Properties of Molten Potassium Niobate System

The density and surface tension of the K₂ O-Nb₂ O₅ molten system between 50 and 56mol% K₂ O melts were measured from 1080 to 1180°C. The concentration of K₂ O from 50 to 56mol% in melt not only caused the density of melt to decrease, but also induced the surface tension to decrease. Both composition gradient and the temperature coefficient of density exist extremum within this composition range. These properties are possibly employed to explain why the KNbO₃ crystal should be grown at the composition from 52 to 54mo1% K₂ O at above 1150°C.