Chapter 207 Structure-property relations of ternary equiatomic YbTX intermetallics

Abstract

The equiatomic intermetallic compounds RTX (R = rare earth or actinide metal; T = transition metal; X = element of the 3rd or 4th main group) have attracted considerable interest in the last two decades due to their greatly varying physical properties. The various magnetic properties strongly depend on the energy of the uranium 5f electrons with respect to the Fermi level as well as the strength of hybridization of the uranium 5f states with the conduction electrons. Within the series of rare-earth RTX compounds those with cerium, europium, and ytterbium display the largest variety of physical properties. The chapter focuses on the ytterbium-based compounds. Besides mixed valency (Yb 2+ or Yb 3+ ), these ytterbium intermetallics can also display heavy-fermion or Kondolike behavior. Structural phase transitions accompanied by a valence change (Yb 3+ in the low-temperature and Yb 2+ in the high-temperature modification) have recently been observed for α- and β-YbPdSn and α- and β-YbAgGa 2 , while stable trivalent ytterbium occurs in the ZrNiAl-type compounds YbNiAl and YbPtSn, which order antiferromagnetically below T N = 2.9 and 3.5 K, respectively.