Abstract: It was found that the AgBr grain size increased with the increasing concentration of l,7,10,16-tetraoxa-4,13-dithia-cyclooctadencan (2S-18-C-6) in the emulsion due to the latter’s complexation with Ag⁺, and subsequently the decrease of the supersaturation of the AgBr nucleation, and the photochemistry and dielectric loss of the prepared AgBr emulsion changed with the grain size in a regular pattern.The addition of the crown ether to the deionized bone-gelatin solution made small crystals dissolved, thus, well-distributed emulsion with high contrast could be got.Emulsion ripening was quite concerned with the heteroatoms in the crown ethers,2S -18 - C - 6 could act as a strong physical ripener while l,7,10,16-tetraoxa-4,13-diazacyclooctadecan (2N-18-C-6)and N-toluensulfonyl -7-aza-l,4,10,13-tetrathiacyclohexadecan (NTsTTH) could only act as the solvents of AgBr, and 1,4,7,10,13,16-hexaoxacyclooctadecan (18-C-6) has merely ripening effect on the emulsion.

Key words: AgBr emulsion, crown ether, supersaturation, physical ripening