新型掺铈钇铁石榴石磁光薄膜材料

对新型掺铈钇铁石榴石磁光薄膜材料(Ce:YIG)的制备工艺、磁光特性及理论分析进行了较全面的评述,并指出今后研究的方向。     

石榴石型磁光存储材料

稀土铁石榴石薄膜被认为是最具应用前景的下一代磁光记录材料。稀土铁石榴石薄膜具有高的矫顽力、良好的热、化学稳定性及强的磁光效应等特点；特别是当Ｂｉ３＋和Ｃｅ３＋离子部分取代石榴石结构中的稀土离子后，可以极大地增强其磁光效应。本文就磁光记录的原理、磁光存储材料、稀土铁石榴石磁光薄膜的制备及其如何降低石榴石薄膜中的晶界噪声等问题作了一些探讨。     

用于高性能光隔离器的复合稀土铁石榴石ReYbBiIG单晶材料研究

通过加速旋转坩埚技术和Bi₂O₃/B₂O₃助溶剂生长技术研制新型磁光复合稀土铁石榴石单晶ReYbBiIG(Re:Tb³⁺、Ho³⁺、Y³⁺。从理论上解释了将两种具有相反符号法拉第温度和波长系数的掺铋稀土铁石榴石复合可以显著优化磁光性能,并成功制得具有大磁光优值、低饱和磁化强度、低近红外吸收、极小法拉第温度和波长系数的系列优质磁光单晶(如:Ho_0.85Yb_1.12Bi_1.03Fe₅O₁₂和Tb_2.06Yb_0.46Bi_0.48Fe₅O₁₂等)。研究表明,以新型磁光复合稀土铁石榴石单晶ReYbBiIG作为法拉第转子材料制得的新型光隔离器更适用于WDM光纤通讯系统对宽波段和温度稳定性的要求。     

RF溅射沉积Ce：YIG磁光薄膜的热处理结晶化研究

基片温度低于溅射外延条件，采用低溅射功率密度磁控溅射沉积，进行后期热处理结晶晶化，制备出膜厚为３００ｎｍ的掺铈钇铁石榴石Ｃｅ：ＹＩＧ磁光薄膜。对热处理前的的磁光特性进行比较，并分析了热处理结晶化过程中附属相的变化。薄膜在空气中热处理结晶化过程中附属相的变化。薄膜在空气中热处理结晶化温度在６５０℃附近。热处理后，室温上６３３ｎｍ处其法拉第旋转系数约为１．９×１０＾４ｄｅｇ／ｃｍ，光吸收系数为２５００     

YIG薄膜制备方法研究

就工艺，测试结果，性能等方面综述了钇铁石榴石YIG（Yttrium Iron Garnet)薄膜的制备方法，包括Sol-Gel、CVD、溅射、PLD、LPE等。从YIG复合薄膜的制备、基片选择等角度，提出通过提高YIG薄膜制品的磁光性能从而改善磁光器件整体性能的新思路。     

稀土铁石榴石磁光材料及其应用

本文综述了稀土铁石榴石磁光材料及磁光器件研究的最新进展；对最具应用价值的高掺Ｂｉ系列和掺Ｃｅ系列石榴石磁光材料作了介绍，在磁光器件方面选择了最具代表性的磁光隔离器和光纤电渗／磁场测试仪加以讨论。     

掺Ce稀土铁石榴石块状单晶生长及磁光性能研究

掺Ce稀土铁石榴石单晶是目前最具发展前景的新型法拉第旋转材料。与GdBiIG,YIG等材料相比,具有更大法拉第旋转、小的温度系数和低廉成本等特点。本文采用改进的助熔剂法,成功地生长出块状Ce:YIG单晶,分析晶体结构,测试近红外波段磁光性能。Ce3+掺入铁石榴石十二面体位极大地增强了材料的法拉第旋转角,在λ=0.78μm时Y3Fe5O12晶体中每一个Ce3+替代Y3+,其θF的增加量(dθF/dx)达到0.6×104deg/cm,是同量Bi3+替代晶体θF增加量的2倍。另外,在稀土铁石榴石中掺入Yb3+和Eu3+,由于其存在弱的还原性,能抑制ce4+的形成,增加Ce3+离子的掺入量。     

稀土铁石榴石磁光材料及其应用

本文综述了稀土铁石榴石磁光材料及磁光器件研究的最新进展；对最具应用价值的高掺Ｂｉ系列和掺Ｃｅ系列石榴石磁光材料作了介绍；在磁光器件方面选择了最具代表性的磁光隔离器和光纤电流／磁场测试仪加以讨论     

