Description of Anhydrous (Black) Dioptase as a S = 1/2 Uniform Antiferromagnetic Chain System

Abstract

AbstractThe structural and magnetic properties of anhydrous (black) dioptase, CuSiO3, were investigated by carrying out single‐crystal X‐ray diffraction, specific heat, and magnetic susceptibility measurements as well as by performing spin dimer analysis based on extended Hückel tight‐binding calculations. Our spin dimer analysis indicates that black dioptase is a S = 1/2 uniform antiferromagnetic chain system with the interchain spin exchange weaker than the intrachain exchange by three orders of magnitude. Specific heat and magnetic susceptibility measurements show that the intrachain exchange is –174(2) K, and the interchain exchange is of the order of ~2 K. They lead to long‐range magnetic ordering at about 5 K as evidenced by a broad anomaly in the specific heat.