Raman scattering of B203 has been performed from room temperature to 1273 K to study structural changes as the glass transforms into the melt via the supercooled regime. It is found that a structural model containing threefold six-member planar boroxol rings and chains of BO3 triangles can explain the experimental spectra. From the behavior of the internal vibrations of the boroxol rings and the BO3 triangles, we conclude that these molecular units do not change significantly as the temperature increases whereas the connectivity of the units is strongly affected. Still, network connectivity is observed in this "strong" liquid far above T, where the presence of transverse acoustic modes have also been reported.This supports the idea of a relation between structural properties and the dynamics of the liquid-glass transition as suggested in the "strong-fragile" classification scheme. The structural changes are demonstrated by the intensity profile of the spectra. It is shown that the strongest vibrational mode at 808 cm, attributed to the breathing mode of boroxol rings, decreases rapidly in intensity as the temperature is raised above the glass transition temperature Tg. The high-frequency multicomponent band at 1200-1600 cm also displays anomalous temperature behavior above Tg. A significant redistribution of the intensity from the two narrow lines at -1210 and -1260 cm ' into the broad band at -1325 cm is found. The observed effects are consistent with a gradual breakup of boroxol rings, which change into chains of BO3 triangles as the temperature increases above Tg. From a detailed analysis of the temperature dependence of the spectra, the structure is estimated to consist of about half of the number of atoms in boroxo1 rings at Tg. Heating the glass to the melting temperature leads to breaking of about -, ' of the boroxol rings.

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The low frequency Raman spectrum of B203 and the boroxol ring vibrational mode at 808 cm-1 have been studied from room temperature to 1273 K as the glass transforms to a melt. Both the low frequeney "boson" peak and the boroxol mode are markedly influenced by the glass transition. Raising the temperature above Tg the strength of the 808 cm-1 mode decreases linearly indicating the Similar behavior of the boroxol ring concentration. The boson peak shows a different temperature behavior, which mirrors that of the sound velo city. The structural correlation length demostrates the same correlation range in the liquid and the glass. The results, when compared with neutron diffraction measurements contradict a recently proposed relation between the "boson correlation length" and the position of the first sharp diffraction peak of the structure factor.

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