Crystal growth and characterization of Pb2KNb5O15

Lead potassium niobate crystals were grown by our pulling down method and tube-seed Czochralski method. Evaporation of lead and potassium was observed. Crystal growth was not so difficult despite the evaporation. Grown crystals were brownish and transparent. Cleavage was observed in the Czochralski grown crystals on the c-plane. After heat treatment, the dielectric constant along the c-axis was about 500-1000. A large dielectric constant above 10000 was observed on the ab-plane. On the ab-plane, almost isotropic properties were obtained on the basis of the dielectric constant and the thermal expansion coefficient.