Influence of Mg and Ni substitution on structural, microstructural and magnetic properties of Sr2Co2−xMgx/2Nix/2Fe12O22 (Co2Y) hexaferrite

• Synthesis of ultrafine Y-type hexaferrite particle via sol–gel auto combustion method.
• Effect of Ni and Mg ions on magnetic and structural properties of Sr2CO2−xMgx/2Nix/2Fe12O22 hexaferrite is investigated.
• The coercivity decreased at low doping content x=0.15.
• Average thickness of particle has been decrease from 100 to 50 nm by the increase of Mg and Ni ions.

In this study, Mg and Ni substituted Y-type hexaferrite particles with narrow size distribution have been prepared by using a sol–gel auto combustion method. The effects on structural, microstructure and magnetic properties have been investigated by substituting Mg2+ and Ni2+ at Co2+ sites. XRD patterns showed that Y-type hexaferrite phase formation has not been affected by substituting magnesium and nickel with cobalt in the range of 0.0≤x≤0.75. Various parameters such as lattice constants, cell volume and crystallite size have been calculated based on XRD data. The morphology and size distribution of the particles have been studied using high resolution field emission scanning electron microscopy (FESEM). It was also understood that the average crystallite size of particles increased from 45 to 63 nm with an increase of x content at Co2Y compound. Magnetic properties were determined using a vibrating sample magnetometer (VSM). The magnetic results revealed that by increasing the Mg and Ni in octahedral and tetrahedral sites, the coercivity was also increased from 949 to 1066 Oe, whereas saturation magnetization and Remnant magnetization were decreased from 47.98 to 40.78 emu/g and 23.05 to 20.99 emu/g, respectively.