PHOTOTHERMOGRAPHIC ELEMENT WITH PRE-FORMED IRIDIUM-DOPED SILVER HALIDE GRAINS

摘要

A negative-acting photothermographic element comprising a support bearing at least one heat-developable, photosensitive, image-forming photothermographic emulsion layer comprising: (a) an iridium doped, preferably iridium-doped core-shell, photosensitive silver halide grains, generally containing a total silver iodide content of less than 10 mole %, the shell having a second silver iodide content lower than the silver iodide content of the core; (b) a non-photosensitive, reducible source of silver; (c) a reducing agent for the non-photosensitive, reducible source of silver; (d) a binder; and (e) optionally at least one compound selected from the group consisting of: a halogen molecule; an organic haloamide; and hydrobromic acid salts of nitrogen-containing heterocyclic compounds which are further associated with a pair of bromine atoms. A process of forming photothermographic emulsions from iridium-doped silver halide grains by forming silver soaps in the presence of those grains is also described.