RAMAN-SPECTRA OF PHOSPHATE AND SILICATE-GLASSES DOPED WITH THE CATIONS TI, NB AND BI

The Raman spectra of various cation-modified sodium phosphate, sodium aluminum phosphate, and sodium silicate glasses are reported. As Ti is added to phosphate glass, these spectra indicate that it first enters into tetrahedral and then, as more is added, into octahedral sites and becomes part of the glass-forming network. Addition of Bi as well as Ti changes the Raman spectra very little, which implies that Bi does not occupy chain-forming sites. If Nb is included in addition to Ti, alterations in the spectra show that Nb also enters octahedral sites. In silicate glasses as in phosphate glasses, Ti enters tetrahedral and octahedral sites in the chain-forming network. However, in silicate glasses, the Ti-sensitive modes are dominant, whereas in the phosphate glasses doped with Ti all modes are nearly equal in intensity. This equality indicates that the polarizability of the Ti-sensitive modes in the silicate glasses is greater than those of modes involving mainly silicon and oxygen motion as compared with those involving mainly phosphorus and oxygen motion.