Patent ID: 7063941

Claim:
A method of preparing a photothermographic emulsion comprising: (A) providing a photothermographic dispersion of preformed photosensitive silver halide grains and a non-photosensitive source of reducible silver ions, and performing the following steps (B-1) and (B-2) but not step (C) in either order or at the same time, (B-1) providing an organic sulfur-containing compound that is a diphenylphosphine sulfide in association with said preformed photosensitive silver halide grains and said non-photosensitive source of reducible silver ions, (B-2) converting some of the reducible silver ions in said non-photosensitive source of reducible silver ions into in-situ photosensitive silver halide grains, and then (C) chemically sensitizing at least said preformed photosensitive silver halide grains by decomposing said organic sulfur-containing compound on or around said preformed and in-situ photosensitive silver halide grains in an oxidizing environment to provide a photothermographic emulsion comprising sulfur chemically sensitized preformed and in-situ photosensitive silver halide grains in reactive association with said non-photosensitive source of reducible silver ions.