On the existence of a pyrochlore-type phase in the system Bi2O3–TiO2
The existence of a bismuth titanate in the range between Bi 2 Ti 4 O 11 (Bi 2 O 3 . 4 TiO 2 ) and Bi 4 Ti 3 O 12 (2 Bi 2 O 3 . 3 TiO 2 ) has been investigated by X-ray diffraction of samples prepared by solid state reactions. For reaction temperatures above 1100 °C and a starting composition Bi 2 O 3 . 2 TiO 2 there appeared additional lines which could be attributed to a cubic face-centred cell with a = 10.354 A. A multiphase Rietveld analysis based on X-ray powder diffraction data confirmed the structural model of a pyrochlore for this compound. There is evidence that this phase belongs to the group of defect pyrochlores with a Bi 3+ -deficiency resulting in a composition of Bi 1.833 Ti 2…