覆銠、銥於鎢針上產生的皺化行為及其相關研究

Abstract

覆銠、銥於鎢針上產生的皺化行為及其相關研究 摘要： 在覆銠、銥於鎢針的皺化行為中，我們以場離子顯微鏡探究其成長模式，發現此兩種系統皆能產生兩種類型的單原子針尖，分別為類型一的1.3.10…結構及類型二的1.6.15…結構。藉由多次重複成長，統計兩種結構的出現機率分佈，可發現覆銠鎢針的系統中1.3.10與1.6.15結構的活化能差ΔEa=0.08eV、束縛位的能量差值ΔEb=0.064eV；覆銥鎢針的系統中1.3.10與1.6.15結構的活化能差ΔEa=0.05eV、束縛位的能量差值ΔEb=0.14eV。 此外，在覆銥鎢針的系統實驗中，我們於退火溫度1029K時可觀察到雙金字塔的現象，經由逐層場蒸發及硬球模型對照可推知在體心立方結構的{221}面上亦有另一金字塔的產生。 最後，合比較覆鈀、鉑、銠、銥鎢針所成長的單原子針尖所具有的共同現象，及分析其間的差異性，以供不同使用的需求做最適當的運用。The faceting structures and related issues on Rh and Ir covered W tips Abstract The faceting structures of Rh and Ir covered W tips are observed by field ion microscope. Two kinds of the single atom pyramidal tips are found for both of the Rh and Ir covered W tips. One we named type I , which the top three layers are constituted with 1, 3, and 10 atoms. The other we named type II , which constituted with 1, 6, and 15 atoms for the top three layers. To get the energy state of two kinds pyramidal tips, the appearance probability distribution are counted by repeated observing and annealing. The difference of activation barriers and binding energy of these two types are determined to be 0.08eV and 0.064eV for Rh covered single atom tip, and 0.05eV and 0.14eV for Ir covered single atom tip. Additionally, we found the double pyramidal structure on Ir covered W tip at 1029K. This new pyramid is sited on W{221} facet. Finally, we conclude the common phenomenon for Pd, Pt, Rh and Ir covered W single atom pyramidal tips and compare their different characters to provide users’ proper choice for different purposes.