Ag_2O的添加对PdO吸附量以及微观结构的影响

Influence Ag_2O Addition on Adsorption and Microstructures of PdO Getter Materials

为了从样品的微观结构方面解释各种吸气剂吸附量的大小,利用ASAP2010型物理吸附仪,在77 K下对其进行高纯N2吸附和脱附,再结合BET二常数公式法、MP法和BJH法,分析它们的微观结构和吸附量的变化关系。结果表明:样品的吸附等温线属于第Ⅳ类吸附等温线,它们的孔结构多为中孔。与不含Ag2O的样品相比,Ag2O的添加使样品的孔径分布的最高峰向直径减小的方向发展,添加Ag2O的质量分数wAg2O=15%的样品的比表面积和孔容积分别增大了29.2%和4.8%,使其吸附量增大。与添加wAg2O=15%的样品相比,添加wAg2O=30%样品的比表面积和孔容积分别减小了11.7%和12.6%,且其孔径分布曲线的强度小,使其吸附量减小。Ag2O的添加使样品中的微孔消失,并且其平均孔径随wAg2O的增加而减小。但是样品中含有Ag2O后,wAg2O的增减对其平均孔径的影响不大。

The influence of Ag2O addition on the adsorption and desorption of nitrogen at 77 K, and the variations in the mierostructures of the PdO getter materials was studied. The correlation between the micmstructures and adsorption capacity of the Ag2O-added PdO was analyzed with Brunaner-Emmett-Teller（BET） equation, Mikhail et al（MP） and the Barrett-Joyner-Halenda （BJH） methods and the adsorption-desorption isotherms. The resttlts show that its type Ⅳ isotherm may be accounted for by the meso-pomus structures. The increase in Ag2O addition resulted in a shift of the pore-size distribution （PSD） peak toward smaller pore size, with respect to that of the control sample. The addition of Ag2O （ 15 % （wt） Ag2O） into PdO increased the specific surface area and total pore volume by 29.2% and 4.8 %, respectively, and significantly enhanced its adsorption capacity. However, the specific surface area and total pore volume of the PdO with 30% Ag2O were 11.7% and 12.6% lower,respectively,than those of PdO with 15% Ag2O. Moreover, its adsorption capacity decreased possibly because the micro-pores vanished.