Method for producing high purity potassium fluorotantalate crystal or high purity potassium fluoroniobate crystal and recrystallization vessel for use in the method for production, and potassium flurotantalate crystal or high purity potassium fluoroniobate crystal produced by the method for production

摘要

It is an object to provide a product having a good crystal particle size distribution of a high-purity potassium fluorotantalate crystal or a high-purity potassium fluoroniobate crystal without using a physical method for particle classification. To that end, a method for manufacturing a high-purity potassium fluorotantalate crystal or a high-purity potassium fluoroniobate crystal is used, wherein the recrystallizing step comprising a first cooling process of cooling a saturated solution with a temperature of 60° C. to 90° C. obtained in the dissolving step at a cooling speed of T° C./hour until the solution temperature of the saturated solution becomes a temperature of the range of 35 to 50° C., and a second cooling process of cooling the solution at a cooling speed of [T-18]° C./hour to [T-1]° C./hour from the end of the first cooling process to the solution temperature becoming a temperature of 10 to 20° C.