Structural and magnetic properties of Nd-Mn substituted Y-type hexaferrites synthesized by microemulsion method

Nd-Mn substituted hexaferrites of composition Sr-2 xNdxNi0.5Co1.5Fe12 yMnyO22 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, y = 0.0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75) were synthesized using microemulsion method. The synthesized materials are characterized using different techniques including X-ray diffraction (XRD), scanning electron microscopy(SEM), atomic force microscopy (AFM), Fourier transform Infrared spectroscopy (FTIR), Inductance capacitance resistance (LCR) meter and Vibrating sample magnetic magnetometer (VSM). For all samples, a single Y-type phase was established and the lattice constants have been calculated. XRD patterns reveal the significant increase in line broadening which indicates a decrease of grain size. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. With the increasing substitution level of Nd-Mn, the average grain diameter decreases. The dielectric constant epsilon' and dielectric loss factor epsilon '' are found to decrease initially with an increase in frequency and reached a constant value at higher frequency, exhibiting a frequency-independent behavior at higher frequencies. The dielectric loss tangent tan delta was found to decrease with an increase in the frequency. The H-c decreases remarkably with increasing Nd and Mn ions content. It was found that the particle size could be effectively decreased and coercivity H-c could easily be controlled by varying the concentration (x) without significantly decreasing saturation magnetization. (C) 2014 Elsevier B. V. All rights reserved.