The electrical conductivities of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids and of 1-hexyl-3-methylimidazolium ionic liquids with different anions were determined in the temperature range between 123 and 393 K on the basis of dielectric measurements in the frequency range from 1 to 10(7) Hz. Most of the ionic liquids form a glass and the conductivity values obey the Vogel-Fulcher-Tammann equation. The glass transition temperatures are increasing with increasing length of the alkyl chain. The fragility is weakly dependent on the alkyl chain length but is highly sensitive to the structure of the anion.

An improved technique employing the photopyroelectric effect to measure thermal conductivity and heat capacity simultaneously near solid state phase transitions is reported. A calibration procedure adaptable to the use of a pyroelectric detector on a thermally thick backing medium is described in detail. A quantitative comparison of the predictions of the theory with experimental results on selected known samples is used to test the applicability of the method as a practical technique. The variations of the thermal diffusivity (αs), thermal effusivity (es), thermal conductivity (Ks) and heat capacity (cps) near the para-ferroelectric phase transition in single-crystalline triglycine sulphate at 49.4 °C cut along various axes are reported and compared with available experimental data. The method can be adapted to the measurement of these parameters during any kind of phase transition in solids, the only limitation being the temperature range over which the sensitivity of the pyroelectric detector remains sufficiently high.

La 0.5 Sr 0.5 Co 1−x Ni x O 3−δ  (0⩽ x ⩽0.6) ceramics were prepared using a conventional solid-state ceramic route. The thermal properties—thermal conductivity and heat capacity—of these ceramics were measured by the photopyroelectric technique. The thermal conductivity was found to increase with increasing Ni content. These materials were also found to exhibit a metallic-type variation of thermal conductivity with temperature, and no metal-insulator (M-I) transition was found to occur in any of the samples prepared by this route. However, a M-I transition was found to occur in La0.5Sr0.5CoO3−δ samples prepared by hot pressing. The difference is attributed to variations in oxygen content in the samples.

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Thermal conductivity, thermal effusivity, and specific heat capacity near the lower critical point of the binary liquid mixture n-butoxyethanol-water One-dimensional heat conduction model for an electrical phase change random access memory device with an 8F 2 memory cell (F=0.15μ m ) J. Appl. Phys. 94, 3536 (2003); 10.1063/1.1598272Carrier-type reversal in metal modified chalcogenide glasses: Results of thermal transport measurements