Glass-like properties observed in low-frequency Raman scattering of mixed fluorite crystals

Abstract

The low-frequency Raman spectra of(CaF2)1-x(LaF3)x mixed crystals in the concentration range from 0.05 < x < 0.4 have been measured as a function of temperature from 4.2 K to 295 K. Concentration dependent quasi-elastic Raman scattering is found for frequencies below 10 cm-1 for A1g + Eg scattering but not for T2g symmetry scattering. The temperature dependence of Raman intensity suggests that this effect is dominated by scattering from a distribution of two-level systems between 4.2 K and 20 K. The lowest impurity-induced vibrational Boson scattering peak at 82 cm-1 which shifts to higher frequency with increasing dopant concentration, also only appears in A1g + Eg symmetry, indicating that the two different kinds of glass-like excitations in these mixed crystals may have a common origin.

Publisher

Elsevier

Publication Date

8-1-1996

Publication Title

Journal of Non-Crystalline Solids

Department

Physics and Astronomy

Document Type

Article

DOI

https://dx.doi.org/10.1016/0022-3093(96)00346-8

Language

English

Format

text

Link to Full Text

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