Synthesis, Crystal Structure and Physical Properties of LixMg0.857-xCu2.143O3-y

Solid solutions of Li-doped Mg0.857Cu2.143O3 (LixMg0.857-xCu2.143O3-y) were prepared at 950°C for 12 h in air by the solid-state method using Li2CO3, MgO and CuO powders. The solid solutions were obtained as the single alpha phase with the güggenite structure in 0<,==x<, ==0.06 region. With the increasing of the Li content x, the lattice parameters a, b and unit cell volume V decreased, while c increased. On the basis of the charge neutrality, hole carrier estimated by the oxygen content increased with the Li substitution. The Seebeck coefficient at room temperature of x = 0.03 sample was +400 ~V/K. The electrical resistivity rhoat room temperature drastically decreased with the increasing x. Temperature dependences of rhofor x = 0.01, 0.03 and 0.06 samples were semi-conductive behavior from room temperature to about 12 K. Interaction between Cu2+ and Cu2+ through O2- seems to be somewhat large antiferromagnetic one. Sperconducting transition was not detected in the temperature range.