氧化物表面单层改性对SnO_2 超微粒子热稳定性的影响(英文)

Effects of Surface Monolayer Modification by Oxides on the Thermal Stability of Tin Dioxide Ultrafine Powder

研究了氧化物在气敏材料二氧化锡超细粉表面的分散行为及分散是对二氧化锡热稳定性的影响．结果表明，氧化铜、氧化锌、氧化铋和氧化锌在二氧化锡表面均能单层分散；分散阈值均与按密置单层模型计算的最大分散客量相符，负载二氧锡的表面覆盖度与其热稳定性之间有很好的对应关系；单层覆盖率达到一定程度二氧化锡高温烧结便可基本得到抑制．

The gas sensors based on SnO2 have always been in an attractive position in the field of study and application of gas sensors. The relevant researches are focused on the improvement or its sensitivity, stability and selectivity([1]). The effects or surface modification by many oxides on the crystallite size and sensitivity of SnO2 have been investigated by Xu et al([3]), and their main results can be summarized as the following: (1) The sintering of SnO2 ultrafine powder can C e retarded by surface modification to a certain extent. (2) When the SnO2 crystallite size is controlled to be not more than firm, sensitivity for H-2 and CO increases steeply with decrease in its size. However, up to now there have not been any systematic and detailed reports in publication about the dispersion behavior of oxides on the surface of SnO2 and the effects of their dispersion amounts ion microstructure and properties of SnO2 after sintered at high temperature. In this paper, the utmost dispersion capacities of CuO, NiO, Bi2O3 and ZnO have been measured, and the effects of their loading on the thermal stability on SnO2 ultrafine powder have been studied. It is observed that all of these oxides can disperse onto the surface of SnO2 as monolayer, and their dispersion thresholds are all in good agreement with their utmost dispersion, capacities estimated from a close-packed monolayer model([3]). It is found that the thermal stability of SnO2 ultraline powder depends on the surface coverage of the oxides on SnO2, and the sintering of SnO2 grain can effectively retarded when the monolayer coverage of the oxides are high enough.