烧结温度及掺杂TiO_2对ZnO气敏性能的影响

Calcination Temperature and Adding TiO_2 on Influence of ZnO Gas Sensitivity

通过溶胶-凝胶法制备ZnO凝胶,在300℃预烧结。为了得到不同尺寸的ZnO粉体,并对ZnO粉体进一步纯化,将预烧粉体在不同温度,500℃、700℃、900℃下缓慢烧结,最后将所得粉体涂附在陶瓷管上,在450℃下烧结制备成气敏元件。测试所得的气敏元件对丙酮、乙醇、甲苯这些VOC气体的灵敏性。实验结果表明,500℃下烧结的粉体所作成的器件,对气体具有最大的灵敏度,其原因为随着烧结温度的增加,ZnO的颗粒变大,从而限制了固体与气体的反应面积。再以TiO2材料为掺杂剂,研究掺杂后元件的气敏特性。乙醇和甲苯的最佳工作电流得到了降低,这一现象,将有助于降低器件的工作温度,这也是目前研究ZnO气体传感器主要需要解决的问题。

Transparent ZnO gel was prepared by sol-gel process for getting fine powder of ZnO with the pre-firing at 300 ℃. In order to purify the final products and obtain different grain size, ZnO powder was further calcined at different temperature of 500 ℃ ,700 ℃ and 900 ℃. The sensor was prepared by coating the powder on alumina tubes and post-firing at 450℃ ,then the sensing properties to the volatile organic compound （ VOC ） gases such as ethanol, toluene and acetone were tested. The optimum sensing properties were observed for the specimen calcined at 500℃, and it degraded with the increase in calcination temperature because of the larger grain size that limits the surface area for gas-solid reaction. This paper researched a highly sensitive ZnO-TiO2 based thick film VOC sensor. TiO2 was adding in gas sensor as a dopant. The compound oxide sensor debased the optimum working currents of ethanol and toluene. This phenomenon redounds to debase the sensor working temperature which is the most important problem to ZnO gas sensor.