Growth from high temperature solution and characterization of Pb(Fe2/3W1/3)O-3 single crystals

On the basis of a pseudo-binary phase diagram, single crystals of the complex perovskite Pb(Fe2/3W1/3)O-3 [PFW] have been synthesized from the high temperature solution growth using PbO or (PbO + B2O3) as flux. The growth results depend closely upon the flux composition, containing B2O3 or not. The PbO flux gives rise to PFW crystals with ferromagnetic appearance due to inclusions of a parasitic magnetic phase of trace amounts. The addition of small amounts (up to 1 wt%) of B2O3 to the PbO flux has, however, dramatically improved the growth results with purl single crystals of PFW showing a good optical isotropy without inclusions or internal stress, thus suitable for the subsequent physical characterization. The growth morphology was related to the growth conditions and to a layer growth mechanism for the {100} faces. The crystal structure of Pb(Fe2/3W1/3)O-3 belongs to the cubic <Pm(3)over bar m> group. A decomposition of the perovskite phase at the incongruent W melting point T-m=(930 +/- 3)degrees C was detected by DTA and X-ray diffraction. Frequency dispersion of the dielectric properties indicates a typical relaxer behaviour around the temperature of the maximum permittivity T-m=178 K.