Thermal decomposition of lithium-inserted NbO2F

Article abstract of DOI:10.1016/0022-5088(89)90414-1

The thermal decomposition of lithium-inserted NbO₂F was studied by differential scanning calorimetry. Samples of Li_xNbO₂F (O ≤ x ≤ 1.8) were heated to 800 and 950 K. The thermograms revealed that decomposition started within the temperature range 640 - 780 K, followed by a second step at approximately 900 K. The products were characterized by X-ray powder diffraction and electron diffraction patterns and by high-resolution electron microscopy. The following phases were obtained at 800 K: LiF, NbO₂F, the low pressure form of Nb₃O₇F, and lithium-enriched forms of P-Nb₂O₅, NbO₂ and LiNbO₃. At 950 K, NbO₂F disappeared, and LiNb₃O₈ and the high pressure form of Nb₃O₇F coexisted with the other phases obtained at 800 K. The formation of structures built up of approximately hexagonally close-packed anion arrangements is discussed.