Relation of Infrared Spectra to Coordination in Quartz and Two High-Pressure Polymorphs of SiO2

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Science  26 Oct 1962:
Vol. 138, Issue 3539, pp. 525-526
DOI: 10.1126/science.138.3539.525


Infrared spectra of the four-coordinated quartz and coesite polymorphs of SiO2, the rutile six-coordinated (stishovite) polymorph of SiO2, and the quartz and rutile polymorphs of GeO2 show that a change from tetrahedral to octahedral cation coordination results in (i) a 23-per-cent increase in the wavelength of the main absorption band for both the SiO2 and GeO2 polymorphs and (ii) a significant increase in the force constant of the same magnitude for the SiO2 and GeO2 polymorphs. The quartz and the rutile isostructural pairs for SiO2 and GeO2 show that the effect of increasing mass is to increase proportionally the wavelength of the respective main absorption bands. The infrared data for the rutile form of SiO2 fit the empirical equation of Dachille and Roy relating cation coordination, mass, atomic number, valence, and main absorption wavelength.