【作者】 周小燕；

【导师】 李强；

【作者基本信息】 武汉理工大学 ， 材料学， 2002， 硕士

【摘要】 掺铈钇铁石榴石（Ce-substituted Yttrium Iron Garnets，简称Ce：YIG）中，由于Ce³⁺离子对Y³⁺离子的取代，将大大提高钇铁石榴石（Yttrium Iron Garnets，简称YIG）磁光材料的法拉第旋转角和磁光优值，使其能够广泛应用于激光和光通信等高技术领域。然而受Ce³⁺离子半径较大，Ce³⁺离子易被氧化成Ce⁴⁺离子等因素的影响，Ce：YIG的合成中Ce³⁺离子的掺杂变得异常困难。本文在充分分析本领域国内外研究现状的基础上，采用化学合成法制得单相YIG和Ce：YIG，并对其组分、结构特征和磁性能进行了分析研究。 采用共沉淀法合成YIG及Ce：YIG前驱体，通过提高组分均匀性、降低煅烧温度等手段，有效地抑制了YFeO₃杂相的生成和Ce³⁺离子的氧化，合成了单相YIG和Ce：YIG。研究表明，共沉淀的过程和条件控制对YIG的合成具有重要影响。实验得出共沉淀的合适条件为：以NH₃-NH₄NO₃为缓冲溶液，控制PH范围为10.0—10.5，采用可溶性盐为原料配制溶液，滴加到沉淀剂中的共沉淀方式，共沉淀速度为0.8ml／min左右。XRD分析表明：当配料为化学计量比（即Y／Fe的摩尔比为3：5），在900℃及其以上的煅烧温度下，可以得到立方结构的单相YIG：Ce的掺量在合适的范围内(以Ce_xY_3-xFe₅O₁2计，X≤0.2)，在900℃的煅烧温度下，可以制得纯相的Ce：YIG，当提高煅烧温度或增大Ce掺量时，都会有CeO₂的析出。利用SEM技术观察、分析、讨论了共沉淀法合成的YIG和Ce：YIG颗粒之间团聚、颗粒尺寸及分布情况。 结合YIG组分特点，建立了快速、准确的YIG和Ce：YIG化学分析法——络合置换滴定和氧化还原滴定法，有效地实行了对Fe³⁺、Y³⁺的连续滴定，并分别测定了Ce⁴⁺和Ce³⁺的含量。化学分析结果与EDS分析相一致。XPS的分析结果显示单相Ce：YIG（X≤0.2时）中Ce离子是以正三价的状态存在，这与物相分析结果是一致的。 VSM测试结果表明YIG属于亚铁磁性物质， Ce离子的掺杂对饱和磁化强度（Ms）、剩余磁化强度（Mr）、矫顽力（Hc）都有一定的影响。 YIG和Ce：YIG的合成及其成分、结构和性能的分析，为Ce：YIG单晶的制备和研究奠定了良好的基础。更多还原

【Abstract】 Cerium-substituted yttrium iron garnets (CexY3-xFe5O12, Ce :YIG), the promising materials for magneto-optical(MO) application, have been widely attended for great improvement on Faraday rotation due to the substitution of Ce3+ ions to Y3+ ions. However, studies on synthesis of Ce:YIG were restrained by two factors: the first was radium of Ce3+ ions were much larger than that of Y3+ ions, the second was Ce3+ ions tended to transfer to Ce4+ ions which were more chemically stable. In this paper, YIG and Ce:YIG were prepared via chemical synthesis method, and their composition, structure, magnetic properties were investigated.YIG and Ce:YIG precursors were prepared via coprecipitation. By means of improving homogeneity and decreasing synthesis temperature, harmful YFeO3 phase was restrained, the oxidation of Ce3+ was under control, and pure phase YIG and Ce:YIG(x=0.2) were obtained. Studies showed that process and condition control had critical effect on the preparation of YIG phase, and the proper conditions specialized as follows: using ammonia-ammonium nitrate(NH3-NH4NO3) as precipitant, PH scope from 10 to 10.5, using dissolving salt as law materials, dropping their mixed solution into precipitant, precipitation rate at 0.8ml/min. The results of X-ray powder diffraction(XRD) indicated that cubic YIG pure phase could be acquired at the synthesis temperature of 900 with stoichiometric proportion. While the doping content was not more than 0.2, Ce:YIG pure phase could be prepared at the synthesis temperature of 900. As doping content of cerium or synthesis temperature increased , CeO2 phase segregated.The constituent analysis method was developed by means of complexometric titration and oxidation reduction titration. The composition of Fe3+ and Y3+ ions were analyzed continuously and the composition of Ce3+ and Ce4+ ions was determined respectively. The results of chemical analysis were consistent with that of energy dispersion spectrophy (EDS). The results of X-ray photoelectron spectrum (XPS) demonstrated the Ce ions in pure phase Ce:YIG(x< 0.2) were in the state of trivalence.Scanning electron microscope (SEM) analysis showed conglobation of YIG and Ce:YIG particles, whose size were smaller than 1 urn. Vibrating samples magnetometer (VSM) testing implied that YIG were of ferrimagnetism, and Cerium substitution had effects on saturation magnetization(Ms), residual magnetization (Mr) and coercive force(Hc).The investigation of synthesis, composition and structure analysis, and characterization of magnetic properties of YIG and Ce:YIG would build foundation for the study of Ce:YIG single crystal in the future.更多还原