossbauer spectroscopy, and magnetization measurements are carried out to clarify the variation of crystal structure and magnetic properties with heat treatment. The rapidly quenched specimen contains zinc ferrite with lattice parameter 0.05% smaller than that of ZnFe_2O_4 as the main phase, and exhibits the magnetization of 23.8 emu/g at room temperature. The X-ray diffraction, EXAFS and Mossbauer measurements suggest that the high magnetization is brought about by the Fe^<3+> ion clusters with the Zn^<2+> ions occupying octahedral sites as well as the solid solution of Fe_3O_4 in the ZnFe_2O_4. As the heat treatment temperature increases, the room temperature magnetization decreases sluggishly below 500ﾟC and decreases sharply above 600ﾟC when the heat treatment time is 2h. The variation of EXAFS and Mossbauer spectra with heat treatment temperature suggests that the decrease of magnetization below 500ﾟC corresponds to the transfer of Zn^<2+> ions from octahedral to tetrahedral sites while the rapid decrease of magnetization above 600ﾟC is caused by the oxidation of Fe^<2+> to form ZnFe_2O_4 with normal spinel structure. A complicated behavior is observed at around 550ﾟC ; the magnetization once increases at 550-600ﾟC and then decreases rapidly as the heat treatment temperature increases. We speculate that at the initial stage of the oxidation of Fe^<2+>, vacancies of Fe^<3+> ions at the octahedral sites are created, leading to the increase of magnetization. Less

透明的磁氧化物材料可用作磁性设备和窗户，用于屏蔽磁场。本研究的目的是准备新的透明磁氧化物材料，并表征所得材料的磁，光学和磁性。研究的主要结果可以概括如下：（1）在室温下对某些含Eu^<2+>离子的钠玻璃杯进行了室温进行测量。 VARDET常数的波长依赖性是根据Van Vleck和Hebb得出的理论来分析的，以获得4F^7*4F^6 5D过渡的有效跃迁波长，该波长在可见范围内conude can can can can can can can can can faraday eu^<2+>。有效的过渡波长随着玻璃的光学碱度的增加而增加。这种现象是用晶体场理论解释的。由于5D水平的分裂更大的I…n更多的具有更大的光学碱度的玻璃，因此随着玻璃的光学碱度的增加，4f^7*4f^6 5D过渡所需的能量会降低。当EUO的浓度保持恒定时，Verdet常数的幅度随有效过渡波长的增加而增加。（2）我们已经检查了热处理温度和时间对快速淬灭氧化物的磁性的影响，其成分接近Znfe_2O_4，接近Znfe_2O_4的组合物在房间温度下也显示出高磁化。特别是，注意力集中在氧化物上，名义成分为60zno ・40FE_2O_3。进行X射线衍射，Zn K边缘扩展X射线抽象细胞（EXAFS），Mossbauer光谱和磁化测量值，以通过热处理阐明晶体结构和磁性特性的变化。快速淬灭的标本包含锌铁氧体，其晶格参数比Znfe_2o_4小0.05％作为主相，并在室温下显示23.8 EMU/g的磁化。 X射线衍射，EXAF和Mossbauer测量表明，高磁化是由Fe^<3+>离子簇带来的，占用八面体位点的Zn^<2+>离子以及Znfe_2O_4中Fe_3O_4的实心解决方案。随着热处理温度的升高，当热处理时间为2H时，室温磁化缓慢降低到500°C以下，并急剧降低至600 c。 EXAFS和Mossbauer光谱随热处理温度的变化表明，磁化的降低低于500°C，对应于Zn^<2+>离子从八面体到四面体位点的转移，而磁化强度的迅速下降到600 c c的速度是由Fe^<2+> znfe znfe znfe snolugation引起的600 c。在约550°C左右观察到复杂的行为；磁化强度在550-600 c时增加，然后随着热处理温度的升高而迅速降低。我们推测，在Fe^<2+>氧化的初始阶段，创建了八面体位点的Fe^<3+>离子的空缺，从而导致磁化的增加。较少的