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- Author or Editor: A. M. Okaz x
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The thermal conductivity of LiKSO4 ferroelastic crystals was measured along the three principal crystallographic axes in the vicinity of its high temperature phase transition at 750 K. The data showed an anomalous behaviour in the temperature dependence of the thermal conductivity in the transition region of width of about 25 degrees. The anomaly in the phonon contribution to the conductivity was referred to the freezing-in of either optic-and/or acoustic-modes of lattice vibrations in the near vicinity of the phase transition. The results are discussed in terms of scattering mechanisms of energy carriers.
The method of determining the thermal conductivity depends upon a relation between the maximum temperature (θ m ) attained for a given current and potential difference (V) in a current carrying specimen. Heat is assumed to enter and leave specimen only through the surfaces through which electric current enters and leaves, other surfaces being insulated against flow of both heat and electricity. The plane ends of the rod were taken to be isothermal and equipotential surfaces held at a constant temperature.
A specific heat study of (Li1−xKx)2SO4 — LKS — mixed crystals has been made in a wide concentration rangex covering the temperature range 300–800 K. The phase diagram was determined. It is shown that a variation of the Li+:K+ concentration changes the critical behaviour of the specific heat. The results are discussed in terms of scattering mechanisms of energy carriers.
