Controlled Fabrication Of TiO₂-based Antimony Doped Tin Oxide Composite And Its Electrical Conductivity

Development and application on the preparation process of multifunctional conductive titanium dioxide?TiO₂?have great potential application value in the conductive and antistatic field.In this paper,TiO₂-based antimony doped tin oxide?ATO?conductive composite were effectively prepared by three different methods.Furthermore,the microstructure of the composite conductive material can be gradually regulated by controlling the slow release of the cations and anions needed for crystallizatio of conductive components.The microstructure,phase structure and material composition of the obtained composite were characterized by SEM,TEM,XRD,EDS,XPS,FTIR and so on.The relationship among the main preparation conditions,microstructure and the conductivity of the as-prepared composite materials was mainly investigated.And the reaction mechanism of different preparation methods was discussed.The conductive mechanism models of TiO₂–based conductive composite were initially established.1)With ammonium persulfate as initiator,tin and antimony metal chloride,butyl titanate and acrylic acid solution were mixed and copolymerized to form polymer precursor.The product was pyrolyzed to form TiO₂/ATO composite powder with good crystallinity.The solid–solid interfacial synergism effect between anatase-and rutile-type phases and the?staggered?type double heterojunction at the interface of the mixed-phase TiO₂/ATO were formed,which promotes the electrons migrating from TiO₂?A?to TiO₂?R?and then ATO in a cascadal way along the potential gradient.When the molar ratio of Ti to Sn is 5:1 with 8.3%Sb being doped into SnO₂,TiO₂/ATO sample has the narrowest equivalent energy gap of 2.79eV,and it has enhanced conductivity with a resistivity of 15.42?·cm.2)Core-shell conductive composite powders of TiO₂ coated with ATO nanoparticles were prepared with urea as the precipitant by homogeneous precipitation.When the molar ratio of metal cation to urea for precipitation reaction is 1:10 at the temperature of 92?,the release amount and rate of OH^?are moderate.At the same time,the sulfates were introduced as the catalyst to reduce the nucleation barrier of metal cations,in which the optimum molar ratio of O₄² to Cl^?is 1:25.Uniform,continuous and compact shell layer of ATO of the obtained product is formed on the surface of the TiO₂ with a thickness of approximately 15 nm.When completely covered,the resistivity of composite powders decreases first and then,when the molar ratio of Sn to Sb reaches 12:1,changes little with the increase of Sb doping amount.The resistivity value reaches 3.98?·cm.3)TiO₂@ATO composite conductive materials were prepared by tartaric acid-assisted homogeneous precipitation method to complex with metal cations.Effects of precipitant and complexing agent on the conductivity of composite powder were mainly investigated.ATO particles with the size of about 12.3 nm are coated on the surface of near–spherical rutile TiO₂,forming a core–shell composite structure,and all constituent elements are evenly distributed in the composite.In this reaction system,tartaric acid provides the intermediate with ligands,and urea regulates the pH of the system.Under the same optimum experimental conditions as the homogeneous precipitation,when the molar ratio of TA to Sb reaches 1:1 and that of urea to Sn is 5:1,the as-prepared TiO₂@ATO has the optimal conductivity and its resistivity is 3.25?·cm.