Transport and magnetic properties are reported for ternary skutterudites ${\mathrm{La}}_{0.83}{\mathrm{Fe}}_4{\mathrm{Sb}}_{12}$ and ${\mathrm{Pr}}_{0.73}{\mathrm{Fe}}_4{\mathrm{Sb}}_{12}.$ Physical properties of ${\mathrm{Pr}}_{0.73}{\mathrm{Fe}}_4{\mathrm{Sb}}_{12}$ are dominated by crystal electric field effects, yielding in the magnetic triplet ${\Gamma }_5$ as ground state. As a result, long-range magnetic order appears below 4.6 K. ${\mathrm{Pr}}_{0.73}{\mathrm{Fe}}_4{\mathrm{Sb}}_{12}$ exhibits an unusually high electronic contribution to the specific heat $C_p/T$ of several hundred ${\mathrm{m}\mathrm{J}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{}\mathrm{K}}^2,$ and a significant value of a nuclear Schottky contribution is derived below about 1 K, primarily related to ${}^{141}\mathrm{Pr}$ with a nuclear spin $I=5/2.\mathrm{}$ The figure of merit at room temperature, expressing the thermoelectric performance of ${\mathrm{Pr}}_{0.73}{\mathrm{Fe}}_4{\mathrm{Sb}}_{12},$ is about 0.075.

We report on measurements of the magnetic penetration depth of polycrystalline samples of nonmagnetic Mo${}_3$Al${}_2$C ($T_c=9$ K) without inversion symmetry. Two previous specific-heat measurements in this compound found different anomalous peaks in the low-temperature limit. One of these peaks was attributed to the superconducting transition at 3 K of the impurity phase Mo${}_2$C. We argue here that the second anomalous peak may be caused by the superconducting transition of SiC:Al at 1.45 K, another impurity phase possibly present in Mo${}_3$Al${}_2$C samples. The temperature-independent behavior of the penetration depth observed below 0.5 K is taken as firm evidence for the presence of a nodeless superconducting gap in Mo${}_3$Al${}_2$C. Numerical calculations using the BCS expression for the penetration depth give qualitative support for an isotropic energy gap in Mo${}_3$Al${}_2$C. The present results suggest that Mo${}_3$Al${}_2$C is a conventional $s$-wave superconductor, although two-gap or anisotropic-gap superconductivity cannot be ruled out.