The filled skutterudite CeOs$_{4}$As$_{12}$: a hybridization gap   semiconductor
  X-ray diffraction, electrical resistivity, magnetization, specific heat, and thermoelectric power measurements are presented for single crystals of the new filled skutterudite compound {\CeOsAs}, which reveal phenomena that are associated with f - electron - conduction electron hybridization. Valence fluctuations or Kondo behavior dominates the physics down to $T$ $\sim$ 135 K. The correlated electron behavior is manifested at low temperatures as a hybridization gap insulating state. The small energy gap $\Delta$$_1$/k$_B$ $\sim$ 73 K, taken from fits to electrical resistivity data, correlates with the evolution of a weakly magnetic or nonmagnetic ground state, which is evident in the magnetization data below a coherence temperature $T$$_{coh}$ $\sim$ 45 K. Additionally, the low temperature electronic specific heat coefficient is small, $\gamma$ $\sim$ 19 mJ/mol K$^2$. Some results for the nonmagnetic analogue compound {\LaOsAs} are also presented for comparison purposes. 
R. E. Baumbach, P. C. Ho, T. A. Sayles, M. B. Maple, R. Wawryk, T.   Cichorek, A. Pietraszko, and Z. Henkie