Magnetic phase study of Sr-doped LaCoO alloys by using neutron diffraction

Recent interests in strontium-doped lanthanum-cobalt oxides, LaSrCoO, have been motivated by their advanced high electrical and excellent ionic conductivity properties. These features make them good candidate materials for electrodes in fuel cells and ferroelectric memory devices where their practical applications have been hindered by technical difficulties such as fatigue and imprint. Polycrystalline La1-xSrxCoO3 (x = 0.15, 0.25 and 0.30) bulk samples were prepared by using the standard solid-state reaction. The structural properties of the samples were characterized by using X-ray diffraction and X-ray photoemission spectroscopy. By measuring the temperature dependence of the inverse magnetic susceptibility, the Curie temperatures were determined to be 147, 217, and 232 K for x = 0.15, 0.25, and 0.30 samples, respectively. The zero-field cooled magnetization measurements revealed a spin-glass like behavior for x = 0.15. Interestingly, the neutron diffraction data demonstrated little hint of an antiferromagnetic phase at low temperatures, which requires a more advanced magnetic model, including the spin state of Co, to elucidate the spin-glass behavior at low Sr concentrations.