A method for the production of potassium fluorine niobate - crystals as well as potassium fluorine niobate - crystals

摘要

The present invention discloses a process which can yield potassium fluoroniobate crystals having a large particle diameter and high quality in high yield, although advantageous in material cost and raw-material-dissolving operation. The process comprises (a) a first step which comprises adding a potassium-based electrolyte to a feedstock solution containing niobium to precipitate crude potassium hydroxyfluoroniobate crystals and/or crude potassium fluoroniobate crystals and taking out the crude crystals by filtration and (b) a second step which comprises heating to 50 DEG C or higher a recrystallization solvent comprising a 12 to 35 wt.% aqueous solution of hydrofluoric acid, subsequently dissolving the crude crystals in the recrystallization solvent, and then cooling the resultant solution to 40 DEG C or lower at a rate less than 20 DEG C/h.