METHOD FOR PRODUCING POTASSIUM FLUOROTANTALATE CRYSTAL BEING LOW IN OXYGEN CONTENT AND METHOD FOR PRODUCING POTASSIUM FLUORONIOBATE CRYSTAL BEING LOW IN OXYGEN CONTENT, POTASSIUM FLUOROTANTALATE CRYSTAL BEING LOW IN OXYGEN CONTENT AND POTASSIUM FLUORONIOBATE CRYSTAL BEING LOW IN OXYGEN PRODUCED BY THE METHODS, A

摘要

A method for producing potassium fluorotantalate crystals wherein a saturated potassium fluorotantalate solution comprising hydrofluoric acid is cooled in a controlled manner to form recrystalized crystals and the resultant recrystalized crystals are separated by filtration, followed by drying in a drying device, charcterized in that the saturated potassium fluorotantalate solution comprising hydrofluoric acid contains hydrofluoric acid in a concentration of 0.5 mol/l to 10 mol/l; and a method for producing potassium fluoroniobate crystals similar to the above method for potassium fluorotantalate crystals; crystals produced by said methods; and methods for analyzing these crystals.