Synthesis, crystal structure and physical properties of LixMg0.857-xCu2.143O3-y

Solid solutions of Li-doped Mg0.857Cu2.143O3 (LixMg0.857-x Cu2.143O3-y) were prepared at 950degreesC 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 guggenite structure in 0 less than or equal to x less than or equal to 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 muV/K. The electrical resistivity p at room temperature drastically decreased with the increasing x. Temperature dependences of p for 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. (C) 2002 Elsevier Science (USA).