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Cheap metal salts and ethanol as raw material , the sol - gel dip-coating method ( sol-gel dip -coating method , SGDC ) Preparation of Gas Sensitivity polycrystalline thin films . This paper explores the preparation process of the film , determined by XRD, SEM analysis, and testing of the electrical properties of the film , the film preparation process parameters : copper , antimony and tin chloride ethanol solution by mixing heated 5 hours later, the organic solvent was evaporated , and 0.57 mol / L , to control the concentration of Sn2 . And then the resultant solution and glycerine mixed volume of 12:1 , and configured to obtain a coating solution . The substrate was immersed in the coating solution for 30 seconds after the vertical Ti Laji sheet flat. After the wet film hydrolysis after some time in the air and then at 100 ~ 120 ℃ dried for 15 minutes . Repeat coating of a total of five times, and then heat - treated for 120 minutes at 600 ℃ . The doping amount of Sb ??and Cu are determined by experiment . Sb-doped amount of 5 at% , the resistance of the film is the smallest, approximately 70 K ? ; Cu doped amount of 1 at% , the gas sensing properties of the film is preferably : at 250 ℃ of high concentration (137 ppm) and low concentrations (13.7 ppm) of H2S gas sensing has a good effect size sensitivity of 18.3 and 2.7 , respectively . Of Cu : Sb : Sn 1:5:100 film gas sensitive properties tested . Working temperature of 140 ° C , the film sensitivity to H2S H2S concentration of 13.7 ppm sensitivity 10 ; film sensitive to the concentration limit of up to 0.7 ppm , corresponding to the sensitivity of 3 ; better recovery characteristics of the response of the films : 250 ℃, the response time of the film is about 8 s, the recovery time is about 40 s ; 140 ° C , the response time is about 1.3 s , the recovery time of about 530 s . XRD and SEM analysis showed that the films are polycrystalline thin films of SnO2 nanocrystals , the average grain size of approximately 30 nm .
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