Study of lattice instabilities in ${\mathrm{Sn}}_x{\mathrm{Eu}}_{y-x}{\mathrm{Mo}}_6{\mathrm{S}}_8$ ($y=1.0\mathrm{} \mathrm{and} 1.2$)

An anomaly in the heat capacity of ${\mathrm{Eu}}_{1.2}$${\mathrm{Mo}}_6$${\mathrm{S}}_8$ at ∼120 K ($T_0$) has been observed and identified as a structural transformation. The heat capacity, electrical resistance, and Hall coefficient for the Eu-rich pseudoternaries have been measured under pressure to obtain the pressure dependence of $T_0$. The depression of $T_0$ by pressure is used to explain the pressure dependence of the superconducting transition temperature and the anomalous temperature dependence of the critical field.