气敏半导体材料Cd_2Sb_2O_(6.8)的制备及其性能研究

Studies on Preparation and Properties of the Gas sensing Semiconducting Material Cd 2Sb 2O 6.8

采用化学共沉淀法，在较低温度（７５０℃）下制备了具有缺陷烧绿石结构的复合氧化物Ｃｄ２Ｓｂ２Ｏ６．８的纯相超微粉；研究了制备条件对物相、结构和气敏性能的影响，并对其反应过程机理进行了探讨．气敏性能测试结果表明，纯相Ｃｄ２Ｓｂ２Ｏ６．８气敏元件对乙炔气体有较高的灵敏度和较好的选择性．

A chemical coprecipitation method is developed to have successfully prepared the ultramicro powder of Cd 2Sb 2O 6.8 pure phase with a defect pyrochlore structure. The effects of the coprecipitation conditions and calcining temperature on the phase compositions and structure are studied. The result shows that the pure Cd 2Sb 2O 6.8 phase can be only obtained when n (Cd)/ n (Sb) molar ratio is kept as around 0.90, while other ratios ( i.e. 0.85 and 1.00) lead to impure phases. The minimum calcining temperature for the pure phase formation is 750 ℃, which is lower than that for other methods reported in literature. A formation procedure mechanism of the Cd 2Sb 2O 6.8 phase is proposed in terms of high temperature ionic diffusion reaction: Cd ions diffuse into a kind of dehydrated antimony acid which possesses a defect pyrochlore structure, react and gradually form the ultramicro power of Cd 2Sb 2O 6.8 . The gas sensing properties of the thick film gas sensor elements made of this pure Cd 2Sb 2O 6.8 powder are tested. Compared with the elements made of the powders by conventional solid state reaction method, the elements from this wet chemically prepared ultramicro powders show much improved gas sensing properties. The sensitivity to 1.0×10 -4 C 2H 2 is even higher than that to 3.0×10 -3 H 2 or CO as well as 1.0×10 -3 C 2H 4. The high sensitivity and good selectivity to C 2H 2 demonstrate it a promising acetylene gas sensing material .