Electrical Resistivity and Magnetic Susceptibility Measurements on Copper Arsenides

Electrical resistivity (4.2–800°K) and magnetic susceptibility (4.2–500°K) measurements are carried out on Cu 3–x As, Cu 5–x As 2 and the recently obtained, tetragonal Cu 2 As. All three compounds appear to be metallic conductors, but have high residual resistances because of the large defect concentrations (resulting from non‐stoichiometry and preparation method). Cu 3–x As is diamagnetic; Cu 5–x As 2 is Pauli‐paramagnetic; Cu 2 As has a very small, constant, positive susceptibility above room temperature and a more pronounced Curie‐Weiss behaviour at lower temperatures. The Pauli‐paramagnetic contributions have been estimated. A slight anomaly in the electric and magnetic behaviour of Cu 3–x As is observed at 220°K. To clarify the high‐temperature phenomena, a series of D.T.A. and X‐ray experiments has also been carried out.