Raman spectroscopy study of sillenites. II. Effect of doping on Raman spectra of Bi 12TiO 20

Abstract

Raman spectra of single crystals of Bi 12TiO 20 doped with various cations, X (X=Al, P, V, Cr, Mn, Cu, Cd, Co, W, Mo, Nd, Ag), were measured. The results show that doping of Bi 12TiO 20 changes the ratio between the intensities of the transverse and the longitudinal components of the anti-symmetric Ti–O stretching mode. Doping with Ag, Cu and V, generates an additional peak at about 792 cm −1 resulting from the local symmetric stretching mode of XO 4 tetrahedra. Doping with P shifts, the peaks sensitive to the geometry of the BiO n polyhdera, which indicates that the Bi–O framework in Bi 12TiO 20:P rearranges, in order to embed the second type of tetrahedral cations of a much smaller ionic radius.