Neutron diffraction study of the solid solutions Ksub(1-x)Bisub(x)Fsub(1+2x) and Rbsub(1-x)Bisub(x)Fsub(1+2x)

Bragg neutron diffraction studies have been carried out on the fluorite type solid solutions Ksub(1-x)Bisub(x)Fsub(1+2x) (0.50 <= x <= 0.70) and Rbsub(1-x)Bisub(x)Fsub(1+2x) (0.50 <= x <= 0.60). The distribution of the fluorine atoms between normal and interstitial sites is given as a function of substitution rate. A substitution mechanism is proposed. Electrical and NMR results on one side and structural data on the other side are correlated. A study of the background as a function of temperature has allowed to determine the static origin of its modulation. By inelastic neutron diffusion, it has been shown that the number of carriers is weak, which involves a high mobility. (Auth.)