Powder samples of the Cr6+-containing compound Bi6Cr2O15 were prepared by solid state reaction of Bi2O3 and Cr2O3 in air at 650C. The structure was solved and refined by using high-resolution neutron powder diffraction data in space group Ccc2, with anisotropic thermal displacement parameters a = 12.30184, b = 19.87492 and c = 5.88162Å, V = 1438.0Å3, and 126 variables to RF = 1.8%. Bi6Cr2O15 exhibited a new structure type that contains (Bi12O14)8n+n columns, of the kind previously found only for phases isotypical with Bi13Mo4VO34. Each column was surrounded by eight CrO2-4 tetrahedra. The ionic conductivity of Bi6Cr2O15 was determined by impedance measurements to be 3.5 x 10-5S/cm at 600C.

Structure and Ionic Conductivity of Bi6Cr2O15 - a New Structure Type Containing (Bi12O14)n8n+ Columns and CrO42- Tetrahedra. J.Grins, S.Esmaeilzadeh, S.Hull: Journal of Solid State Chemistry, 2002, 163[1], 144-50