D. Makovec et al., Incorporation of aliovalent dopants into the bismuth-layered perovskite-like structure of BaBi4Ti4O15, J AM CERAM, 84(11), 2001, pp. 2702-2704
The solid solubility of the aliovalent dopants Fe3+ and Nb5+ in the BaBi4Ti
4O15 compound, a member of the family of Auri-villius bismuth-based layer-s
tructure perovskites, has been studied using quantitative wavelength-disper
sive spectroscopic microanalysis (SEM/EPMA) in combination with X-ray powde
r diffractometry (XRPD). The samples with nominal (starting) compositions c
orresponding to the chemical formulas BaBi4Ti4-4xFe4xO15 and BaBi4Ti4-4xNb4
xO15 were prepared by hot forging a mixture of BaTiO3 and Bi4Ti3O12 with ad
ditions of Fe2O3 or Nb2O5 followed by a long annealing at 1100 degreesC. Th
e study showed that an excess charge introduced into the structure by the s
ubstitution of Ti4+ ions with aliovalent dopants was preferentially compens
ated by a change in the ratio of Ba2+ to Bi3+ ions in the host structure ac
cording to the general formulas of the solid solutions Ba1-4xBi4+4xTi4-4xFe
'O-4x(15) and Ba1+4xBi4-4xTi4-4xNb4xO15.