Core/shell silver donors for photothermographic systems comprising an oxidatively less reactive shell

A color photothermographic element having on a support at least tree light-sensitive color imaging layers which have their individual sensitivities in different wavelength regions, each of said imaging layers comprising a light-sensitive silver emulsion, a binder, a dye-providing coupler, and a developer or developer precursor, the dyes formed from the dye-providing couplers in the layers being different in hue, therefore capable of forming at least three dye images of different visible or non-visible colors,

• wherein at least one imaging layer comprises particles of non-light-sensitive organic silver salts, the particles comprising a first organic silver salt and a second organic silver salt,
• wherein greater than 50 mole percent of the first organic silver salt in the particle overlies greater than 50 mole percent of the second organic silver salt in the particle, and
• wherein said first organic silver salt and said second organic silver are different, and wherein the pKsp of said first organic silver salt is at least 0.5 higher than the pKsp of said second organic silver salt.

A black-and-white or monochrome photothermographic element having on a support at least one light-sensitive imaging layer comprising a light-sensitive silver emulsion, a binder, and a developer or developer precursors,

• wherein the imaging layer comprises core/shell particles of non-light-sensitive organic silver salts, the particles comprising (i) an outside shell comprising at least one organic silver salt, and (ii) under the outside shell, an underlying particle that comprises a core comprising at least one organic silver salt and, optionally, one or more intermediate shells each comprising at least one organic silver salt, wherein the outside shell is defined as the outside shell that substantially covers the underlying particle;
• said at least one organic silver salt in the outside shell comprising a first organic silver salt and said at least one organic silver salt in the underlying particle comprising a second organic silver salt,
• wherein said first organic silver salt and said second organic silver salt are different and the pKsp of said first organic silver salt is at least 0.5 higher than the pKsp of said second organic silver salt, and the pKsp of both salts are greater than 11.

A black-and-white or monochrome photothermographic element having on a support at least one light-sensitive imaging layer comprising a light-sensitive silver emulsion, a binder, and a developer or precursor thereof,

• wherein at least one imaging layer comprises particles of non-light-sensitive organic silver salts, the particles comprising a first organic silver salt and a second organic silver salt;
• wherein greater than 50 mole percent of the first organic silver salt in the particle overlies greater than 50 mole percent of the second organic silver salt in the particle;
• wherein said first organic silver salt of a first category and said second organic silver salt are different, wherein the pKsp of said first organic silver salt is at least 0.5 higher than the pKsp of said second organic silver salt, and the pKsp of both organic silver salts is greater than 11.