Synthesis and magnetic properties of the quasi-one-dimensional compound Ca 0.83(Cu 1− xCo x)O 2

Abstract

A new solid solution of the quasi-one-dimensional composite crystal, Ca 0.83( Cu 1−x Co x) O 2 (0⩽x⩽0.30) , has been synthesized under 1 atm of O 2 at 830°C. The non-doped compound Ca 0.83CuO 2 consists of two interpenetrating monoclinic subsystems of the [Ca] atoms and the edge-shared square planar [CuO 2] chains. Upon increasing x, both the subsystems undergo a phase change from monoclinic to orthorhombic ( M– O). The M– O change occurs at x∼0.04 for the [(Cu,Co)O 2] subsystem, while such a change occurs at x∼0.17 for the [Ca] subsystem. Magnetic susceptibility measurements show an evolution from a short-range ordered state near x=0 to a long-range antiferromagnetic state (T N =10–15 K) for the samples with x⩾0.15. The effective magnetic moment μ eff is found to increase with increasing x from 2.1 μ B for x=0.10 to 3.0 μ B for x=0.30, suggesting that the solid solution can be regarded as Ca 0.83[Cu 0.66 2+Cu 0.34− x 3+Co x 3+]O 2, in which a mixed state of Cu 2+( S=1/2), Cu 3+( S=0) and high-spin Co 3+( S=2) ions is realized.