Structural and magnetic properties of hexaferrite Ba_0.5Ca_0.5Mn₂Fe₈Ti₄O₁₉

Full text: The term ferrites is used to refer to all magnetic oxides containing iron as a major metallic component. They have contributed greatly to technological applications because of their room temperature ferromagnetic and insulating properties. Ferrites with hexagonal structures, called hexaferrites, which have long been utilized in permanent magnets and microwave devices, can be classified into different types such as M, W, X, Y, U, and Z. Their crystal structures can be described as stacked sequences of the basic blocks: S, R, and T. Very recently, giant magnetoelectric effects have been reported in some hexaferrites, in which the electric polarization (P) can be induced by the application of a magnetic field. Comprehensive research of the synthesis process by high temperature solid-state reaction method, the crystal structure characterization, and the magnetic properties in the pure-phase multiferroic compound Ba_0.5Ca_0.5Mn₂Fe₈Ti₄O₁₉ have been undertaken. Crystal structure characterization performed by X-ray Diffraction measurements and Rietveld analysis, allowed proving that material crystallizes in a M-type hexaferrite on the hexagonal-like structure, belonging to the P63/mmc (Z=2) space group. The surface morphological and microstructure characterization carried out by Scanning Electron Microscopy (SEM) and Semi-quantitative compositional study, performed by Energy-Dispersive X-ray (EDX) experiments, corroborated that M-type hexaferrite in crystallographic pure-phase Ba_0.5Ca_0.5Mn₂Fe₈Ti₄O₁₉ was correctly obtained. Results of magnetization M as a function of applied magnetic field H, in recipes ZFC and FC, presents large magnetization at room temperature, and shows the existence of ferromagnetic-like behavior. (author)