Three AgCl/AgBr(I) cubic emulsion grains were prepared successfully by
epitaxial deposition of AgCl on (111) surfaces of three cubo-octahedr
al AgBr(I) host grains made at various pAg values by a microcomputer-c
ontrolled, balanced, double-jet method. Using powder X-ray diffractome
try, the component phases of these epitaxial emulsion grains were iden
tified, corresponding to the host AgBr(I) phase and a new AgCl phase,
respectively. The dielectric loss curves of epitaxial grains showed tw
o separated peaks, corresponding to the contribution of the AgBr(I) ho
st phase and epitaxial AgCl to ionic conductivity, respectively. The p
hotoconductivity decay process for both host and epitaxial grains was
composed of slower and faster parts, each of which obeys first-order k
inetics. The epitaxial procedure modified effectively the amount and m
ean lifetime of photoelectrons. The photosensitivities of epitaxial em
ulsions were much higher than those of the host emulsions, which can b
e attributed to the epitaxial growth benefiting the formation of conce
ntrated latent image.