ELECTRON OPTICAL STUDY OF TUNGSTEN TRIOXIDE.

Experimental high-resolution electon microscope images of tungsten trioxide have been obtained at 500 kv and 1. 8 A effective resolution. Requirements for obtaining interpretable images of WO//3 at such resolutions are examined, using computer simulations. Images of defects which extend through the specimen along the projection axis, are shown to be directly interpretable and tungsten atom columns can be located to high accuracy (approx. 1/10 of an interatomic spacing), for specimens less than equivalent to 60 A thick, assuming that crystal orientation, incident illumination alignment and appropriate focusing conditions are used.