Crystallochemical studies in the family of crystals Ba[7-x]Na[y]F₁₂Cl[2-z]Br[z] (x < 0.1, y < 0.2, z < 1.5)

A series of mixed crystals with general formula Ba7-xNayF12Cl2-zBrz in the ordered modification (space group P-6) has been studied by single crystal x-ray diffraction. Depending on synthesis conditions, the disorder in the channels (i.e. occupation of 0 0 z sites) can be changed. The disorder is found to be correlated with the refined Na content, and its effect on Ba-Cl(Br) bond length is discussed