Abstract
Neutron diffraction and small-angle scattering on La1 − xSrxCoO3 (0 < x ⩽ 0.30) show that for x = 0.3 the system is near a two-phase percolation threshold and undergoes a transition from itinerant to polaronic conduction at the Curie temperature TC. The stabilization of superparamagnetic clusters on warming through TC is revealed by an anomalous thermal expansion of the volume and a deviation of the paramagnetic susceptibility from the Curie-Weiss law. The development of a temperature-dependent small-angle-scattering signal confirms that regions of short-range ferromagnetic order are present above TC.