石榴石型磁光存储材料

稀土铁石榴石薄膜被认为是最具应用的前景的下一代磁光记录材料。稀土铁石榴石薄膜具有高的矫顽力，良好的热，化学稳定性及强的磁光效应等特点；特别是当Ｂ＾３＋和Ｃｅ＾３＋离子部分取代石榴石结构中的稀土离子后，可以极大地增强其磁光效应。     

掺铈钇铁石榴石(Ce:YIG)的合成

采用共沉法合成掺铈钇铁石榴石前驱体，并在900℃的温度下，煅烧合成钇铁石榴石相。利用XRD，SEM，XPS对材料的物相，形貌和Ce离子的价态进行了分析。XRD分析表明，Ce：YIG是纯的YIG相；SEM分析表明，试样颗粒呈球状，尺寸小于0.5μm，且有一定程度的团聚；XPS分析表明，Ce：YIG中Ce离子以正三价形式存在。     

掺铋钇铁石榴石磁光陶瓷的热压烧结及其性能研究

钇铁石榴石(Y₃Fe₅O₁₂, YIG)材料因其优异的磁性能和磁光性能在微波通信、激光技术和光纤通讯等领域具有重要应用。离子掺杂是提高YIG材料磁光性能的有效途径之一, 本研究选择离子半径适配的Bi³⁺掺杂改性YIG陶瓷以提高材料的磁光性能。本工作采用固相法热压烧结制备Bi_xY_3-xFe₅O₁₂ (x=0、0.3、0.6、0.9)陶瓷, 并研究Bi³⁺掺杂对YIG陶瓷材料相结构、微观形貌、红外透过性、磁性能以及磁光性能的影响。结果表明: 陶瓷样品均呈石榴石立方相结构; 显微结构致密, Bi³⁺掺杂后晶粒尺寸不同程度增大; 样品红外透过率良好, 随Bi³⁺掺杂量增大而降低; 陶瓷样品的法拉第旋转角随Bi³⁺掺杂量增加呈线性变化, Bi³⁺掺杂量每增加1% (原子分数), 在波长1064 nm和1550 nm处变化量分别约为-49.0 (°)/cm和-30.2 (°)/cm。Bi_0.6Y_2.4Fe₅O₁₂陶瓷样品在1064 nm和1550 nm波长下法拉第旋转角分别达到-703.3 (°)/cm和-461.5 (°)/cm, 绝对值远高于未掺杂YIG陶瓷的277.6 (°)/cm和172.0 (°)/cm。由此可见, 掺杂适量Bi³⁺可以显著增强YIG陶瓷材料的磁光性能。     

Compact one-dimensional magnetophotonic crystals with simultaneous large Faraday rotation and high transmittance

We have investigated the case of transmission-type one-dimensional magnetophotonic crystals (MPCs) in order to achieve simultaneous high transmittance and large Faraday rotation utilizing few magnetic layers. In a MPC that includes two Ce:YIG magnetic layers, we have achieved a Faraday rotation as large as 85.82° and a transmittance of 95.66%. In addition, another structure in the form of a triple-cavity MPC with a transmittance of 100% and a Faraday rotation as huge as 87.72° has been achieved through precise selection of layer thicknesses and positions. Both of these high-performance structures are very compact and thin, which makes them excellent candidates for application in integrated MO devices.     

BST/YIG复合材料的相结构、介电性能和磁性能的研究

以铁电性的钛酸锶钡（BST）和铁磁性钇铁氧体（YIG）为原料,采用固相反应法,合成了一系列铁电/铁磁复合材料,并对铁电/铁磁复合材料（YIG/BST）的介电性能和磁性能进行了详细地研究. 结果表明：在一定温度下烧结所得的铁电/铁磁复合材料,由铁电相和铁磁相两相组成;xBST-(1-x)YIG(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.0)复合材料具有良好的介电性能和磁性能, 其介电常数实部ε′与虚部ε″均随BST含量的增加而升高,且介电常数的谐振峰随着YIG含量的增加而向频率高的方向移动.磁导率实部μ′与虚部μ″均随BST含量的增加而降低. 在YIG铁氧体中加入适量的陶瓷BST构成复合材料,可以有效地改善截止频率,提高高频电磁特性.     

新一代磁光材料及器件研究进展

磁光材料是典型的多功能材料,其应用频率覆盖了射频、微波、毫米波、THz波和光波段,是一类优秀的全波段材料.首先对磁光材料发展的动态进行了分析;其次就磁光材料应用于磁光盘、光纤通信器件、THz器件等进行了讨论;最后,对作者课题组的一些新的研究工作做了介绍,以期能对这一领域的发展起到促进作用.     

