Structures and magnetic properties of some layered iodides R2Co2I (R = La, Y, Pr, Nd, Tb–Ho)

The new compounds R2Co2I (R = Y, La, Pr, Nd, Tb–Ho) crystallize in the hexagonal Gd2Fe2I structure type (space group: P63/mmc, No. 194). Atomic coordinates have been derived from X-ray powder diffraction and a single crystal determination for Tb2Co2I. The data indicate a metric control as stability criterion for the Gd2Fe2I vs. La2Ni2I structure type. From magnetization measurements, ferromagnetic behavior has been observed for all investigated compounds. A deviation from the de Gennes rule for the light rare earth metal compounds is ascribed to a polarization of the 5d electrons.

New layered compounds R2Co2I (R = Y, La, Pr, Nd, Tb–Ho) have been prepared and their crystal structures and magnetic properties investigated. A stability criterion for the Gd2Fe2I vs. La2Ni2I structure type is proposed.Figure optionsDownload as PowerPoint slide