Accession Number : ADA132699

Title :   Low Frequency Raman Spectra of v-B2O3 as a Function of Temperature and Pressure.

Descriptive Note : Technical rept.,

Corporate Author : HOWARD UNIV WASHINGTON DC DEPT OF CHEMISTRY

Personal Author(s) : Guha,Soumyendu ; Walrafen,George E

PDF Url : ADA132699

Report Date : 08 Sep 1983

Pagination or Media Count : 50

Abstract : Raman studies of vitreous B2O3 have been conducted between 8 and 700K, and as a function of hydrostatic pressure (about 8 kbar) at room temperature. The low temperature Raman spectra exhibit two broad bands at 50/cm and 137/cm. From the temperature dependence of the 50/cm band, it has been concluded that the vibrational density of states in the low frequency region (30w300/cm) is better described when the Raman coupling coefficient C sub b varies as w. A shift in frequency of the Raman spectra as a function of temperature is attributed to a structural change near the glass transition. Near the glass transition temperature, the boroxol rings break up thereby leading to a more open structure. Above the melting point, i.e. when the viscosity is low, a regrouping of atoms occurs which results in a low density random network structure of BO3 triangles.

Descriptors :   *Boron oxides, *Glass, *Raman spectra, Vitreous state, Hydrostatic pressure, Room temperature, Broadband, Vibrational spectra, Density, Low frequency, Coupling(Interaction), Coefficients, Transition temperature, Low temperature, Atomic structure

Subject Categories : Ceramics, Refractories and Glass
      Atomic and Molecular Physics and Spectroscopy
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE