Preparation of Metal-Oxide nano-granular thin films with soft magnetic property by wet process

金属氧化物纳米颗粒膜是由纳米级磁性金属颗粒嵌套在氧化物基体中形成的，具有软磁性能和高电阻。因此，这些薄膜作为高频微磁器件的材料受到了广泛的关注。金属氧化物纳米颗粒薄膜通常是通过溅射制备的。在CoSO_4和Ce(NO_3)_3或CeCl_3的反应溶液中，采用“金属氧化物共电沉积”的电化学方法制备了Co-Ce-0薄膜。然而，这些薄膜的最小矫顽力保持在160欧。本课题旨在通过电化学方法制备具有良好软磁性能的金属氧化物纳米颗粒膜。在这个项目中，我们尝试了以下四种方法来获得良好的磁性能：1)用电化学方法制备Fe-Ce-O薄膜。2)电沉积过程中超声波的照射3)利用脉冲波电流进行电沉积4)Co-alloy的电沉积。结果表明：1)在含有FeSO_4、CeCl_3、l-抗坏血酸和（NH_4）_2SO_4的反应溶液中，采用金属氧化物共电沉积方法成功地制备了Fe-Ce-0颗粒膜。l -抗坏血酸具有抗氧化剂的作用，可避免Fe^<2+>被氧化为Fe^<3+>。（NH_4）_2 so_4对Fe^<2+>起络合作用，避免了Fe(OH)_2的析出。50 Oe的Fe-Ce-0膜矫顽力小于Co-Ce-0膜。2)电沉积法制备Co-Pt薄膜。Co含量在24 ~ 57at之间变化。通过控制镀液中Co^<2+>的浓度。沉积薄膜的退火，包括24-50 at。% Co使其晶体结构由面心立方结构（fee）转变为有序的面心四边形L10结构（fct），矫顽力高达约880 kA/m。

Metal-oxide nano-granular film consisting of nanometer-sized magnetic metal particles embedded in an oxide matrix has soft magnetic property and high electrical resistance. Therefore these films have attracted much attention as materials for the micro magnetic devices operated at high frequency. Metal-oxide nano-granular films have typically been fabricated by sputtering. We have demonstrated that Co-Ce-0 films could be fabricated from the reaction solution containing CoSO_4 and Ce(NO_3)_3 or CeCl_3 by the electrochemical method, call as "metal-oxide co-electrodeposition". However minimum coercivity of these films remained 160 Oe. The aim of this project is to be obtained metal-oxide nano-granular films with good soft magnetic properties by electrochemical method. In this project, we tried the following four approaches for obtaining good magnetic properties:1)Fabrication of Fe-Ce-O films by electrochemical method.2)Irradiation of ultrasonic during electrodeposition3)Using the pulse wave current for electrodeposition4)Electrodeposition of Co-alloy.The following results were derived:1)Fe-Ce-0 granular films have been formed successfully by metal-oxide co-electrodeposition from a reaction solution containing FeSO_4, CeCl_3, L-ascorbic acid, and (NH_4)_2SO_4. L-ascorbic acid acts as antioxidant and avoid being oxidized Fe^<2+> to Fe^<3+>. (NH_4)_2 SO^_4 acts as a complexing agent for Fe^<2+> and avoid the precipitation of Fe(OH)_2. Coercivity of Fe-Ce-0 films with 50 Oe is smaller than Co-Ce-0 films.2)Co-Pt film were prepared by electrodeposition. The Co content in the films was varied from 24 to 57 at.% by controlling the concentration of Co^<2+> in a plating bath. Annealing of the as-deposited films including 24-50 at.% Co transformed their crystal structure from the face-centered-cubic structure (fee) to the ordered face-centered-tetragonal L10 structure (fct), and the coercivity up to approximately 880 kA/m was obtained.