Phases and their Relations in the BaO(BaCO₃)-CaO-CuO System

Abstract

Phases and their relations in the BaO(BaCO₃)-CaO-CuO system at 900°C in air have been studied by XRD. The formation of two types of copper oxycarbonates were newly formed: one is a phase with a composition of Ba:Ca:Cu=0.600:0.080:0.320 and the other is a solid solution formed in a region of the compositional triangle of (Ba:Ca:Cu)=(0.666:0:0.333)-(0.650:0.017:0.333)-(0.650:0.070:0.280). The crystal structures of these phases have been determined by XRD, TEM and ED. These copper oxide carbonates commonly have tetragonal structures with a≈√2a_p and c≈2a_p. Unfortunately, no diamagnetic response was observed for the new two copper oxycarbonates.