Transformation of Dion-Jacobson-type layered oxyfluorides into new anion-deficient pyrochlore-type oxides, ASrNb_2O_(6.5) (A = Li and Na)

摘要

New pyrochlore-type oxides, ASrNb_2O_(6.5) (A = Li and Na), were prepared from Dion-Jacobson-type layered perovskite oxyfluorides, ASrNb_2O_6F. The prototype layered perovskite phases are transformed into anion-deficient pyrochlore-type oxides by heating above 600 deg C in air. The ASrNb_2O_6F (A = Rb and K) and RbCaNb_2O_6F compounds have the layered perovskite structure, whereas the pyrochlore structure is found to be more stable than the layered perovskite in the AF-SrNb_2O_6 (A = Li and Na) and KF-CaNb_2O_6 systems.