Abstract: A Series of multistructure tabular iodobromide micocrystals with the same content and the different distributions of iodide ions were prepared by double-jet precipitation. The relations between structures and sensitivities of multistructure tabular microcrystals were studied,. It is disadvantageous to the improbvement of sensitivity of tabular multistructure microcrytstals, when the iodide-enriched layer is located at the edge of microcrystal. When there is a AgBr core at the center of multistructure tabular microcrystal, the sensitivity of the grains is lowered apparently with the increasing of the core area. The sensitivity of tabular grains with a larger AgBr core is always lower than that of tabular grains with the same iodide ions content but uniformly iodide distributed. When the AgBr core is very small at the center of tabular microcrystal, The sensitivity will be higher, but unfortunately, with the concentrating of iodide to the center of microcrystal, it will be more difficult to prepare tabular grains with high aspect ratio and narrow grain size distribution.

Key words: multistructure tabular microcrystal, sensitivity