Growth of potassium niobate (KNbO3) single crystals for piezoelectric applications

Potassium niobate (KN) single crystals were successfully grown from a melt with potassium enriched composition 51.2 mole% K2CO3 using the TSSG technique. Colorless and crack-free crystals up to 27 x 27 x 10 mm(3) in size are reproducibly grown using a platinum crucible of 50 nun in diameter and 50 mm in height. The growth was along the (100) direction in the pseudo-cubic phase. The crystal was allowed to grow laterally from around 30 It to obtain the cross section desired. The growing crystal was then lifted up above the melt surface or lifted intermittently at the rate of about 0.5 mm/h, while the melt was cooled. Cracking occurred at the phase transition temperatures of 435 and 225 degrees C Slow cooling fairly eliminated the cracking at the both phase transition points.