Study on Electronic Ceramic Materials Synthesized by Sol-Gel Method

1. 将组成金属离子的硝酸盐溶解在乙二醇中，用溶胶-凝胶法制备铁基氧化物粉末。(1)磁铁矿（γ - fe_2o_3）粉体的合成温度低于300 ^ C。(2)在磁铁矿中加入硼、磷或钠均能有效改善磁铁矿的热稳定性和磁性能。粒径小于10nm的超细磁铁矿具有较大的磁矩。在硼浓度B/(Fe+B)=0.2时加入硼得到。(3)采用凝胶法和雾热解法合成了晶体化单相钇铁石榴石（YIG）和铋取代的YIG粉末。柠檬酸盐凝胶处理增加了铋取代量。平底凝胶涂覆制备铁基氧化物薄膜。(1)在B/(Fe +B)=0.2的Fe-B- o体系中，获得了磁化强度为4piM_2 =3.1kG的透明薄膜。(2)在玻璃基板上采用自旋涂覆法制备了更多的YIG和双取代YIG薄膜。用部分铝代替铁，得到垂直磁化膜。磁光法拉第旋转在多涂层薄膜中增强，可能是由于凝胶涂层形成的界面的多重反射。(3)在单晶（GdCa）_3(GaMgZn)_5O_<12>衬底上，在580 ^ C的温度下，采用凝胶包覆法制备了单晶YIG和双取代YIG薄膜。认为晶体生长是由低温液相外延进行的。在配方单元中，铋的取代量大大增加，达到2.5。(4)在玻璃板上采用凝胶镀膜的方法制备了Bi_2O_3-Fe_2O_3-PbTiO_3体系的非晶态铁磁氧化膜，发现该体系薄膜在室温以上同时具有铁磁性和铁电性。凝胶膜的磁性能与溅射膜相似。调查正在进行中。由铁磁微粒组成的磁光材料的研制。研究了分散在液体中的铁磁微粒构成的离散结构mo介质。我们试探性地使用钡铁氧体磁性油墨，磁铁矿和钴悬浮液磁性流体作为磁性颗粒，聚乙烯醇和苯乙烯单体作为树脂。通过在树脂固化过程中施加磁场，可以制备出具有磁性和光学单轴各向异性的透明材料。这些材料的mo特性正在研究中。少

1. Preparation of iron-based-oxide powders by sol-gel method using nitrates of constituent metal ions dissolved in ethylene glycol.(1) Maghemite (gamma-Fe_2O_3) powders are synthesized at temperatures below 300 ^ﾟC.(2) Addition of boron, phosphor or sodium in maghemite is effective for improvement in thermal stability as well as magnetic properties of maghemite. Ultrafine maghemite particles with the grain diameter less than 10nm retaining large magnetic moment. are obtained by the addition of boron at the borronnocentration B/(Fe+B)=0.2.(3) Crystallographic single phase yttrium iron garnet (YIG) and bismuth substituted YIG powders are synthesized by gel processing and mist-pyrolysis. The amount of bismuth substitution is increased by citrate gel processing.2. Preparation of iron-based-oxide thin films by gel-coating on flat substrates.(1) Transparent films with a considerably large magnetization of 4piM_2 =3.1kG were obtained for the Fe-B-O system with B/(Fe +B)=0.2.(2) Polycrystallin … More e YIG and Bi-substituted YIG films were prepared by spin-coating the gel on glass substrates. Perpendicularly magnetized films were obtained by substituting partly aluminum for iron. Magneto-optical Faraday rotation is enhanced in multicoated films by presumably multireflection of interfaces formed by the gel-coating.(3) Single crystal YIG and Bi-substituted YIG films were grown by gel-coating on single crystal (GdCa)_3(GaMgZn)_5O_<12> substrates at a temperature of 580 ^ﾟC. It is considered that crystal growth proceeds from low temperature liquid phase epitaxy. The amount of bismuth substitution is greatly increased up to 2.5 in the formula unit.(4) Amorphous ferromagnetic oxide films with the Bi_2O_3-Fe_2O_3-PbTiO_3 system were prepared by gel-coating on glass plates, since this system films prepared by rf-reactive sputtering are found to exhibit ferromagnetism and ferroelectricity simultaneously well above room temperature. The magnetic properties of gel-coated films resemble those of sputtered films. Investigation is now progressing.3. Development of magneto-optical (MO-) materials composed of fine ferromagnetic particles. MO-media with discrete structure utilizing fine ferromagnetic particles dispersed in a liquid were investigated. We tentatively used magnetic inks of Ba-ferrite, magnetic fluids of magnetite and cobalt suspensions for magnetic particles, and polyvinyl alcohol and styrene monomer for resins. Transparent materials which exhibit magnetic as well as optical uniaxial anisotropies can be prepared by applying a magnetic field during solidification of the resin. MO-properties of these materials are now in progress. Less