本篇研究為透過柯爾磁光顯微儀觀察氫氣在鈷鈀合金薄膜中的移動情形，及磁域的變化。樣品皆在超高真空系統下（〖10〗^(-8)torr）利用熱蒸鍍原理將鈷和鈀兩種金屬對鍍形成合金，對鍍完成後，使用柯爾磁光顯微鏡量測氫氣吸附前後的磁光特性改變，以及表面磁域的變化，並分析不同時間下氫氣的擴散情況。鈀在吸附氫氣後會變成氫化鈀，隨著時間的增加，氫氣的吸收量也愈來愈多，可由柯爾顯微儀所量測之磁滯曲線看出氫氣在鈷鈀合金內的擴散情形，藉由殘磁率的變化了解氫氣濃度的擴散及變化。樣品固定Pd的鍍量且Pd的比例為75%，較高比例的Pd有助於觀察氫氣可逆反應之現象。當Co25Pd75的薄膜中的氫氣-金屬之原子比率由0%上升至5%，磁滯曲線的殘磁率亦由20%上升至100%，氫氣在CoPd薄膜中吸收與擴散速率遵守Fick’s擴散定率，擴散係數為3±2×〖10〗^(-12) m^2/s。當氫濃度為2%、3%及4%時的擴散前沿移動速率在缺陷處最快可達50±20nm/s，而在均勻的薄膜的區域則降為30±15nm/s。在氫氣的脫附過程中，合金薄膜中氫含量的橫向擴散速度在30±15nm/s間調節，這些實驗結果證明氫氣在不透明的鈀合金薄膜中，擴散現象是可被觀察的，這些皆可能在未來被應用在氫氣靈敏感測或氫氣儲存系統中。

In this study, we measure hydrogen movement in Co25Pd75 alloy film by magneto-optical Kerr effect microscope. The samples are prepared in an ultra-high vacuum system (UHV) by co-evaporation of Cobalt and Palladium, which form an alloy film. After sample preparation, we use Magneto-Optical Kerr effect microscope to monitor the magneto-optical image of sample during hydrogen diffusion.
While palladium adsorbs hydrogen, it becomes hydrogenated palladium. As time goes by, the adsorption amount of palladium on hydrogen atoms increases. The situation of hydrogen movement in CoPd alloy film can be observed by Kerr effect images. According to the change of magnetic remanence, we can know how the hydrogen diffuses in CoPd alloy. It’s relatively easy to observe the phenomenon of hydrogen reversible reaction in high concentration of Pd, so we make the concentration of Pd at 75%.
When hydrogen-metal atomic ratio in Co25Pd75 alloy film raised from 0% to 5%, the residual magnetization rate in the hysteresis loops also raised from 20% to 100%. The velocity of hydrogen diffusion in CoPd alloy film follow Fick’s diffusion law with the diffusion coefficient of 3±2×〖10〗^(-12) 〖 m〗^2/s. The diffusion velocity of 2%, 3%, and 4% hydrogen concentration front are 30±15 nm/s in the area of uniform film and increases to 50±20nm/s near a defect area.
In the process of hydrogen desorption, lateral diffusion speed of hydrogen content in the alloy film could be regulate as 30±15 nm/s. These experimental results prove that hydrogen diffusion can be observed in nontransparent CoPd alloy film. Those can probably be applied in hydrogen-sensing and -storage technology.

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