鈦酸鉀奈米線及氮氧化鈦奈米管之合成

Abstract

在本篇論文中，我們合成出鈦酸鉀奈米線，並進一步以奈米線為輔助，成功生長出單晶之氮氧化鈦奈米管，而此種氮氧化鈦一維結構在目前文獻中仍尚未發表。 我們以鈦粉為起始物，與KF及水氣在常壓下合成出鹼硬錳礦(hollandite)與隧狀結構(tunnel structure)混相之鈦酸鉀奈米線，隨著反應時間拉長或起始鈦鉀莫耳比增加，可得到隧狀結構比例較高的產物。調控至最佳反應條件時，我們可得到純相之K3Ti8O17奈米線，其屬於隧狀結構，直徑約100-150 nm，長度可達數十微米，並具有單晶結構，其生長方向為[010]。我們進一步以此鈦酸鉀奈米線做為起始物，NH3為氮來源進行熱處理，成功得到氮氧化鈦之奈米管，外徑介於200-250 nm，內徑約100-150 nm，與奈米線之直徑接近，生長方向為[010]，奈米管為TiN單晶結構，N/O比值約為1.5。我們推測此奈米管的成長機制為具活性之N與奈米線表面及內部反應速率的差異，造成奈米線表面及內部產生晶粒大小的差別，經由類Ostwald ripening機制，最後使得形貌變為管狀。本實驗室生長出之鈦酸鉀奈米線及氮氧化鈦奈米管具有一維且單晶之結構，奈米管並具有粗糙表面，而奈米線亦可生長於基材上，使其未來在光催化、場發射等應用上極具潛力。

Tunnel-structured and hollandite potassium titanates were synthesized by direct oxidation of titanium powders mixed with KF in water vapor. The reaction conditions were adjusted so that long and uniform tunnel-structured potassium titanate nanowires, several tens of micrometer in length and 100-150 nm in diameter, were the major product. The nanowires were single crystalline and the growth direction was determined to be along the [010] axis. The reaction mechanism is investigated and discussed. The nanowires were further treated with NH3 gas at high temperatures to form 1-D titanium oxynitrides nanotubes. The nanotubes were with rough surfaces, about 150-250 nm in outer diameter and 100-150 nm in inner diameter and with a N/O ratio of 1.5. The nanotubes were TiN-structured single crystalline solids. The growth direction was determined to be along the [010] axis. We also proposed a mechanism for the growth of titanium oxynitride nanotubes. The titanium oxynitride nanotubes are found and investigated the first time.