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

由纳米磁性金属颗粒镶嵌在氧化物基质中的金属氧化物纳米颗粒膜具有软磁性能和高电阻。因此，这些薄膜作为高频工作的微磁器件材料引起了人们的广泛关注。金属氧化物纳米颗粒膜通常是通过溅射的方法制备的。我们证明了以CoSO4和Ce(NO3)3或CeCl3反应溶液为原料，采用“金属-氧化物共沉积”的电化学法可以制备Co-Ce-0薄膜。然而，这些薄膜的最小矫顽力仍然是160Oe。本项目的目标是通过电化学方法获得具有良好软磁性能的金属氧化物纳米颗粒膜。在本项目中，我们尝试了以下四种获得良好磁性的方法：1)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)利用脉冲电流进行电沉积；4)电沉积Co合金。结果表明：1)在含有FeSO4、CeCl3、L-抗坏血酸和(NH4)2SO4的反应溶液中，采用金属氧化物共沉积的方法成功地形成了Fe-Ce-O颗粒膜。L-抗坏血酸作为抗坏血酸的抗氧化剂，避免了Fe^&lt；2+和Gt；3+&gt；(NH_4)_2SO_4对Fe~(2+)~(2+)和Gt~(2+)起络合剂作用，避免了Fe(OH)_2的析出。Fe-Ce-0薄膜的矫顽力小于Co-Ce-0薄膜。通过控制镀液中Co~(2+)和Gt~(2+)的浓度，薄膜中的Co含量在24~57at.%之间变化。当Co含量为24-50at.%时，薄膜的晶型由面心立方结构转变为有序的面心四方L10结构，获得了约880kA/m的矫顽力。

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.