Neutron diffraction studies of Ce0.33U0.67C2 and Ce0.67U0.33C2 at 296–4 °K

Neutron diffraction measurements have shown that in the ternary CeC2‐type compounds, Ce0.33U0.67C2 and Cs0.67U0.33C2, the cubic NaCl‐type structure, which is usually stable above about 1000 °C, can be arrested down to 4 °K due to a large strain energy of the disordered lattice. Also retained down to 4 °K are a random distribution of Ce and U atoms, as well as the orientational disordering of C2 molecules. The lattice parameters at 296–4 °K indicate no valency change, such as Ce3+→Ce4+. Ce0.33U0.67C2 showed no magnetic ordering at 296–4 °K in 0–21 kOe. Ce0.67U0.33C2 becomes a weak ferromagnet below 17 °K in 21 kOe, with the moment direction parallel to the [111] direction.

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