An unusual O2−/F− distribution in the new pyrochlore oxyfluorides: Na2B2O5F2 (B = Nb, Ta)

摘要

Two new oxyfluorides with a pyrochlore-type structure, Na2Nb2O5F2 and Na2Ta2O5F2, have been obtained, for which the XRD crystallographic study coupled with 19F solid state NMR reveals an unusual O/F distribution. Both materials are n-type semiconductors exhibiting photoconductive properties.