Preparation of TeO2Thin Film by Nonhydrolytic Solgel Method and Its Polymerization Mechanism

Abstract:

TeO2 thin films were prepared by nonhydrolytic solgel method with tellurium 1,2propylene diglycollate and tellurium tetrachloride as raw materials,respectively.The nonhydrolytic solgel polymerization mechanism and the microstructure transformation process of the gel films during calcining were studied.The results show that tellurium 1,2propylene diglycollate can form chainlike polymeric molecules,and the nonhydrolytic condensation reaction proceeds between the associated molecular clusters through ether elimination.When tellurium tetrachloride was used as raw materials,the intermediate products tellurium chloride ethoxide were firstly generated by the partly substitution reaction of TeCl4 and C2H5OH.And then the nonhydrolytic condensation reaction took place between these intermediate products via alkyl chloride elimination.The results show that metallic Te formed by different way in the gel films during the films are annealed,which is relative to the amount and position of residual organic component in the gel thin films.When the gel thin films prepared through alkyl chloride elimination nonhydrolytic solgel process,there are more nonbridging oxygen and the crystal of Te2O5 in the films,which is attributing to the residual chloride ion in the network structure of gel thin films.With the increasing of annealing temperature,metallic Te and Te2O5 were reoxidised and decomposed into TeO2,respectively,and the crystal ofβTeO2 and α TeO2 sequentially formed in the thin films.