A new ternary compound YbZn2As2 with mixed valency of Yb

A new compound with chemical formula YbZn2As2 and 'anti'-La2O3-type crystal structure (space group P3m1) has been synthesized for the first time. The trigonal lattice constants of the compound are a=0.4157 and c=0.6954 nm. In the temperature range 77-500 K, the magnetic susceptibility of YbZn2As2 fo llows the Curie-Weiss law, indicating antiferromagnetic interactions of the Yb ions and yielding a Curie temperature theta=-52.8 K and an effective ma gnetic moment mu(eff)=2.35 mu(B) (the Bohr magneton) per Yb ion. This means that a part of the Yb ions has valency 3+, instead of 2+ for all the Yb io ns, as would be expected from their formal oxidation number, i.e. YbZn2As2 is a compound with mixed valency of Yb. YbZn2As2 exhibits p-type conductivi ty with a room temperature electrical resistivity of 0.15 Omega cm which de creases when lowering temperature and reaches a practically constant value of 0.08 Omega cm below 20 K. (C) 1999 Elsevier Science S.A. All rights rese rved.