LATTICE STRAINS IN DISORDERED MIXED SALTS

X-Ray absorption fine structure measurements, and computer simulations were used to solve the structure of mixed salts RbBrxCl1-x. Deviation s from the average NaCl structure (nearest neighbor distances and buck ling angles) were observed which maximize in the midst of the concentr ation range. This induces a local elastic strain energy which is the c ause of the melting point depression below the linear interpolation. I t is shown for the first time that the concentration-weighted average of the Rb-Br and Rb-CI bond lengths is always greater than the average determined by diffraction. Copyright (C) 1996 Published by Elsevier S cience Ltd.