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

The CeNi1-xCoxAl4 (x=0-0.5), CeNiIn4-xGax (x=0-0.75), and CeNiAl4-xInx (x=0-0.25) solid solutions are isotypic to CeNiAl4, a known intermediate valent (IV) material. We present the lattice parameters and temperature dependences of the Seebeck coefficients for a range of alloys from each of these solid solutions. In several cases, including CeNi0.75Co0.25Al4 and CeNiGaIn3, the thermopowers of these alloys are significantly higher than those for the parent compounds (x=0). We also report strong evidence for stacking faults in single crystals of some of these materials.