Physical Defects in Silver Halides

The concentrations of imperfections in silver halides grown from the melt were investigated by comparing the measured densities with the ideal densities computed from the lattice dimensions. The density defect of the most perfect specimen of silver bromide was $\frac{\Delta \rho }{\rho }=-0.8\mathrm{}\times {10}^{-4\mathrm{}}$. The greatest amount of imperfection was $\frac{\Delta \rho }{\rho }=-18\mathrm{}\times {10}^{-4\mathrm{}}$ in a specimen of silver bromide containing about 4 mole percent silver iodide. Considering the effects of various configurations of voids, it seems reasonable to attribute most of the density defect in the best crystals to immobile aggregates of vacancies and to dislocations associated with small-angle mosaic structure. The contributions of large-angle grain boundaries and Schottky defects are negligible.