Raman Spectra and Structure of Certain Inorganic Types of Glass

Abstract

Illinois 601 15. USC M S . received 14th M a y 1970Ahtract. Starting from bare-ion pseudopotentials, net crystal potentials are evalutiied in direct space by (a) the usual linear screening technique and (b) the Thomas-Fermi method. For the metals considered (Na and AI), the potentials are quite similar, crossing outside the cores and never differing by more than 0.02 a.u. in the case of Na nor by more than 0.2 a.u. in the case of Al. The similarity of the results based on (a) and (b) suggest the use of the pseudopotential concept in conjunction with the rather general method (b) under conditions when (a) is questionable, that is whenever the zeroth order uniform electron gas solution is a poor physical approximation to the actual system under study (specific examples being molecules, insulating solids and interfaces).Methods (a) and (bj both yield shallower wells than those most often used as input information in band structure calculations and obtained by superposing atomic data.

Searching for correlations between vibrational spectral features and structural parameters of silicate glass network

“…Based on the fact that the increase in sodium concentration in the sodium silicate glass will increase the Si–NBO fraction, the growth of the Raman band in the 1050‐1200 cm −1 region has been attributed to the increase in the Q 3 species concentration . In the literatures interpreting the Si–O stretch spectral features in this way, the Raman bands were often deconvoluted into four components: Q 4 species at 1200 cm −1 , Q 3 species at 1050~1100 cm −1 , Q 2 species at 950~1000 cm −1 , and Q 1 species at 850~900 cm −1 .…”

Raman scattering and quantum confinement in heavily electron-irradiated alkali halides

“…The peak positions of the above-mentioned lines at 330-550 cm −1 are almost independent of the temperature, which is quite unusual for Raman scattering peaks. According to [20,22] the frequency position of the RS lines should decrease with increasing temperature. As can be seen in table 2, where the peak positions at temperatures between 30 up to 200 K are given for the samples investigated in this paper, the downward shift is usually about 4-5 cm −1 for the peaks at 160 and 207 cm −1 .…”

The structural investigations of PbO–P2O5–Sb2O3 glasses with MoO3 as additive by means of dielectric, spectroscopic and magnetic studies

“…Clearly this peculiar behavior, which distinguishes lead from alkali and alkaline earth metals, depends on the electronic structure of the Pb 2+ ion. In fact the easily polarizable valence shell of the Pb 2+ ion strongly interacts with highly polarizable O 2À ion, giving rise to a rather covalent Pb-O bond [8].…”