Volume 34, Issue 8, August 2008
Index of content:
- LOW-DIMENSIONAL AND DISORDERED SYSTEMS
34(2008); http://dx.doi.org/10.1063/1.2967510View Description Hide Description
The thermal expansion of samples of high-density nanoceramic CuO is investigated. The nanoceramic is obtained by the method of loading coarse-grained copper oxide by spherically convergent shock waves. Anomalous behavior of the thermal expansion coefficient of the oxide is observed in the temperature region below . The appearance of these anomalies is explained by the presence of orientationally degenerate tunneling centers and/or low-temperature phase separation.
34(2008); http://dx.doi.org/10.1063/1.2967511View Description Hide Description
The effect of proton ordering in tetrahydrofuran hydrate is detected using a technique based on measurement of thermal conductivity. The thermal conductivity of tetrahydrofuran hydrate is measured by the steady-state potentiometric method in the interval . Two regimes are selected to observe the effect: (i) slow cooling of the hydrate sample, and (ii) doping of the hydrate with a small quantity of KOH alkali to a concentration of . Proton ordering affects the temperature dependence of the thermal conductivity, changing its glass-like behavior to crystal-like below . The phonon maximum that appears in the temperature dependence of the thermal conductivity at is attributed to the cooperative process of local proton ordering stimulated by orientational and ionic defects.