Improvement of the multiferroic properties of lanthanum ferrites through cobalt doping

LaFeO3 is a second-type multiferroic material, characterized by an improper ferroelectricity, which is induced by the magnetic order of the material. However, it shows antiferromagnetic order which limits their applications. In order to induce ferromagnetism, in the present work is studied the effects of Co2+ doping in LaCoxFe1-xO3, with x varying from 0 to 0.5, Δx=0.1 on the crystal structure, magnetic and dielectric properties. Moreover, it is described the mechanism responsible for the ferromagnetism in doped ferrites. The XRD results show that at doping levels lower than 0.3 mol, LaFeO3 maintains its orthorhombic structure (Pnma), whereas at higher cobalt concentrations, the rhombohedral (R3c) LaCoO3 phase emerges. In addition, it is observed that cobalt doping induces ferromagnetism as a consequence of the cobalt occupying iron positions until the solubility limit is reached and the formation of Fe doped LaCoO3. All samples present high relative permittivity values, which increase with cobalt content. Furthermore, the presence of cobalt leads to a reduction in the dielectric dissipation factor, attributed to decreased crystal structure distortion.