Abstract
The effects of negative high-electric fields of the order of 107–108 V/cm on oxidation of tungsten and molybdenum single crystals were investigated at 1200–1500 K for tungsten and at 900–1100 K for molybdenum, respectively, with the aid of a field emission and a transmission electron microscope. Oxidation of field emitters in the presence of a field resulted in the growth of crystallized oxides on the emitter surface, in different manners with tungsten and molybdenum. For tungsten, oxide crystals were constructed selectively on the {110} planes, whereas, for molybdenum, an oxide overlayer with a facetted structure was formed on the entire emitter surface.