Study On Gas Sensing Properties Of Doped Nano-iron Oxide Based On Sol-gel Method

With the continuous development of industry, industrial emission of hydrogen sulfide gas is badly harmful to people's lives. Therefore, it is detect particularly important to detect hydrogen sulfide gas, in this way, gas sensor playes a vital role. The research and development of gas sensitivity material has been concerned about by people in recent years.It has an important practical significance to develop a kind of gas sensitivity material for hydrogen sulfide with high selectivity,high stability,high sensitivity and low cost.In this thesis,the gas sensitivity material to detect hydrogen sulfide gas is ?-Fe₂O₃ films.Firstly,undoped sol and 2.5at.%,3.5at.%,4.5at.% Ni-doped sol by sol-gel are prepared and spined them on the interdigital electrodes respectively,which are made by microelectronics technology,After high temperature annealing,gas sensitive element made by different ?-Fe₂O₃ films materials are gained and tested.After analyzing the gas sensing properties of undoped films and different Ni-doped?-Fe₂O₃ films, it is conclude that the optimum operating temperature of different Ni-?-Fe₂O₃ film was about 300?,and the optimum operating temperature of undoped?-Fe₂O₃ film is about 325?. Besides,the sensitivity of 3.5at.% Ni-?-Fe₂O₃ films with different concentration of hydrogen sulfide gas is higher than others, since ?-Fe₂O₃ films have high selectivity to hydrogen sulfide gas due to doped Ni,which indicates that the sensitivity of some other reducing gas is not high,and faster response and recovery speeds of the 3.5at.% Ni-?-Fe₂O₃ films are 8s and 12 s,In addition,it has good stability and repeatability. Through test analysis of gas sensing,sol-gel of Ni doping ?-Fe₂O₃ film has good gas sensitive properties for hydrogen sulfide gas.