An X‐ray Study of KBr x I 1− x Mixed Crystals

KBr x I 1− x mixed crystals have been prepared by melting and their X‐ray patterns have been recorded with a powder diffractometer. From measurements of the Bragg reflections, the lattice constants, grain size, lattice straian and mean Deby‐Waller factor have been determined. In the composition region × < 0.2 and × > 0.7, the lattice constant follows Vegard's law. However, in the region 0.2 < × < 0.7 where a miscibility gap has been reported, single phase mixed crystals are formed but the lattice constants have values larger than those expected from Vegard's law, indicating a strained lattice. The lattice strain directly determined from the half‐widths of the Bragg reflections also shows larger values in the same composition region. The mean Debye‐Waller factor shows a decrease with the degree of mixing, assuming a minimum value in the equimolar region.