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Solid solution crystals of ternary 1:1 (PbSc½Ta½O3-PbSc½Nb½O3) and 1:2 (PbMg⅓Nb2/3O3-PbSc½Nb½O3) perovskites were grown from the flux. X-ray supercell reflections due to B-cation ordering were observed for as-grown crystals. The same regularities of cation ordering during the crystal growth were found to be valid for both systems: the disordered structure is formed first even when the crystallization temperature is much lower than the temperature Tt of the compositional order-disorder phase transition and the disordered state is non-equilibrium. The ordering then starts via a diffusion-type mechanism, its rate depending greatly on the relation of crystallization temperature and Tt. [ABSTRACT FROM AUTHOR]

(1 - x )PbMg 1/3 Nb 2/3 O 3 -( x )PbSc 1/2 Nb 1/2 O 3 solid solution crystals have been grown by the flux method. X-ray supercell reflections due to B-cation ordering were observed for crystals in the 0.1 < x < 0.65 compositional range. In as-grown crystals diffuseness of dielectric permittivity maximum is the lowest for x = 0.65 composition and increases toward the end members of solid solution. Such behavior is assumed to be due to the random-site ordering of B-site cations and non-monotonic dependence of the compositional order-disorder phase transition temperature on concentration. [ABSTRACT FROM AUTHOR]