Structural and magnetic properties of the new R2Li2Si3 compounds (RÂ =Â La, Ce, Pr, Nd, Sm)

The R2Li2Si3 compounds, with R = La, Ce, Pr, Nd and Sm, synthesized and structurally studied by powder and single crystal X-ray diffraction, belong to the Ce2Li2Ge3 orthorhombic type. The magnetization and heat capacity data show the occurrence of normally trivalent cerium ions in Ce2Li2Si3 ordering ferromagnetically at 17 K. Pr2Li2Si3 becomes antiferromagnetic at 18 K, its isothermal magnetisation at 1.8 K showing a field induced spin flip transition at 25 kOe. For Nd2Li2Si3 the transition to the antiferromagnetic state occurs at 9.5 K. Two peaks are seen in the heat capacity data of Ce2Li2Si3 and Nd2Li2Si3 which can be attributed to either two symmetry inequivalent rare earth sublattices ordering at different temperatures or to spin re-orientation.