乙醇气体的浓度对氧化锌纳米棒气敏元件电学性能的影响

Effect of Ethanol Gas Concentration on Electrical Properties of Gas Sensor Based on ZnO Nanorods

以硝酸锌和氢氧化钠为原料,采用水热合成技术制备了ZnO纳米棒。通过X射线衍射(XRD)、场发射扫描电镜(FESEM)对所合成样品的晶体结构及形貌进行了表征。然后将制备的ZnO纳米粉体压制成气敏元件,研究了气敏元件在空气和不同浓度的乙醇气体中直流电阻、交流电容和阻抗的变化。结果表明,元件在室温(23℃)下从空气转移到20 ppm的乙醇气体中,其直流电阻减小68%。在低频段(<104Hz)的交流电容是随着乙醇浓度的增加而增加,阻抗随乙醇浓度的增大而减小;高频段(104Hz至106Hz)交流电容和阻抗变化很小,基本不受乙醇浓度的影响。当频率为100 Hz时,交流电容和阻抗随乙醇浓度的变化最大,交流电容增大98%,阻抗减小33%。

Zn（NO3）2 and NaOH were used as the raw material to prepare ZnO nanorods through a hydrothermal technique.The crystal quality and morphology of the prepared ZnO nanorods were characterized by X-ray diffraction（XRD） and field emission scanning electron microscope（FESEM）.Gas sensors were made by tabletting the ZnO nanorods and their gas sensitivities were measured.The electrical resistance,capacitance and impedance of the sensor were investigated at room temperature（23 ℃） when exposed to air and ethanol gas of different concentrations.When the sensor was transferred from air to 20 ppm ethanol in air the electrical resistance decreased by 68%.At low frequency（104 Hz）,capacitance increases with the increase in ethanol concentration,while impedance decrease with increase.At high frequency ranging from 104 Hz to 106 Hz,capacitance and impedance changes of the sensor are negligible.A large capacitance and impedance changes can be obtained at 100 Hz,the capacitance increased by 98% and the impedance decreased by 33%.