Abstract: The photographic performances of photothermographic (PTG) materials based on silver benzotriazole (AgBTA) and silver 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (AgTAI) have been studied, in which, hydrophilic polyvinyl alcohol (PVA) is used as a binder and the AgBrI prepared by in-situ method as photo-sensitive element. It is found that the mixed silver source PTG materials have a higher sensitivity than the PTG materials based on single AgBTA. The mechanism of the mixed silver source PTG materials with a higher sensitivity has been investigated according to the measurements of pH, pAg of the emulsion and the differential scanning calorimetry (DSC) of the mixed silver salts. It is analyzed that the elevation of the sensitivity is due to the fine grains of mixed silver salts and high concentration of silver ions so that promote the development process.

Key words: photothermographic material, silver benzotriazole, silver tetraazaindene, photographic performance