Distribution of tunneling-level barrier heights in (KBr)/sub 1-//sub x/(KCN)/sub x/: Comparison of dielectric response and specific heat

Journal Article · Thu Sep 15 00:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.38.6246· OSTI ID:6844787

Ernst, R M; Wu, L; Nagel, S R; Susman, S

We have measured the frequency-dependent dielectric response of the glassy crystal (KBr)/sub 1-//sub x/(KCN)/sub x/ for x = 0.25, 0.5, 0.7, and 1.0. From the data on the pure crystal, KCN, we cal- culate the asymmetry energy of the two-level states which form the tunneling centers in the glassy compositions. Using the dielectric data we calculate the low-temperature specific heat and compare with experimental data. We find this calculated specific heat to have the same magnitude, composition dependence, and time dependence as seen in those experiments. This gives strong support to a microscopic theory of the glassy dynamics of this system. We also find the data to be consistent with a mean-field theory of the quadrupolar ordering transition in (KBr)/sub 1-//sub x/(KCN)/sub x/. We relate the number of low-temperature tunneling levels to the quadrupolar transition temperature. The relevance of this microscopic model for understanding the glassy behavior in real structural glasses is discussed.

• Research Organization: James Franck Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637
• OSTI ID: 6844787
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 38:9
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
POTASSIUM COMPOUNDS
DIELECTRIC PROPERTIES
SPECIFIC HEAT
TUNNEL EFFECT
BROMIDES
CRYSTALS
CYANIDES
FREQUENCY DEPENDENCE
GLASS
LOW TEMPERATURE
QUANTITY RATIO
ALKALI METAL COMPOUNDS
BROMINE COMPOUNDS
ELECTRICAL PROPERTIES
HALIDES
HALOGEN COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
360204* - Ceramics
Cermets
& Refractories- Physical Properties