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Undoped and Er-doped NaY(WO4)2 disordered single crystals have been grown by the Czochralski technique. The specific heat and thermal conductivity (κ) of these crystals have been characterized from T = 4 K to 700 K and 360 K, respectively. It is shown that κ exhibits anisotropy characteristic of single crystals as well as a κ(T) behavior observed in glasses, with a saturation mean free phonon path of 3.6 Å and 4.5 Å for propagation along a and c crystal axes, respectively. The relative energy positions and irreducible representations of Stark Er(3+) levels up to (4)G(7/2) multiplet have been determined by the combination of experimental low (

Abstract The preliminary results of thermal conductivity experiment carried out on solid CD4 at equilibrium vapor pressure in the temperature range 1.2–30 K are reported. The dependence of the thermal conductivity on temperature shows a clear change at the temperatures 27.0 and 22.1 K, which correspond to the phase transitions, from phase I to II and from phase II to III, respectively. In the orientationally ordered phase III of the deuterated methane, the thermal conductivity of CD4 depends on thermal history of the sample. [ABSTRACT FROM AUTHOR]