  The filled skutterudite compound SmOs_{4}Sb_{12} was prepared in single
crystal form and characterized. The SmOs_{4}Sb_{12} crystals have the
LaFe_{4}P_{12}-type structure with lattice parameter a = 9.3085 Angstroms.
Specific heat measurements indicate a large electronic specific heat
coefficient of ~880 mJ/mol K^{2}, from which an enhanced effective mass m^{*} ~
170 m_{e} is estimated. The specific heat data also suggest crystalline
electric field (CEF) splitting of the Sm^{3+} J = 5/2 multiplet into a
Gamma_{7} doublet ground state and a Gamma_{8} quartet excited state separated
by 37 K. Electrical resistivity rho(T) measurements reveal a decrease in rho(T)
below ~50 K that is consistent with CEF splitting of ~33 K between a Gamma_(7)
doublet ground state and Gamma_{8} quartet excited state. Specific heat and
magnetic susceptibility measurements display a possible weak ferromagnetic
transition at ~2.6 K, which could be an intrinsic property of SmOs_4Sb_{12} or
possibly due to an unknown impurity phase.
