摘要
利用超薄切片技术(ultramicrotomy)制作铝阳极化成箔之横截面切片,于穿透式电子显微镜(TEM)下对氧化铝介电皮膜厚度,型态,成份与微结构进行观察与分析,并探讨其与皮膜电化学特性表现之关联性.于85℃己二酸铵水溶液中进行铝阳极化成处理.当电压低于100V时,所成长之介电层为非晶质氧化铝皮膜,其电阻值随化成电压升高而增加,但介电常数不受化成电压之影响.当化成电压超过100V时,结晶状的γ′_Al2O3开始出现,且其产生的量随电压值的提高而不断增加,结晶化的过程造成皮膜中缺陷与裂缝产生,以致皮膜电阻逐渐降低,但平均介电常数却有明显随皮膜中γ′_Al2O3增加而升高的趋势.化成电压达到200V时,介电皮膜之结构明显可分为两层,包括内层非晶质氧化铝与外层结晶性γ′_Al2O3;其电化学交流阻抗行为亦显示界面双电容组件特性,结晶性γ′_Al2O3层的电阻较低,但比非晶质氧化铝层具较高电容值.
The thickness, morphology, chemical composition, and crystallinity of the anodized film formed on aluminum were examined in a transmission electron microscope (TEM). Thin foil for TEM analysis was prepared by ultramicrotomy. The relationship between the microstructure and the electrochemical characteristics of the alumina film forming on the pure aluminum was discussed in this investigation. At the forming voltage less than 100V, the anodized films formed at 85 ℃in aqueous ammonium adipate electrolyte was amorphous in nature. Although the film resistance was increased with the forming voltage, its dielectric constant was not changed significantly. As the forming voltage exceeded 100V, crystalline γ′_Al2O3 was present in the film. The amount of crystalline γ′_Al2O3 and the flaws accompanied with the crystallization process were found to increase with the forming voltage. The crystalline alumina seemed to be beneficial in raising the dielectric constant of the oxide film. As the forming voltage reached 200V, the oxide film was composed of an inner amorphous layer and an outer crystalline γ′_Al2O3 layer. The crystalline layer had a lower resistance but a higher dielectric constant than the amorphous layer.
出处
《电化学》
CAS
CSCD
2003年第2期139-146,共8页
Journal of Electrochemistry