Properties of Molten Potassium Niobate System

The density and surface tension of the K2O-Nb2O5 molten system between 50 and 56 mol% K2O melts were measured from 1080 to 1180°C. The concentration of K2O from 50 to 56 mol% 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 54 mol% K2O at above 1150°C.