Abstract: In general, the epitaxial silver halide emalsions are prepared under the action of organic crystal growth modifiers. But the organic modifiers have some undersirable effects on the epitaxial emulsions. In this paper, several kinds of epitaxial emulsion were prepared under the action of potassium thiocyanate as a modifier. The etching effect and locality of potassium thiocyanate on the host emulsion grains were studied with the transmitance electron microscopy (TEM). The relationship between etching locality and epitaxial growth position is pointed out. The morphology and crystalline state of octahedral and tabular epitaxial grains were studied. The morphology of the tabular grains with different epitaxial composition were also discribed. Potassium thiocyanate was proved to be an efficient inorganic growth modifier.

Key words: potassium thiocyanate, epitaxial emulsion, modifier, etch, transmitance electron microscopy