Phys. Rev. B 38, 597–605 (1988)Direct observation of relaxation modes in KNbO3 and BaTiO3 using inelastic light scatteringReceived 14 January 1988; published in the issue dated 1 July 1988 Cubic and tetragonal BaTiO3 and orthorhombic KNbO3 have been studied by Raman scattering, using an iodine filter to eliminate elastically scattered light. In addition to the usual phonon features, such as the soft E mode in tetragonal BaTiO3 and the soft B2 mode in orthorhombic KNbO3, central components have been observed in both materials for the first time. These components have the linewidths, line shapes, and thermal properties of relaxation modes, and symmetry properties consistent with an eight-site order-disorder model of the successive phase transitions. Additionally, the data provide direct evidence that clusters of precursor order are present in cubic BaTiO3 and the model provides estimates of the temperatures at which these clusters are present in both BaTiO3 and KNbO3. These values are in good agreement with the results of linear birefringence and refractive-index measurements. © 1988 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.38.597
DOI:
10.1103/PhysRevB.38.597
PACS:
77.80.Bh, 78.30.Ly
See AlsoComment: M. D. Fontana, G. E. Kugel, and C. Carabatos-Nedelec, Comment on ‘‘Direct observation of relaxation modes in KNbO3 and BaTiO3 using inelastic light scattering’’, Phys. Rev. B 40, 786 (1989). Reply: J. P. Sokoloff, L. L. Chase, and D. Rytz, Reply to ‘‘Comment on ‘Direct observation of relaxation modes in KNbO3 and BaTiO3 using inelastic light scattering’ ’’, Phys. Rev. B 40, 788 (1989). |
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