| 摘要 |
Process for preparing a photographic emulsion containing tabular silver halide grains, which exhibit high speed upon sensitization, having a thickness of about 0.05 to 0.5 mu m, average grain volume of about 0.05 to 1.0 mu m3 and mean aspect ratio of greater than 2:1 comprising A. adding silver nitrate to a vessel containing dispersing medium/bromide mixture, initial bromide ion concentration 0.08 to 0.25 N, to form tabular seed grains; B. adding an ammoniacal base solution, to achieve 0.002 to 0.2 normal of the base (e.g., after at least 2% of total silver nitrate has been added); and C. adding additional silver nitrate and halide, e.g., Br- or BrI-, by balanced double jet procedure. The emulsions are used in photographic elements for x-ray, graphic arts, etc.
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