Magnetic and transport measurements on RAuAl (R=La, Ce, and Nd) compounds: Kondo-lattice behavior of CeAuAl

Structural transition and antiferromagnetic ordering in the solid solution CePd1−x Au x Al (x = 0.1–0.9)

The intermetallic solid solution CePd1−x Au x Al (x = 0.1–0.9) has been synthesized from the elements by arc-melting and subsequent annealing in induction followed by tube furnaces. The samples were characterized using the Guinier powder diffraction technique and the structures of the nominal compositions CeAuAl and CePd0.2Au0.8Al were refined from single crystal X-ray diffractometer data. For small values of x = 0.1–0.3, the compounds crystallize in the hexagonal ZrNiAl-type structure (space group P 6 ‾ $‾{6}$ 2m), while for x = 0.5–0.9 the orthorhombic TiNiSi-type structure (space group Pnma) was observed. In both structure types, the transition metal and aluminum atoms form a complex polyanionic network with the cerium atoms filling the respective cavities. The transition metal atoms are in both cases surrounded in the shape of a tri-capped trigonal prism, the connectivity of these units, however, is different. Temperature-dependent magnetic susceptibility measurements of all compounds indicated a stable trivalent oxidation state for the cerium atoms along with antiferromagnetic ordering around T N ∼ 3 K.

Cerium intermetallics with TiNiSi-type structure

Intermetallic compounds with the equiatomic composition CeTX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals (T) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these CeTX phases and on their physical properties, 119Sn and 121Sb Mössbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure–property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch. 2015, 70b, 289; Part II: Z. Naturforsch. 2015, 70b, 695; Part III: Z. Naturforsch. 2016, 71b, 165].