Crystal growth and intergrowth structure of the new heavy fermion materials CeIrIn5 and CeRhIn5

The structures of the new heavy fermion materials CeIrIn5 and CeRhIn5 have been determined by single-crystal neutron (R(F) = 0.051) and X-ray (R(F) = 0.056) diffraction, respectively. Both compounds adopt tetragonal structure , space group P4/mmm (No, 123), Z = 1, a = 6 = 4.674(1) Angstrom, and c = 7 .501(5) Angstrom for CeIrIn5, and a = b = 4.656(2) Angstrom, and c = 7.542( 1) Angstrom for CeRhIn5. The possible presence of antisite disorder, a long -standing question on this type of structure, was excluded by both electron and neutron or X-ray diffraction, The compounds are built by monolayers of face-sharing distorted cuboctahedra [CeIn3] and monolayers of edge-sharing rectangular parallelepipeds [RhIn2] or [IrIn2], stacked alternatively in t he [001] direction. Therefore, they are new members of the inhomogeneous li near homologous series MmTnT3m+2n'. Because of their ordered intergrowth st ructure, the physical properties of the quasi-two-dimensional heavy electro n systems CeIrIn5 and CeRhIn5 can be directly compared with the correspondi ng ones of their parent compound, the three-dimensional heavy fermion mater ial CeIn3, (C) 2001 Academic Press.