Heat conductivity study of GaSe monocrystals

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Abstract
The thermal conductivity of laminated GaSe monocrystals is studied in two crystallographic directions between 90 and 600 °K. The thermal conductivity is highly anisotropic; the value in the direction parallel to the layers exceeds that in the direction perpendicular to the layers by almost an order of magnitude. The mean free path of the acoustic phonons is calculated on the basis of the experimental lattice thermal conductivity, sound velocity and heat capacity data. The mean free path in the direction perpendicular to the layers (\documentclass{article}\pagestyle{empty}$ l\frac{1}{{{\rm ph}}} = 15.8 \times {\rm 10}^{{\rm - 8}} {\rm cm} $ ) is found to be limited to the thickness of the Se—Ga—Ga—Se quadruple layers corresponding in this case to the lattice parameter (c = 15.883 Å). The mean free path in the direction parallel to the layers (l = 65 × 10−8 cm) exceeds the corresponding parameter (a = 3.734 Å) by an order of magnitude. Heat transfer by internal electromagnetic radiation is found in the high temperature region. A study is made of the effect of unilateral compression in the direction of the weak van der Waals bond (0001) both on the lattice and the photon components of the thermal conductivity of GaSe monocrystals.