R12Pt7In (R=Ce, Pr, Nd, Gd, Ho)--new derivatives of the Gd3Ga2-type

A new compound Ce12Pt7In was synthesized and its crystal structure at 300 K has been determined from single crystal X-ray data. It is tetragonal, space group I4/mcm, Z=4, with the lattice parameters: a=12.102(1) A and c=14.542(2) A, wR2=0.1102, 842 F2 values, 33 variable parameters. The structure of Ce12Pt7In is a fully ordered ternary derivative of the Gd3Ga2-type. Isostructural compounds has been found to form with Pr (a=11.976(1) A, c=14.478(2) A), Nd (a=11.901(1) A, c=14.471(2) A), Gd (a=11.601(3) A, c=14.472(4) A), and Ho (a=11.369(1) A, c=14.462(2) A). Magnetic properties of Ce12Pt7In, Pr12Pt7In and Nd12Pt7In were studied down to 1.7 K. All three ternaries order magnetically at low temperatures with complex spin arrangements. The electrical resistivity of Ce12Pt7In and Nd12Pt7In is characteristic of rare-earth intermetallics