Influence of morphological defects on thermophysical properties of $\gamma$-Gd$_{2}$S$_{3}$

The temperature dependences of the heat capacity $(C_p)$ and the thermal conductivity $(\kappa)$ in the temperature range from 300 to 773 K of polycrystalline gadolinium sulfide samples ($\gamma$-GdS$_ y$) with the deviation of the composition from the integer stoichiometric were studied. It was found that the thermal conductivity of gadolinium sulfides decreases monotonically and reaches 0.74 W/(m K) at $T$ = 773 K for the composition $y$ = 1.479, which is much lower than for the known single-crystal samples. The influence of morphological defects (boundaries of crystallites and dislocations) on the intensity of scattering of phonons is studied. It has been established that ceramic samples of gadolinium sulphides have a large heat capacity and a lower thermal conductivity, in comparison with monocrystalline samples of the same composition.