Adsorption of uranium on tungsten single crystal planes

Abstract

Uranium adsorption on the (110), (112), (100), (111), (113) and (116) planes of tungsten field emitter substrates has been studied. Measurements of work function against coverage at 295 K, 950 K and 1120 K were found to be in good agreement with previous contact potential difference and photoelectric measurements. A Topping point dipole depolarization model has been used to determine dipole moments and effective adsorbate polarizabilities. This model is found to be only partially adequate in describing the adsorption process, deviation from the theory being most evident for the (100) plane.

Adsorption of zirconium on tungsten single crystal planes

“…However, the essential features of these plots were reproducible and yielded a certain amount of information. It was found that for measurements on the (100) plane, the work function fell noticeably (about 0.4 eV) in the temperature range 500-1000 K. This is the range in which nucleation is occurring on all planes except the ( 110) and ( 100) (Collins and Blott 1968). The (100) plane appears dark in the emission patterns in this temperature range.…”

“…Recent field emission investigations of the Zr on W system have indicated a number of interesting features in the adsorption and growth mechanisms (Collins and Blott 1968). Adsorption at room temperature has indicated the formation of microcrystallites on specific areas of the emitter and heat treatment of monolayer deposits has resulted in growth apparently by both nucleation and monolayer addition.…”

“…In the present work the probe-hole techniques employed by the authors in the study of uranium on tungsten (Collins and Blott 1971, to be referred to as I) have been employed to study zirconium adsorption on the (110), ( 112), (loo), ( 111) and (310) planes.…”

Silicon adsorption on single-crystal faces of tungsten

“…1 shows a plot of the variation of @with coverage 8 and adatom surface density n for six different single crystal faces. The values used for the work functions of the clean tungsten faces are those used in our previous work [4]. It should be mentioned however, that there is some disagreement regarding the assignment of work functions t o these surfaces, particularly so for the (110) face [8].…”

A study of uranium adsorption to single-crystal tungsten

“…We choose to study uranium adsorption to tungsten for many reasons. First, uranium adsorption to tungsten has been studied both experimentally and theoretically in the past [12][13][14] and this gives us a point of reference. Second, tungsten is used as a working electrode candidate in cyclic voltammetry studies and uranium adsorption to the tungsten electrode has been known to complicate the interpretation of cyclic voltammetry measurements and models.…”