Dielectric, ferroelectric and magnetic study of iron doped hexagonal Ba4YMn3O11.5−δ (BYMO) and its dependence on temperature as well as frequency

Abstract

The effects of iron doping in Ba₄YMn₃O_11.5−δ (BYMO) on dielectric, ferroelectric and magnetic properties were studied. The Ba₄YMn_3−xFe_xO_11.5−δ (x = 0.05, 0.1, 0.2) are termed as BYMFO-05, BYMFO-1 and BYMFO-2, respectively. These samples were synthesized by a chemical route in which aqueous solutions of all the metal nitrates/acetates were used as starting materials. The synthesized materials were characterized by powder XRD, scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The Rietveld refinement confirms a hexagonal perovskite having the space group Rm. The particle size observed by TEM was found to be 7 nm. The remnant magnetization and remnant polarization increased with a decrease of temperature in all samples. The impedance spectroscopy reveals that the material has semiconducting grains and insulating grain boundaries which was also supported by an internal barrier layer capacitor model. The temperature and frequency dependent dielectric constant and the corresponding low dielectric loss indicate the material could be used for memory devices. A Debye type dielectric relaxation was observed only in the case of BYMFO-05, whereas temperature independent permittivity was observed in the cases of BYMFO-1 and BYMFO-2. The absence of a saturation in the magnetization as well as the ferroelectricity shows the lossy capacitor nature of the material.