| 摘要 |
A method is disclosed for the preparation of silver halide tabular emulsion grains, containing at least 75 % chloride, wherein at least 50 % of the total projected area of all the grains is provided by said tabular grains, and wherein said tabular grains exhibit an average aspect ratio of at least 5:1, an average thickness not greater than 0.5 micron and an average diameter of at least 0.6 micron, comprising the following steps : preparing a dispersion medium containing a gelatino-peptizer, and a compound (Ia) or compound (Ib), e.g. adenine, in a concentration ranging from 10 <-><4> to 10<-><2> molar, said medium being adjusted to a pH between 5.0 and 9.0 and to a pCl between 1.0 and 2.0 by means of a chloride ions providing salt; performing a silver halide precipitation comprising at least one double jet step by introducing in said dispersion medium at least one solution containing chloride ions and at least one solution containing silver ions in such a way that pCl is maintained between 1.0 and 2.0, pH is maintained between 5.0 an 9.0 and the concentration of compound (Ia) or (Ib) is maintained between 10 <-><4> molar and 10<-><2> molar; removing excess of soluble salts by a wash technique performed at a pH value comprised between 4.0 and 9.0. o
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