Structures, spectra and related properties of group IVB-doped vitreous silica

Abstract

Vibrational spectra and related physical properties were analyzed for titanium-, zirconium- and hafnium-containing vitreous silicas on the basis of glass structure. Linear functional relationhips were found between both partial molar volume and refractivity, and the dopant concentration throughout the dopant range examined. Analysis of the data suggested four-fold coordination with oxygen atoms by titanium atoms with greater coordination by zirconium and hafnium atoms. Raman and difference infrared spectra for these glasses showed an intensity decrease of the v 3 (F 2) band at 1068 cm −1 accompanied by the emergence of a band at circa 950cm −1 whose exact wavenumber was defined by the dopant species ( gv Hf > gv Zr > gv Ti ) and, in the case of TiO 2- containing glasses, a band at 1110 cm −1. The intensities of these bands were proportional to the dopant concentration. Empirical spectral analysis suggested that upon TiO 2 addition Ti-atoms bonded to a single oxygen atom of a SiO 4-unit, while upon zirconia and hafnia addition each metal atom bonded to two oxygen atoms of a SiO 4-unit. These structural models were consistent with ion coordination predictions based upon the physical property measurements.