Silver halide photographic emulsion

Abstract

A photographic silver halide emulsion comprising silver chlorobromide grains containing at least 80 mol % silver chloride or silver chloride grains is disclosed, wherein tabular grains having a thickness of less than 0.5 (my)m, a diameter of at least 0.5 (my)m and an aspect ratio of at least 2/1 account for at least 50% of the total projected area of the silver halide grains, and the tabular grains are formed in the presence of a compound of metal belonging to Group VIII of the Periodic Table. The high silver chloride content emulsion has a sensitivity as high as that of a silver iodobromide emulsion.

What is claimed is: 
     
       1. A photographic silver halide emulsion comprising silver chorobromide grains containing at least 98.5 mol % silver chloride or silver chloride grains, wherein tabular grains having a thickness of less than 0.5 μm, a diameter of at least 0.5 μm and an aspect ratio of at least 2/1 account for at least 50% of the total projected area of the silver halide grains, and said tabular grains are formed in the presence of a compound of a metal belonging to Group VIII of the Periodic Table selected from the group consisting of iron, ruthenium and osmium. 
     
     
       2. A photographic silver halide emulsion as in claim 1, wherein the compound of a metal belonging to Group VIII of the Periodic Table is present in an amount of from 1×10 -8  to 1×10 -2  mol per mol of silver halide contained in the emulsion. 
     
     
       3. A photographic silver halide emulsion as in claim 1, wherein the tabular grains have an aspect ratio of from 3/1 to 8/1. 
     
     
       4. A photographic silver halide emulsion as in claim 1, wherein the tabular grains have a diameter of from 0.7 to 4 μm. 
     
     
       5. A photographic silver halide emulsion as in claim 1, wherein the tabular grains have a thickness of less than 0.3 μm. 
     
     
       6. A photographic silver halide emulsion as in claim 1, wherein the tabular grains account for at least 70% of the total projected area of the silver halide grains. 
     
     
       7. A photographic silver halide emulsion as in claim 1, wherein the silver chlorobromide grains contain at least 99% mol % silver chloride. 
     
     
       8. A photographic silver halide emulsion as in claim 1, wherein said tabular grains comprise a localized silver bromide phase near the surface of the grains. 
     
     
       9. A light-sensitive silver halide photographic material comprising a support having thereon at least one hydrophilic colloid layer, at least one layer of which is a light-sensitive silver halide emulsion layer comprising silver chlorobromide grains containing at least 98.5 mol % silver chloride or silver chloride grains, wherein tabular grains having a thickness of less than 0.5 μm, a diameter of at least 0.5 μm and an aspect ratio of at least 2/1 account for at least 50% of the total projected area of the silver halide grains, and said tabular grains are formed in the presence of a compound of a metal belonging to Group VIII of the Periodic Table selected from the group consisting of iron, ruthenium and osmium.