X-RAY-DIFFRACTION STUDIES OF RBBR-RBI MIXED-CRYSTALS

Mixed crystals of RbBr and RbI have been prepared from melt. Using an X-ray diffractometer powder patterns have been recorded. The lattice c onstants show slightly positive deviations from Vegard's law. From the integrated intensities, the mean Debye-Waller factor has been determi ned. The Debye-Waller factor shows a highly non-linear composition dep endence with positive deviations from linearity, the values for interm ediate compositions exceeding those for the end members. The Debye tem peratures calculated from the Debye-Waller factors show a non-linear c omposition dependence with negative deviations from linearity.