Double-doping Effect on Structural and Magnetic Properties of Perovskite Lanthanum Manganite

Abstract

Polycrystalline samples La(2+4x)/3Sr(1–4x)/3Mn1−xCuxO3 (x = 0, 0.1, 0.15 and 0.25) with double doping in the A site and B site were successfully prepared by the conventional solid-state reaction method with heat treatment up to 1300 °C. All the obtained samples consist of single perovskite phase with a rhombohedral symmetry and R 3 ¯ C space group. The (a) lattice parameter and the volume of the unit cell were found to increase with the increase of Cu doping level (x). The morphology of the prepared samples was studied by scanning electron microscope imaging, and the stoichiometry of the compositions was confirmed. The hysteresis loops at room temperature for x = 0, 0.1 and 0.15 samples are characteristic for soft ferromagnetic materials, with a decrease of the ferromagnetic interaction and a decrease of the magnetic moment with the increase of Cu doping level. No ferromagnetic behavior was detected at room temperature for the x = 0.25 sample. The question of the valency of Cu ions was discussed during the present study. Our results are best interpreted by assuming the coexistence of Cu2+ and Cu3+ ions.