Magnetic and Mössbauer investigations of soft Co2Z-type hexa nanoferrites

Abstract

Co2Z-type hexa nanoferrites of the series Ba3-XSrXCo2Fe24O41 (where x = 0, 0.5, 1.0, 1.5 and 2.0) are synthesized by sol-gel auto combustion method. The effects of Sr2+ substitution for Ba2+ and optimized synthesis conditions are reported using the structural, magnetic and Mössbauer study. The X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) along with the selected area electron diffraction (SAED) clearly indicate the formation of a single-phased Z-type hexagonal nanoferrites with P63/mmc space group. The hysteresis curves obtained by vibrating sample magnetometer (VSM) at room temperature displayed the typical characteristics of magnetically soft materials indicating the decrease in coercivity with the increase in Sr2+ concentration in synthesized hexa nanoferrites, which are validated by the room temperature Mössbauer spectra with least-squares fit sextets of six distinguishable sites (A: 4fIV, B: 4fIV*, C: 12kVI*, D: 4fVI* + 4eIV, E: 12kVI and F: 2dV + 2aVI + 4fVI + 4eVI). Selection of Sr2+ dopant and sol-gel auto combustion soft chemical route are the leading ways to control the coercivity of Co2Z-type hexa nanoferrites.