Vibrational Spectra of Oxides with Molecular Lattice Structure
Studies of the vibrational spectra of the oxides P2O3 and P2O5 in the crystalline state, and of B2O3 in the glassy state, and comparison of the results with the results of other physicochemical investigations showed [4, 8–12] that these oxides have a molecular structure. It follows that among the glass-forming oxides, all of which should have a coordination structure according to the Zachariasen theory, several have a molecular structure. However, it was found that several more oxides, according to conjectures or results of various investigations, may be regarded as having a molecular structure. These are the oxides As2O3, Sb2O3, As2O5. It was shown by x-ray analysis  that As2O3 and Sb2O3 have a molecular structure. With regard to As2O5 there is merely a statement that, by analogy with P2O5, it should also have a molecular structure. According to the Zachariasen theory, all these oxides should form glasses. Unfortunately, we obtained only one (As2O5) in the glassy state. No data could be found in the literature concerning its structure in that state, apart from  where it is suggested from the analogy between the infrared absorption spectra of the crystalline and glassy forms that the structure is molecular.
KeywordsRaman Spectrum Vibration Frequency Selection Rule Vibrational Spectrum Point Group
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