Synthesis and crystal growth of sillenite phases in the Bi2O3-TiO2-Nb2O5 system

The synthesis of Bi2O3-Nb2O5 sillenite phase (BNbO) and the solubility of this phase with Bi12TiO20 was investigated by solid-state reaction synthesis and niobium doped Bi12TiO20 (BTO:Nb) crystals were grown by the Top Seeded Solution Growth (TSSG) technique. The structures of polycrystalline compounds were checked by X-ray powder diffraction method at room temperature. The correct composition of the sillenite phase stabilized with niobium was determined as Bi-12[Nb0.17Bi0.83]O-19.7 (BNbO) with unit cell parameter a = 10.261(2) Angstrom. The system BTO-BNbO is poorly soluble, but niobium doped BTO crystals were grown from the liquid composition 10Bi(2)O(3) : xTiO(2): (1-x)/2 Nb2O5, with x = 0.95 and 0.90. A niobium concentration limit in the liquid phase is established in order to grow BTO:Nb with good crystalline quality. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.