Specific Heat of UOs2 and UOsIr

The low temperature specific heats of C-15 structure UOs₂ and UOsIR have been measured in order to compare them with the systems NpOs₂, a ferromagnet with T_{Curie = 7.9 K}, and NpOsIr, newly discovered to be a spin fluctuation system with a specific heat γ of 375 mJ mol⁻¹ K⁻². The uranium compounds, with U—U separations of 3.25 Å, less than the Hill limit of 3.4 Å, show normal metallic behavior, with γ(UOs₂) = 20 ± 2 mJ mol⁻¹K⁻² and γ(UOsIr) = 33 ± 3 mJ mol⁻¹ K⁻².