Itinerant electron behaviour and long-range ordering in La1?x Sr x CoO3

Electrical resistivity of La_1?x Sr _x CoO₃ is reduced significantly by the substitution of Ni³⁺ ions in place of the cobalt ions. In the La_1?x Sr _x Co_1?y Ni _y O₃ system, for small values ofx(x=0·05) superparamagnetic clusters seem to be formed at lower temperatures (<300 K). The formation of such clusters is not affected by the presence of nickel ions. Whenx is large, the occurrence of long-range ordering seems to depend on the itinerancy of charge carriers.