CRYSTAL-GROWTH OF K(TA1-XNBX)O3 SOLID-SOLUTIONS

Single crystals of K(Ta1-xNbx)O3 with compositions 0. 30<1 are grown from solutions with an excess of K2O. In order to minimize striations due to temperature fluctuations a method is applied similar to that known for the crystallization in aqueous solutions. With optimized growth conditions this kind of striations is fairly reduced. However, another type, so-called type II striations, is observed. They are formed by terraces at the growth interface. It is shown by electron microprobe measurements that the Nb/Ta ratio depends very strongly on the height of the terraces. In order to reduce type II striations Rb2O is given to the solution and forced convection is applied. It is possible to restore the excess of K2O completely by Rb2O. As a result the crystals grown from these solutions are nearly striation-free. They are suitable for optical second harmonic generation (SHG) and holographic experiments. © 1991, Taylor & Francis Group, LLC. All rights reserved.