X-ray diffraction has been used to study the de equilimixtion in solid state of Rb(BrXIi..) solid solutions The compositions of the phases in equilibrium at room temnerature are 0.18 RbBr-0.82 RbI and 0.96 RbBr-0.04 ÉZb1, respectively. The maximum critical temperature of the demixtion is 422ºC, corresponding to the composition X~t.1= 0.35. AS a result of this experimental work the existente of a single-phase region at high-temperature and a two-phases region at interdifracmediate and low-temperature has been established
