Transport Studies of Defect Structure Inorganic Compounds
Abstract
Pressure-temperature scans with oxygen on porous silver, as well as the onset of the homonuclear exchange O16(sub 2) and O18(sub 2) ->2 O16-O18, show that the chemisorption becomes reversible at about 160 degrees C. Measurements of the exchange rate were carried out at 160 degrees - 180 degrees C, followed by fast removal of the gas phase and determination of the desorption rate and of the isotopic composition of the desorbing gas. It is thus shown in two independent ways that the desorption rate is equal to the rate of exchange. The chemisorbed oxygen exists in two binding states, but no evidence is found that one of these is in undissociated form. Increase in the proportion of the firmly bound form reduces the desorption rate but causes no change in the activation energy of desorption which is 32.5 kcal/mole 02. The results show that while rapid diffusion and exchange takes place over the entire outer surface, desorption occurs only from those regions which are free of the firmly bound oxygen.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 1965
- Accession Number
- AD0464733