ESR studies of magnetic clusters in Li1-xNi1+xO2

A brief account is given of the resolution of Bloch's equation in order to have access to the frequency of precession of the magnetisation of a parama gnetic system or a ferromagnetic one with axial symmetry. These results are used to understand the magnetic properties of several compounds of the Li1 -xNi1+xO2 family with x = 0.02, 0.07 and 0.14, using electron spin resonanc e measurements. The compound with x = 0.02 is shown to have a paramagnetic behaviour, while the compound with x = 0.14 orders ferromagnetically below 150 K, Both types of behaviour are observed in the compound with x = 0.07. These results are discussed in terms of magnetic cluster formation in these compounds. (C) 2000 Elsevier Science B.V. All rights reserved.