Structural and thermopower studies of CeNiAl4- and CeNiIn4-related compounds

The CeNi1-xCoxAl4 (x=0-0.50, CeNiIn4-x Ga-x (x=0-0.75), and CeNiAl4-xInx (x =0-0.25) soild solutions are isotypic to CeNiAl4 a known intermediate valen t (IV) material. We present the lattice parameters and temperature dependen ces of the Seebeck coefficients for a range of alloys from each of these so lid solutions. In several cases, including CeNi0.75Co0.25Al4 and CeNiGaIn3, the thermopowers of these alloys are significantly higher than those for t he parent compounds (x=0). We also report strong evidence for stacking faul ts in single crystals of some of these materials. (C) 2000 Elsevier Science S.A. All rights reserved.