低温熔盐中电沉积Sm-Co合金膜及其磁性能

Electrodeposited Sm-Co Alloy Films and Their Magnetic Properties in Low Temperature Molten Salts

在353K的尿素-乙酰胺-NaBr-KBr熔体中,用恒电位电解法在Cu基片上制备了Sm-Co合金膜.利用循环伏安法研究了熔体的电化学行为.电化学实验结果表明,在Pt电极上,Co(II)+2e"Co(0)是一步完全的不可逆反应;测得CoCl2-尿素-乙酰胺-NaBr-KBr熔体中,Co(II)在Pt电极上的传递系数!=0.31,扩散系数D0=4.78×10-5cm2·s-1;Sm(III)难以单独沉积,但能被Co(II)诱导共沉积,在不同阴极电位下制备出不同Sm含量的非晶合金膜.用等离子发射光谱仪(ICP)检测薄膜成分,用SEM观察了薄膜的表面形貌结构,用XRD和振动样品磁强计(VSM)分析样品退火前后的晶相和磁性能变化特征.结果表明,在923K进行退火30s后Sm-Co薄膜由非晶转变为多晶结构,并以hcp晶相结构为主;退火和Sm含量对Sm-Co合金膜的磁性能有重要的影响.

Electrodeposited Sm-Co alloy films, obtained on copper substrate in urea-acetamide-NaBr-KBr melt at 353 K, were prepared. The cyclic voltammetry was used to study the electrochemical processes. Electroreduction of Co （Ⅱ） to metallic Co was irreversible in one step, On Pt electrode the diffusion coefficient Do and electron transfer coefficient a of Co（Ⅱ） in CoCl2 （0.040 mol·L^-1-urea-acetamide-NaBr-KBr were determined. Their values were obtained as follows： α=0.31 and D0=4.78×10^-5 cm^2· s^-1. Sm（III） was not reduced to Sm alone, but it could be inductively codeposited with Co （Ⅱ）. The cathode potential had evident effect on the content of Sm in the Sm-Co alloy films. The content of Sm was analyzed by inductive coupled plasma emission spectrometer （ICPES）. The structures phase of the deposits before and after annealing at 923 K for 30 s were investigated by XRD, magnetic properties were measured by vibrating sample measurement （VSM）, and the microstructure was observed by scanning electron micrographs （SEM）. The experimental results revealed that, （1） the prepared samples were amorphous while the annealed those were polycrystalline, and there existed a main hcp phase in annealed polycrystalline samples; （2） the annealing and the samarium content had important influence on magnetic properties of SmxCo5 alloy films.