Preparation of silver halide emulsion to increase sensitivity without affecting crystal habit

摘要

Preparation of a silver halide emulsion of 70-100 mole% silver bromide (AgBr), 0-10 mole-% silver iodide (AgI) and 0-20 mole-% silver chloride (AgCl), in which at least 50% of the projection area consists of tabular crystals with 111 orientation and an aspect ratio at least 2, comprises (a) precipitation of seeds, (b) Ostwald ripening and (c) crystal growth to the final size. The novel features are that (i) seed precipitation is carried out at a pH of 3.5-8 and pBr of 0.5-3.5 and (ii) a strongly acidic, water-soluble organic compound (I) with an average molecular weight of 300-4000 g/mole is added in an amount of 10-10000 mg/mole silver nitrate (AgNO3), before, during or immediately after seed precipitation.