Electrical and magnetic properties of La$_{0.5}$Rh$_4$Sb$_{12}$ filled skutterudite synthesized at high pressure

A filled skutterudite, La$_{0.5}$Rh$_4$Sb$_{12}$, with a lattice constant of 9.284(2) Å was synthesized using a high-pressure technique. The electrical resistivity showed semiconducting behavior and the energy gap was estimated to be more than 0.08 eV. Magnetic susceptibility measurements indicated temperature-independent diamagnetism, which originates from Larmor diamagnetism. The electrical properties of this compound are more similar to those of the La$_{0.5}$Rh$_4$As$_{12}$ semiconductor with an energy gap of 0.03 eV than to those of the La$_{0.6}$Rh$_4$P$_{12}$ superconductor.