Influence of annealing time on the magnetic properties of La0.8Sr0.2CoO3 compound

For the La1-xSrxCoO3 compounds with x less than or equal to 0.3, the format ion of homogenous samples appear to depend strictly on the preparation cond itions that cause the electronic and magnetic data reported scatter strongl y. In the present contribution, the results of systematic investigation of the influence of annealing time (t(a)) on various magnetic parameters are r eported for the x = 0.2 substance, i.e. near the percolation threshold betw een spin-glass and cluster-glass phases. High Sr-concentration phases are i nitially formed at short t(a) but gradually transformed to lower Sr-concent ration ones with longer t(a). This transformation process apparently finish es at t(a) approximate to 200 h and homogenous samples with the purely expe cted stoichiometric phase can be obtained with longer t(a). The results fro m transport measurements are also mentioned in comparison to the magnetic d ata. (C) 2001 Elsevier Science B.V. All rights reserved.