Silver chlorobromide emulsions and processes for their preparati

Radiation imagery chemistry: process – composition – or product th – Post imaging processing – Developing

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430567, 430569, G03C 102, G03C 524

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active

044143060

ABSTRACT:
Tabular grain silver halide emulsions are disclosed containing chloride and bromide in at least annular grain regions. The tabular grains having a thickness of less than 0.5 micron, preferably less than 0.3 micron, a diameter of at least 0.6 micron, and an average aspect ratio of at least 5:1, account for at least 35 percent of the total projected area of the total silver halide grain population. The average molar ratio of chloride to bromide in at least the annular grain regions ranges up to 2:3. The tabular grains containing chloride and bromide in at least annular grain regions are formed by maintaining a molar ratio of chloride and bromide ions of from 1.6:1 to 258:1 and the total concentration of halide ions in the reaction vessel in the range of from 0.10 to 0.90 N during introduction of silver, chloride, and bromide salts into a reaction vessel, thereby favoring the coprecipitation of chloride and bromide in a tabular crystal habit.

REFERENCES:
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patent: 4067739 (1978-01-01), Lewis
patent: 4150994 (1979-04-01), Maternaghan
patent: 4184877 (1980-01-01), Maternaghan
patent: 4184878 (1980-01-01), Maternaghan
Claes et al., "Crystal Habit Modification of AgCl by Impurities Determining Solvation", The Journal of Photographic Science, vol. 21, pp. 39-50, 1973.
Wyrsch, "Sulfur Sensitization of Monosized Silver Chloride Emulsions with (111), (110), and (100) Crystal Habit", Paper III-13, International Congress of Photographic Science, pp. 122-124, 1978.
deCugnac and Chateau, "Evolution of the Morphology of Silver Bromide Crystals During Physical Ripening", Science et Industries Photographiques, vol. 33, No. 2, (1962), pp. 121-125.
Duffin, Photographic Emulsion Chemistry, Focal Press, 1966, pp. 66-72.
Trivelli and Smith, "The Effect of Silver Iodide Upon the Structure of Bromo-Iodide Precipitation Series", The Photographic Journal, vol. LXXX, Jul. 1940, pp. 285-288.
Gutoff, "Nucleation and Growth Rates During the Precipitation of Silver Halide Photographic Emulsions", Photographic Sciences and Engineering, vol. 14, No. 4, Jul.-Aug. 1970, pp. 248-257.

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