均匀沉淀法制备核-壳型TiO2@SbxSn1-xO2及其导电性能

Preparation and electrical conductivity of TiO2@SbxSn1-xO2 core-shell composite particles by homogeneous precipitation

以尿素为沉淀剂,采用均匀沉淀法包覆改性TiO2,制备了核壳型TiO2@SbxSn1-xO2(ATO)复合导电粉体,利用SEM、EDS、HRTEM、XRD、XPS、顺磁波谱仪(EPR)、FTIR及激光粒度仪(LPSA)等对其进行表征,并对其导电性的主要影响条件进行了研究及分析,提出了均匀沉淀包覆及反应机制。研究表明,反应温度为92℃时,尿素与金属阳离子摩尔比为10∶1的情况下,OH-释放量及释放速率适中,引入SO24-作为催化剂,降低金属阳离子成核能垒,且SO24-与Cl-最佳摩尔比为1∶25时,所得产品的纳米SbxSn1-xO2(ATO)壳层在TiO2表面包覆均匀连续完整,其厚度约为15nm。当包覆完全时,随着Sb掺杂量增加,复合粉体电阻率降低,Sn与Sb摩尔比达到12∶1时,再增加Sb含量,其电阻率不变。最优制备条件下,复合粉体电阻率值为7.5Ω·cm,导电性能良好。

Core shell conductive composite powders of TiO2 coated with SbxSn1-xO2 antimony-doped tin oxide(ATO)nanoparticles were prepared with urea as the precipitant by homogeneous precipitation.The as-prepared composite powders were characterized by SEM,EDS,HRTEM,XRD,XPS,electron paramagnetic resonance(EPR),FTIR and laser particle size analyzer(LPSA),respectively.Effects of several main experimental parameters on the resistivity of the TiO2@ATO powders were primarily investigated.A possible mechanism for coating of ATO nanoparticles on the surface of TiO2 microspheres was proposed.The results show that when the molar ratio of met-al cation to urea for precipitation reaction is 1∶10at the temperature of 92℃,the release amount and rate of OH-are moderate.At the same time,SO4^2-was introduced as a catalyst to reduce the nucleation barrier of metal cations,in which the optimum molar ratio of SO4^2-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 15nm.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.Under the optimum experimental conditions,TiO2@ATO has good electrical conductivity with the resistivity of 7.5Ω·cm.