Glassy behavior of crystalline solids at low temperatures

Abstract

Measurements of low-temperature specific heat $C$, thermal conductivity $\ensuremath{\kappa}$, and dielectric dispersion have been made on crystalline samples of the superionic conductor ${\mathrm{Li}}_{3}$N, the oxygen conductor ${\mathrm{Y}}_{2}$${\mathrm{O}}_{3}$-stabilized Zr${\mathrm{O}}_{2}$, and the relaxation ferroelectric ${\mathrm{Pb}}_{3}$ (Mg${\mathrm{Nb}}_{2}$)${\mathrm{O}}_{9}$. In each case, the behavior is similar to that found in amorphous materials. Data on other crystalline materials are reviewed to emphasize that the low-temperature phenomena found in glasses can occur in crystals. It is shown that a peak in $\frac{C}{{T}^{3}}$ appears to be correlated, in both amorphous and crystalline materials, with a nearly temperature-independent regime (plateau) in $\ensuremath{\kappa}$.