Abstract: A AgBrI emulsion was prepared by pAg-controlled double jet methods.Reductionsensitization was performed by silver digestion at low pAg values and high pH values(D₀>5.0),them more AgBr was precipitated on to the digested emulsion by the same double-jet procedure at defferent pH values(pH 2,4,6,8).The influence of the method of preparation on the structure and the properties of AgX microcrystals was studied in the PaPer.It was shown that with pH changes during shell-formation grain size increase,thecrystal shape was transformed from regular octahedal to rouned octahedral,and thedensity by surface development and the ionic conductivity increase but density by internal development decrease.At the same pH,the density by surface development was downrapidly with the change of the core-shell ratio of 1:0.5,1:1,1:2,1:3.

Key words: internally fogged emulsion, preparation conditions, photographic properties, ionic conductivity