| Indium tin oxide(ITO)is a typical semiconductor material with excellent properties.The thin films made of ITO materials have high transparency and good conductivity,and are commonly used in various fields like flat panel displays,solar cells,gas sensors,functional glasses and so on.ITO mainly has two crystal structures:the cubic crystal phase(c-ITO)and the hexagonal one(h-ITO).C-ITO powder with spherical morphology can be used to prepare high density ITO targets,while h-ITO powder has more excellent properties in some aspects,such as high green density and stable conductivity.In this paper,the single hexagonal phase ITO powders were prepared by binary mixed solvothermal method.Sodium citrate was used as morphology control agent to synthesize the ITO microspheres via the binary mixed solvothermal method.And ITO porous hollow microspheres with cubic crystal phase were obtained using rape pollen template-assisted coprecipitation method.And the influence of the experimental conditions on the micro-morphology,phase structure and resistivity of ITO powders was investigated.The results are as follows:The ITO powders were synthesized by binary mixed solvothermal method.Ammonia was used as the base source.The binary mixed solvent of deionized water and organic solvent was used as the reaction medium.The single hexagonal phase ITO powders were obtained when the binary mixed solvent of deionized water and glycerol(GL)was used as the reaction medium,and their volume ratio was set as 1:1,the reaction was carried out at 200? for 8 h,combining with a subsequent calcination treatment at 400? for 2 h.The ITO powders were composed of small particles of 10?20 nm and some irregular blocks of about 200 nm,which were in good dispersion and the lowest resistivity was 1.258 ?·cm.The ITO powders were prepared by sodium citrate-assisted binary mixed solvothermal method.During this reaction,a mixed solution of deionized water and ethanol was used as the reaction medium and urea as the alkali source.When no additives were added,the obtained ITO powders were small particles of 10?20 nm,and there was obvious agglomeration between powders.When EDTA-Na2 was added,the as-prepared ITO powders were mainly agglomerates made of small particles of 10?20 nm,and some spheres of around 100 nm.When sodium tartrate was added,the morphology of the ITO powders was bulky and microspheres.When sodium citrate was used as an additive,and its addition amount was according to a molar ratio of n(In3+):n(sodium citrate)=1:1,the obtained ITO powders were micron-sized balls with a cubic phase and uniform particle size and they were in good dispersibility.The average particle size was 2.75 ?m and the resistivity was 1.311 ?·cm.The porous hollow spherical ITO powders were synthesized through coprecipitation method assisted with rapeseed pollen as template and sodium citrate as morphology control agent.The powders were micrometer-sized porous hollow spheres with a uniform particle size of about 20 ?m.On the one hand,pollen as a template contains a large number of functional groups on the surface,capable of adsorbing indium tin ions,forming a precursor precipitate wrapped on its surface by adding alkali,and ITO porous hollow microspheres were formed by calcining at 600? for 2 h to remove the template.On the other hand,under the action of sodium citrate,spherical ITO powder was formed.Therefore,the two agents work together to form ITO porous hollow microspheres with a large number of 200?300 nm spheres attached to the surface of the microsphere shell,and the specific surface area was 36.80 m2/g. |
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