Thermal conductivity of Cu$_{2}$ZnGe$_{1-x}$Sn$_{x}$Se$_{4}$ alloys

Cu$_{2}$ZnGeSe$_{4}$ and Cu$_{2}$ZnSnSe$_{4}$ and Cu$_{2}$ZnGe$_{1-x}$Sn$_{x}$Se$_{4}$-alloy crystals are grown by the Bridgman method (vertical variant). The composition and structure of the crystals are determined. It is established that both the initial compounds and their alloys crystalize with the formation of tetragonal structure. The unit-cell parameters $a$ and $c$ of the crystals are calculated, and the dependences of these parameters on the composition of the alloys are constructed. It is shown that, under variations in the composition parameter $x$, the parameters $a$ and $c$ vary in accordance with Vegard's law. The thermal conductivity of the Cu$_{2}$ZnGeSe$_{4}$ and Cu$_{2}$ZnSnSe$_{4}$ compounds and Cu$_{2}$ZnGe$_{1-x}$Sn$_{x}$Se$_{4}$ alloys is measured in the temperature range 300–600 K. It is found that the thermal conductivity varies with $x$, with a minimum for the medium composition.