BUCKLED CRYSTALLINE-STRUCTURE OF MIXED IONIC SALTS

X-ray absorption fine structure (XAFS) measurements of mixed salts Rbx K1-xBr and RbBryCl1-y at their congruent melting points compositions r eveal that their actual structure buckles about the NaCl average struc ture with an rms angular deviation from collinearity of 7-degrees-9-de grees. XAFS measures the buckling directly through three-body correlat ions, and verifies the homogeneity and randomness of the mixtures. The characteristic ionic sizes are found to be dependent on concentration , causing changes to 0.1 angstrom in interatom bond distances. A compu ter simulation based on the information from XAFS and diffraction disp lays the actual structure of the salts.