TiO_2基气敏元件工作温度影响机理

Impacting mechanism of operating temperature of TiO_2-based sensor

对TiO2基气敏材料的能带结构及测试气体分子轨道能量进行理论计算,结合实验,对TiO2-SnO2复合材料气敏元件工作温度的影响机理进行理论研究。结果表明:掺杂使TiO2能带带隙中产生掺杂能带,导带产生负移,有利于电子热激发。对比未掺杂TiO2气敏元件,在工作温度为260℃时,掺杂使TiO2元件电阻值由44.5MΩ下降到22.5MΩ。气体分子LUMO能级降低,有利于降低气敏反应的活化能,从而降低气敏元件的工作温度及提高灵敏度。

Theory calculation for band structure of TiO2 - based gas - sensing materials and the orbital energy level of tested gas molecules were carried out. The best operating temperatures of TiO2 - SnO2 gas sensor to some gases were measured experimentally. The results show that there are some new energy bands in the band gap and the conductance band move towards lower energy state. These effects are beneficial to the electron excitated. When the operating temperature at 260℃, the resistance of TiO2 - based gas sensor is 22.5MΩ, while for the non - doped TiO2 gas sensor is 44.5MΩ. When the lowest unoccupied orbital energies （ELUMO） of the tested gas decreased, the operating temperature of gas sensors dropped and the sensitivity increased as the reaction activation energy decreased.