Crystallization Region, Crystal Growth, and Phase Transitions of KNd(PO₃)₄

We determined the crystallization region of KNd(PO 3 ) 4 (KNP), the isotherms of saturation temperature, and three neighboring phases of this crystallization region, NdPO 4, Nd(PO 3 ) 3, and NdP 5 O 14, in the Nd 2 O 3 −K 2 O−P 2 O 5 system. We successfully grew KNP single crystals by the top seeded solution growth slow cooling method (TSSG). To optimize the growth process solution composition, seed orientation and rotation velocity were analyzed. We studied the evolution with the temperature of the KNP cell parameters in the room temperature to 773 K range, and the linear thermal expansion tensor of KNP was studied. We also studied the phase transitions of KNP in the room temperature to 1273 K range and found an irreversible decomposition at 1165 K. The second harmonic efficiency measured was at least similar to that of KH 2 PO 4 (KDP).