Effect of temperature on magnetic properties of BaYxFe12−xO19 hexaferrites

Abstract Yttrium doped barium hexaferrites with chemical composition BaYxFe12−xO19 (0.0≤x≤1.0) were synthesized by facile ceramic route. The effect of the yttrium ion concentration on the temperature-dependent magnetic properties of the BaYxFe12−xO19 hexaferrites (0.0≤x≤1.0) has been investigated in the temperature range of 10–300 K and magnetic field of 50 kOe. The structural, morphological, compositional and magnetic properties of the products were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM) techniques, respectively. XRD patterns demonstrated pure, single phase hexagonal crystal. The average crystallite size of the samples varies in the range of 47–63 nm. SEM images indicated hexagonal platelet-like particles. EDX measurements confirmed the expected formula of BaYFe11O19 hexaferrite. It has been observed that the preferential site occupancy of the nonmagnetic yttrium ions strongly changes the magnetic properties. The saturation magnetization value close to the bulk one was measured as 62.62 and 88.21 emu/g for 300 and 10 K, respectively. It has been found from the magnetization measurements that the saturation magnetization reaches its maximum value at x=0.4 and then decreases with further increasing of the concentration (x). As the temperature goes up, the saturation magnetization decreases due to the weakening of superexchange interaction. The coercive field increases by about three times with increasing of the concentration from x=0.0 to 1.0 due to an increasing of anisotropy field and reaches the maximum value of 3556 Oe at x=1.0.