鈦金屬奈米線的合成及其性質

Abstract

在此研究中，我們利用化學氣相沉積的方法讓四氯化鈦與鈦金屬在高溫石英管中反應，反應過後產生的亞氯化鈦經由自身裂解所產生的奈米鈦金屬的反應合成鈦金屬奈米線，並討論可能的反應機制。一開始我們將反應溫度設為1173 K，而此時的反應產物主要為鈦金屬的薄膜，經由反應時間的不同，薄膜的厚度可隨之產生變化。當反應溫度在973K – 1073K附近，鈦金屬的形貌會急遽的變化成一維的奈米結構。所以我們可以在1073 K附近得到鈦金屬的奈米線。此鈦奈米線的直徑約為二十到五十奈米，長度可以到好幾微米。這樣的鈦奈米線已經經由穿透式電子顯微鏡以及X光繞射儀鑑定其形貌、結構與成長方式以及電子場發射性質。同時，我們也利用了電化學的方式將此鈦金屬奈米線的表面積以及電阻量測出來。並測量出表面積與電荷的轉換數值為 900mC / cm2.由這個數值可得到，鈦金屬線的表面積可以到幾何表面積的十五倍。 以上的結果顯示，鈦金屬奈米線未來不管在場發射或是其他應用都有相當大的潛力。

In this research, we demonstrated a simple reaction of TiCl4 and Ti metal that could make pure Ti metal, by self-cracking, deposit on commercial graphite substrate and needless to worry about the non-titanium byproduct appeared in this reaction. At 1173K, the major product of TiCl4 and Ti metal was Ti thin film, the thickness varying from reaction time. When the reaction temperature was controlled at 973 K - 1073 K, the morphology of Ti metal would change dramatically to one-dimensional nanostructures. The diameters of Ti NWs were 20 - 50 nm and the lengths were several hundred micrometers. The growth direction of nanowires was determined to be along the [002] axis of face-centered-cubic structure. Field emission properties, turn-on field Eo, of the vertically grown NWs was determined to be 3.00 Vμm-1. Their corresponding field enhancement factors (□) were calculated to be 1172. By impedance analysis, we could know the electrical resistance was low. By cyclic voltammetry, we measured the value of Ti surface area and charge to be 90 mC / cm2 meanwhile the real surface area of as-grown Ti NWs were 15 times the original geometric area. The results suggested that the Ti NWs could be promising material for further applications.