Crystal structures of the trifluorides, trichlorides, tribromides, and triiodides of americium and curium

Article abstract of DOI:10.1021/ic50029a013

The previously unreported lattice constants and crystal symmetries of the trifluoride, trichloride, tribromide, and triiodide of curium are given. Similar data for the isostructural trihalides of americium (except for the trifluoride) have been redetermined to a higher degree of precision. Correlations have been made between these actinide trihalides and the corresponding lanthanide trihalides. Curium trifluoride is hexagonal, LaF₃-type, space group P6₃/mmc-D_6h⁴. Americium and curium trichlorides are hexagonal, UCl₃-type, space group P6₃/m-C_6h². The tribromides are orthorhombic, PuBr₃-type, space group Cmcm-D_2h¹⁷. The triiodides are hexagonal, BiI₃-type, space group R3-C_3i². When treated with hydrogen at elevated temperatures, no reduction of these trivalent americium or curium trihalides was observed.