Some magnetic and crystallographic properties of the system Li+xNi++1−2xni+++xO

Crystallographic and magnetic measurements of the system Li+xNi++1−2xNi+++xO for the entire range 0 ⩽ x ⩽ 0.5 are reported. For values ofx ⩽ 0.3, the lattice appears to be antiferro-magnetic and is cubic above the Curie temperature. For the range of compositions 0.3 < x < 0.5, the lattice is rhombohedral and ferrimagnetic, a maximum magnetic moment pet gram of 31 c.g.s. cm3g being observed at x = 0.46. A maximum ferrimagnetic Curie temperature of 241°K was observed for the composition x = 0.41. These properties are interpreted in terms of a partial ordering of lithium and nickel ions into alternate sets of (111) planes which couple antiparallel to one another, the moments within any set being either ferromagnetically coupled or paramagnetic, depending upon the number of non-magnetic near neighbors in the neighboring planes. This system is compared to the ordered rock-salt-type compound Cu0.25Co0.75O. The lack of ferrimagnetism and the tetragonal distortion to c/a < 1 in Cu0.25Co0.75O are explained.