The crystal structure, heat capacity (1.5–80 K) and magnetic susceptibility (1.6–300 K) of LaAgGe and CeAgGe

Abstract The crystal structures of the new ternary germanides LaAgGe and CeAgGe were determined from X-ray powder diffractometry data. These compounds crystallize in a new type of superstructure related to the CaIn2-type structure which is characterized by an ordered distribution of the smaller atoms (silver and germanium) in the unit cell and a lower symmetry: space group P63mc instead of P6/mmc. The heat capacity (1.5–80 K), magnetic susceptibility (1.6–300 K) and electric resistivity (4.2–35 K) were measured. CeAgGe orders antiferromagnetically below 4.8 K, and has an electronic specific heat coefficient of 15.7 mJ mol(Ce)−1 K−2 which is typical of normal intermetallic compounds. LaAgGe exhibits an extremely low value of electronic specific heat coefficient (0.18 mJ (g-atom)−1 K−2) which is about four times smaller than that of pure copper. The large residual electrical resistivity, 1250 μΩ cm, suggests that it is a semimetal or a dirty semiconductor, but the possibility that this large value may be due to microcracks and voids cannot be ruled out.