Flux Growth and Characterization of Layered K4Nb6O17 Crystals

Well-formed crystals of potassium hexaniobate (K4Nb6O17) were successfully grown from potassium molybdate and tungstate fluxes. The crystal growth of K4Nb6O17 was conducted by heating a mixture of solute and flux at 1100 °C for 10 h, followed by cooling to 500 °C at a rate of 5 °C/h-1. Colorless and transparent crystals having sizes up to 18 × 9.0 × 2.9 mm were grown from high-temperature solutions containing solute of 1−60 mol %. The crystal sizes were dependent on the solute concentration. The basic form was a plate bounded by the well-developed {010}, {110}, and {021} faces. Potassium, niobium, and oxygen were almost homogeneously distributed in the crystals. Furthermore, the grown K4Nb6O17 crystals exhibited a high activity for the dye adsorption and degradation. The degradation occurred via the photocatalytic process under ultraviolet light irradiation.