physica status solidi (b) · 1985 · 42 citations · 10 references
Natural SciencesMaterials SciencePhysicsCrystal StructureSolid State PhysicsSpectroscopyCrystal LatticeCrystal SymmetryInfrared SpectroscopyMolecular VibrationRaman SpectroscopyVibrational StructureChemical Bonding In CrystalsMolecular Force ConstantsMolecular Vibrational ModesRaman Spectral InterpretationSymmetry AnalysisVibrational Mode AnalysisVibrational Mode AssignmentVibrational Modes
Abstract An interpretation of the Raman and infrared phonon spectra in Bi 12 GeO 20 and Bi 12 SiO 20 crystals is proposed. Some quasi‐molecular units are distinguished due to the presence of heavy bismuth atoms in the crystal lattice. The frequencies of motion and the force constants of the tetrahedral GeO 4 and SiO 4 units are determined. Moreover, the frequencies of the stretching modes of A and F symmetry of the BiO bonds are considered and the stretching force constants for the BiO bonds are calculated. The results are in good agreement with the Raman and infrared data obtained in the recent works.
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