Intermediate valence behavior in

The novel ternary compound CeCo 9 Si 4 has been studied by means of specific heat, magnetization and transport measurements. Single-crystal X-ray refinements reveal a fully ordered distribution of Ce, Co and Si atoms with the tetragonal space group I4/mcm isostructural with other RCo 9 Si 4 . The smaller lattice constants of CeCo 9 Si 4 in comparison with the trend established by other RCo 9 Si 4 is indicative for intermediate valence of cerium. While RCo 9 Si 4 with R = Pr , … Tb , and Y show ferromagnetism and LaCo 9 Si 4 is nearly ferromagnetic, CeCo 9 Si 4 remains paramagnetic even in external fields as large as 40 T, though its electronic specific heat coefficient ( γ ≃ 190 mJ / mol K 2 ) is of similar magnitude as that of metamagnetic LaCo 9 Si 4 and weakly ferromagnetic YCo 9 Si 4 .