The structure and dielectric properties of new oxyfluorides

The structure of solid solution Bi/sub 1.5/(Zn/sub 1-x/Li/sub x/)Nb/sub 1.5/(O/sub 7-x/F/sub x/) obtained by substitution of oxygen by fluorine in the oxide Bi/sub 1.5/ZnNb/sub 1.5/O/sub 7/ is cubic pyrochlore for 0/spl les/x/spl les/0.15. For 0.80/spl les/x/spl les/1.00, a distorted modification with low symmetry results, while the mixed phases of the above two are formed for other values of x between 0.15 and 0.80. The temperature dependences of the dielectric constants have been studied, and a dielectric anomaly at low temperatures (less than 100/spl deg/C) has been observed.