Influence of Cr and Zn substitution on structural, magnetic and dielectric properties of Sr2-xZnxNi2Fe28-yCryO46 X-type hexagonal ferrite

Polycrystalline materials of Sr2-xZnxNi2Fe28-yCryO46 (x = 0.00, 0.01, 0.02, 0.03 and 0.04; y = 0.0, 0.2, 0.4, 0.6 and 0.8) X-type nano-ferrites are fabricated by sol-gel synthetic route. The TGA results of the prepared samples showed that these materials have high thermal stability. The analysis of x-ray diffraction patterns is confirmed X-type phase of these materials. The crystallite size was under 50 nm for all samples, which confirmed that these materials lie in nano-scale range. The large value of dielectric constant (91, 123) and moderate loss (0.52, 0.92) of Sr1.98Zn0.02Ni2Fe27.60Cr0.4O46 and Sr1.97Zn0.03Ni2Fe27.40Cr0.6O46 samples respectively were observed. Slope versus concentration graph indicated that the ac conductivity of all the exhibited frequency dependent behavior. Cole-Cole plots exhibited complete semicircle for these materials, which showed the grain boundary resistance inside the samples. The magnetic properties such that saturation, remanent magnetization (M-s,M- M-r), squareness ratio (M-r/M-s), coercivity (H-c), anisotropy constant (K) and magnetic moment are examined from hysteresis loops. The saturation magnetization was increased (45.42-52.45 emu/g) while the coercivity was decreased (414-630 Oe) by substitution of Cr3+-Zn2+. The increase in magnetic moment from 21.08 mu(B) to 24.34 mu(B) was observed by inclusion of Cr3+-Zn2+. The multi domain nature was evidenced by the smaller squareness ratio (0.36-0.40) of these ferrites. The high saturation magnetization and small coercivity of Sr1.98Zn0.02Ni2Fe27.60Cr0.4O46, Sr1.97Zn0.03Ni2Fe27.40Cr0.6O46 samples was obtained up to 52.45 emu/g, 49.42 emu/g and 345 Oe, 448 Oe respectively, which show their applications for absorption of electromagnetic radiation at microwave region and development of multilayer chip inductors. The dielectric properties of Sr1.98Zn0.02Ni2Fe27.60Cr0.4O46 and Sr1.97Zn0.03Ni2Fe27.40Cr0.6O46 ferrites showed that these materials might be consider for the development of super-capacitor devices.