Crystal structure and magnetic properties of Ce7Ni5±xGe3±xIn6 and Pr7Ni5±xGe3±xIn6

The indides Ce7Ni5±xGe3±xIn6 and Pr7Ni5±xGe3±xIn6 were synthesized from the elements by arc-melting of the components. Single crystals were grown via special annealing sequences. Both structures were solved from X-ray single crystal diffraction data: new structure type, P6/m, Z=1, a=11.385(2), c=4.212(1) Å, wR2=0.0640, 634F2 values, 25 variables for Ce7Ni4.73Ge3.27In6 and a=11.355(6), c=4.183(2) Å, wR2=0.0539, 563F2 values, 25 variables for Pr7Ni4.96Ge3.04In6. Both indides show homogeneity ranges through Ni/Ge mixing (M sites). This new structure type can be derived from the AlB2 structure type by a substitution of the Al and B atoms by CeM12 and NiIn6Ce3 polyhedra (tricapped trigonal prism). Magnetic susceptibility measurements on a polycrystalline sample of Ce7Ni5Ge3In6 indicated Curie–Weiss like paramagnetic behavior down to 1.71 K with the effective magnetic moment slightly reduced in relation to the value expected for trivalent cerium ions. No magnetic ordering is evident.