Exploration of structural, optical, dielectric properties and curve fittings of Yb3+-substituted β-type hexagonal ferrites

Abstract

The rare-earth element Yb3+-substituted β-ferrites KFe11−xYbxO17 with composition (x = 0, 0.02, 0.06 and 0.1) have been synthesized by sol–gel auto combustion method and sintered at 950 °C. X-ray diffraction (XRD) analysis divulged the formation of single phase β-hexagonal ferrites structure for the whole series. The crystallite size varied in the range of 26–43 nm for all samples. FTIR spectra showed absorption bands at different wave numbers which also confirmed the single phase of the samples. The samples had high dielectric constant, dielectric loss, and tangent loss values at lower frequencies while these values declined with increase in frequency. This dielectric behavior of the samples had been explained on the basis of Maxwell–Wagner and Koop’s model. The dielectric constant results were fitted theoretically by using Debye function which indicated the involvement of more than one ion in dielectric relaxation process. The AC conductivity increased with the increase of frequency and the nonlinear fitting of AC conductivity was obtained through Jonscher’s power law that followed conduction model exactly. The semicircle of cole–cole plots adumbrated the contribution of both grains and grain boundaries to the resistive and capacitive behavior of the material.