真空蒸鍍金汞薄膜及其穿透式電子顯微鏡檢測

Transmission Electron Microscopy of Gold/Mercury Thin Film Evaporated in Vacuum

林彥甫(Yan-Fu Lin)

指導教授 ： 徐統

國立清華大學/工學院/材料科學工程學系/碩士(2009年)

https://doi.org/10.6843/NTHU.2009.00404

摘要

汞和金、銀、銅、鋅等金屬互溶形成各種合金，統稱為汞齊。將微量汞沾附在金片上，可做為液態電極，使奈米碳管與汞接觸形成通路，進行奈米尺度操控及臨場量測，但汞蒸氣可能汙染真空腔並造成真空計讀數不正常。

本實驗以金與汞之間的反應為探討主題，將鍍金燈絲、金線與鍍金鎢線與汞反應形成灰白色汞齊，在不同壓力下對金上的汞通電或加熱，將汞蒸鍍到含有金膜的直徑3毫米銅網上，再使用穿透式電子顯微鏡檢測形貌及分析繞射圖形，以研究在真空中蒸鍍汞之可行性。

電子顯微鏡明場像顯示，汞沒有在金的表面上形成均勻的吸附層，部份金膜與汞反應形成顏色較暗的島狀合金。選區繞射圖形中除了面心立方環，也出現其他斑點。量測繞射環半徑並比較斑點的位置後，判定島狀合金中存在有 Au3Hg 結構，但有少數斑點仍無法鑑定。 Au3Hg 在常壓及真空下皆穩定，故可以金儲存汞做為蒸鍍源，應用於微小尺度及真空中，直接在電子顯微鏡的樣品台上進行蒸鍍。

關鍵字

金 ； 汞 ； 蒸鍍 ； 真空 ； 穿透式電子顯微鏡

並列摘要

Gold, silver, copper and zinc can dissolve in mercury and these alloys are generally called amalgams. Liquid electric contacts by attaching little Hg with gold can establish a closed-circuit between carbon nanotubes and Hg, which is suitable for nano-scale manipulation and in-situ measurement. However, Hg vapor may contaminate vacuum chambers and cause deviation of vacuum gauges.

This study focused on the reaction between Au and Hg. Gray amalgams were prepared by exposing Au wires, filaments and tungsten wires coated with Au to Hg vapor. By charging or heating these wires under different pressures, Hg vapor were evaporated and then deposited on the Au films mounted on 3 mm TEM grids. After the evaporation, the morphology and diffraction pattern of grids were examined under transmission electron microscope in order to study the feasibility of Hg evaporation in vacuum.

Under TEM images, it was found that Hg didn’t form a uniform adsorption layer on Au surface. Some portions of Au film reacted with Hg and became dark island-shaped alloys. In addition to the FCC rings, there are some other spots in diffraction patterns. Au3Hg structures in island-shaped alloys were identified by comparing the radii of different rings and the positions of spots, with few spots unidentifiable. Since Au3Hg is stable at 1 atm and in vacuum, Au can be the storage and the evaporation source of Hg, which would be applied to TEM sample holder to conduct micro-scale evaporation directly.

參考文獻

[4] D. R. Lide, CRC Handbook of Chemistry and Physics, 2008.

[7] J. Simon, S. Saffer, C. J. Kim, J. Microelectromech. Syst. 1997, 6, 208.

[8] P. Sen, C. J. Kim, IEEE Trans. Ind. Electron. 2009, 56, 1314.

[11] C. Guminski, J. Mater. Sci. 1989, 24, 3285.

[12] L. J. Norrby, J. Chem. Educ. 1991, 68, 110.