Preparation And Gas Sensing Property Study Of Al-Sn Co-doped ZnO

Zinc oxide is an important n-type metal oxide semiconductor material with wide forbidden band and direct band gap. and with six-party wurtzite structure, Zn O is the earliest gas sensitive to be used. It has the characteristic of high exciton binding energy, wide bandgap,no toxic and easily available raw materials when compared with other materials. At present, the Zn O gas sensitive materials research hot spot and the focal point lies in:how to enhance the gas-sensing de in properties of Zn O gas sensors.In this topic, pure Zn O and 7wt%, 9wt%, 11wt% Al-doped Zn(OH)2 material were prepared by the chemical co-precipitation method. And when the mass fraction of Al was 9wt%,mixed different amounts of tin(the amount of tin was 1wt%, 3wt%, 5wt%).doped Zn O materials were obtained after annealing process(500℃,700℃,900℃).Crystal structure and surface topography of different doped samples were characterized by. And use the gas sensor test system to test gas sensitive properties of acetone gas sensors. The main research content is as follows:1. The Zn(OH) 2 precipitation is prepared from the Zn(COOH) 2 ·2H2O and Na OH by chemical co-precipitation method. Al(NO3)3·9H2O and Sn Cl4·5H2O as the doping agent.The precursor were obtaind by controlling the concentration of the precursors, stirring speed,PH and other process parameters,and then dying,grinding,cleaning and high tempareture treatment,finally get the samples of different doped Zn O powder.2. The samples were characterized by XRD. The results show that the samples could be indexed to wurtzite Zn O and with the increase of doping amount,crystal size.3. The surface morphology of samples were characterized by SEM. The SEM diagram show that the samples were six prism,the surface of doped samples were porous,and Al-Sn co-doped grain size decrease obviously, which increase the specific surface area and can improve the gas sensing property.4. The different samples were tested by gas test system and analyzed. The results indicate that the highest sensitivity can be achieved by doping the amount of 9wt%Al-3wt%Sn. It has much better sensing performance towards acetone vapor under the working tempreture was 75 ℃and annealing 700℃. The sensitivity is 12590. And can meet the needs of practical of application.