Investigations On Synthesis,Characterization And Electrothermal Properties Of Tin Dioxide Based Thin Films

Functional transparent conductive films is becoming more and more important in daily life.Four kinds of tin dioxide-based thin films were designed.The electrothermal properties of the samples were tested by XRD,FT-IR,FE-SEM,HR-TEM,four-probe tester and thermal power tester.The phase,morphology,structure and properties of the samples were characterized,and the electrothermal properties of the materials were discussed in depth.The details are as follows:?1?Transparent conducting Sb doped SnO₂?ATO?films was deposited on glass substrate by ultrasonic spary method.Precursor solution was prepared by Sol-gel method using SnCl₄·5H₂O and SbCl₃ as sources for tin and antimony,anhydrous ethand as solvents.ATO thin films was characterized by X-ray diffractometer,scanning electron microscope,four-point-probe setup and electric heating experiments.Results indicates that ATO films can be made greatly by ultrasonic spary method and has a tetregonal SnO₂ phase.Crystallinity of the films increases by increasing the substrate temperature.Minium sheet resistance of ATO films deposited at 500?,with antimony concentration of 1.5 at%,Sn fixed at 0.6 mol·L-1 is 105?·?^-1,a maxium temperatuer of ?213? is stably maintained over alternating voltage on 220V.?2?Transparent conducting binary doped SnO₂ thin films were deposited on glass substrate by ultrasonic spary method.Precursor solution was prepared by sol-gel method using SnCl₄·5H₂O,SbCl₃,Ni?CH₃COO?₂·4H₂O and La?NO₃?₃·5H₂O as sources,anhydrous ethand as solvents.The results show that binary doping can increase the block resistance of the films,and different doping elements can affect the grain growth of the films.When the content of Ni doping is 3 at%,the infrared emissivity of the films is 0.782,and the maximum heating temperature is 235?.The micro-characterization shows that the surface of the films is smooth.The grain size measured by TEM agrees with that calculated by XRD.When La is doped,the square resistance increases,the infrared emissivity of the films does not change significantly,the heating temperature of the films decreases,and the electrothermal performance becomes worse.?3?The precursor solution of antimony doped tin oxide?ATO?thin films was prepared by sol-gel method using SnCl₄·5H₂O and SbCl₃ as raw materials and anhydrous ethanol as solvent.Then modified carbon nanotubes?CNTs?were added to the precursor solution to form stable precursor suspension.CNTs/ATO composite films were deposited on clean quartz glass by ultrasonic spray pyrolysis method.The results show that CNTs/ATO composite films can be successfully prepared by ultrasonic spray pyrolysis.The composite films still remained the SnO₂ tetragonal rutile structure.After modification,CNTs were dispersed evenly in the ATO precursor solution and the prepared films were more uniform than films prepared with unmodified CNTs.The lowest square resistance of modified CNTs/ATO films reached32?·?^-1 and the highest heating temperature reached 362?at dry temperature unde r220 V.?4?Because of the aging phenomenon of ATO thin films and the limited infrared emissivity,the idea of "double-layer films" is proposed,so we prepare a layer of high infrared emissivity on the surface of ATO thin films to alleviate the aging phenomenon of electrothermal thin films and improve the infrared emissivity.The experimental results show that the conductivity of the double-layer electrothermal films has not been reduced,but the heating temperature has been improved.Compared with ATO films,the infrared emissivity has risen to more than 0.85,and the thermal properties of the films have not decreased significantly after many times of electrification.