Magnetically tunable oscillators and filters

Magnetically tunable filters and oscillators can be built throughout the 500-MHz-110-GHz range using a number of ferrite materials and varied geometries. The authors survey current trends and state-of-the-art results for oscillators and filters using YIG spheres _, YIG films, and hexagonal ferrites as the magnetically tunable elements     

1998～1999年国际磁性功能材料新进展

本文为从1981年开始的关于国际磁性功能材料新进展的每年综述的继续,这里介绍了1998－1999年间若干磁性功能材料的新进展,包括（1）Fe-Ni系氮化物磁性材料;（2）巨磁电阻抗材料;（3）YIG系微波铁氧体;（4）稀土巨磁致伸缩材料;（5）纳米磁性材料。     

Effect of deposition temperature on the properties of sputtered YIG films grown on quartz

Yttrium Iron Garnet (YIG), Y₃Fe₅O₁₂, is an oxide material that has potential applications in the magneto-optical recording media and microwave device industries. These materials, when synthesized in thin film form, usually require post-deposition annealing in order to enhance their physical properties. Furthermore, integration of YIG based optical components requires the synthesis of high quality YIG material on quartz, a process that may be problematic due to poor adhesion and lattice mismatch. Thus, we have conducted a study on the effect of deposition temperature (from 25 to 800 °C) and post-deposition annealing (at 740 °C) on the crystalline quality and chemical composition of YIG thin films, grown by radio-frequency magnetron sputtering, on quartz substrates. X-ray diffraction (XRD) shows that as-grown layers are amorphous, and subsequent annealing is necessary to induce film crystallization. Rutherford backscattering spectrometry analyses were also conducted and the chemical composition of the films was found to depend on initial deposition temperature and is affected by post-deposition anneals. Comparison of the XRD and RBS results point out to the existence of an optimal deposition temperature at about 700 °C for the formation of high crystalline quality and stoichiometric YIG thin films. Magnetic measurements were found to correlate to the XRD and RBS analyses.     

Low-temperature synthesis and microstructure-property study of single-phase yttrium iron garnet (YIG) nanocrystals via a rapid chemical coprecipitation

Single-phase yttrium iron garnet (Y₃Fe₅O₁₂, YIG) nanocrystals have been synthesized via a rapid chemical coprecipitation process with reverse strike operations, followed by calcining the precipitates at the temperature around 750 °C. The formation of YIG nanocrystals from the amorphous precipitates and their microstructural features and magnetic properties were investigated by FT-IR, XRD, TG-DSC, FESEM, TEM and VSM. It has been found that the as-obtained precipitates could be thermally activated to directly form the crystalline phases of garnet structure around 650 °C, including cubic YIG and minor tetragonal YIG but no trace of YFeO₃, which was often involved during the synthesis of YIG or doped-YIG when a chemical coprecipitation method was used. The calcinations could make the tetragonal YIG entirely transform into the cubic phase at 750 °C and allow the crystallites of the latter to grow from ∼22 nm to ∼50 nm in size almost linearly as a function of the temperature ranging from 650 °C to 900 °C. Moreover, the room temperature saturation magnetization of the samples after calcinations at various temperatures showed a nonlinear increase from 0.24 emu g⁻¹ to 24.54 emu g⁻¹, which should be associated with the alignments of atomic magnetic moments in the materials from completely-disordered to partially-ordered firstly and further to completely-ordered and, in the last stage, mainly with the growing YIG nanocrystals.     

The magnetic and dielectric properties of microwave sintered yttrium iron garnet (YIG)

Yttrium iron garnet (YIG) material is widely used in microwave devices. Experiments show that microwave sintering (MS) treated YIG materials possess excellent properties with a saturation magnetization of 14.60 emu/g and coercive force 34.82 Oe. In the frequency range of 1 MHz–1.8 GHz, the relative dielectric constant is from 6.5 to 7.0, the line-width is 105 Oe, dielectric loss less than 0.09 and magnetic loss less than 0.7. Furthermore, the sintering time and temperature were significantly reduced from 20 h and 1300 °C for the conventional sintering (CS) process to 2 h and 900 °C for MS technique, respectively.     

YIG rod ferrite limiter with extended dynamic range

Analytical and experimental results obtained on aC-band ferrite limiter which utilizes a YIG rod inserted down the center of a coupled dielectric resonator bandpass structure are described. This device is aimed at providing receiver protection for communication systems operating in a dense, high signal power environment. By utilizing a long thin single-crystal YIG rod instead of YIG spheres, the dynamic range has been extended from 20 dB to 35 dB. The threshold power varies from 5 dBm at 4.4 GHz to 15 dBm at 5 GHz with an insertion loss of less than 1 dB.