STABILITY OF KH2PO4 AND K(H,D)(2)PO4 SOLUTIONS AT FAST CRYSTAL-GROWTH RATES

The stability of KH2PO4 (KDP) and K(H,D)(2)PO4 (DKDP) solutions was investigated under the conditions required for rapid growth of large crystals. A metastable zone of up to 40 degrees C in width and induction periods of more than 3 months were obtained in stirred solutions. Values for the surface free energy, alpha, of 11.9 and 12.9 mJ/m(2) were calculated for 40 and 30 degrees C, respectively. High quality single crystals of 5-16 cm in size were grown at growth rates of 10-40 mm/day without spontaneous nucleation.