Structure and magnetic properties of Ba1−xDyxFe12−yZnyO19 synthesized by Sol–Gel auto-combustion technique

Abstract Ba1-xDyxFe12-yZnyO19 (x ​= ​0–0.1 and y ​= ​0–1) hexaferrites were produced by the sol-gel auto-combustion technique. In the XRD analyses of all samples, BaFe12O19 phase was observed as the pure state. ZnFe2O4 begins to form at x ​= ​0.02 and y ​= ​0.2 and peak intensities increases with the substution of Dy3+ and Zn2+ cations for the samples sintered at 900 ​°C and 1100 ​°C. As the temperature increases to 1300 ​°C, peaks belonging to BaFe12O19 phase were disappeared and transformed into Ba3Fe26O41 and BaZn1.2Fe16.8O27 phases at x ​= ​0.06 and y ​= ​0.6. Crystallite size decreased with increasing Dy3+ and Zn2+ substitutions for the samples sintered at 900 ​°C and 1100 ​°C. The smallest crystallite size obtained at 900 ​°C, x ​= ​0.06 and y ​= ​0.6. As the amount of substitution elements increase, saturation magnetization (Ms) and remenance magnetization (Mr) values decreased due to the formation of paramagnetic spinel ZnFe2O4 phase for the samples sintered at 900 ​°C and 1100 ​°C. The highest Mr value of 36.1 emu/g was obtained for the pure samples sintered at 1300 ​°C. It decreased sharply to 18.9 emu/g (about 50%) with the substitution of Dy3+ and Zn2+ cations at x ​= ​0.02 and y ​= ​0.2. Dy3+ and Zn2+ substituted hexaferrites sintered at 900 ​°C (x ​= ​0.06 and y ​= ​0.6) exhibited the highest Hc value of 4.84 ​kOe.