Radiographic elements with improved covering power

摘要

Monocyclic and polycyclic azoles having the following formula enhance the covering power of a developed silver image formed from a radiographic element comprising a radiation sensitive tabular grain silver bromide, silver bromochloride or silver bromoiodide emulsion layer containing grains having a mean equivalent circular diameter of at least 0.3 (my)m and a grain population wherein at least 50 percent of the total grain population projected area is accounted for by tabular grains having a tabularity of greater than 8, as determined by the relationship: (* CHEMICAL STRUCTURE *) wherein T is tabularity; ECD is the mean effective circular diameter in (my)m of the tabular grains; and t is the mean thickness in (my)m of the tabular grains. The azoles have the formula: (* CHEMICAL STRUCTURE *) (I) wherein Z is -N= or -C(R5)= where R5 is hydrogen, -NH2, aliphatic of 1 to 8 carbon atoms or aromatic of 1 to 8 carbon atoms; R4 is hydrogen, aliphatic of 1 to 8 carbon atoms or aromatic of 1 to 8 carbon atoms; R4 and R5 together complete a 5 or 6 membered heterocyclic nucleus containing 1 to 3 ring nitrogen atoms; L is a divalent aliphatic linking group containing 1 to 8 carbon atoms; T is an aliphatic terminal group containing 1 to 10 carbon atoms; m is 0 or 1; n is an integer of 0 to 4; and p is an integer of 2 to 4.