Structural and magnetic properties of strontium substituted NiZn ferrite nanopowders

Sr-substituted NiZn ferrite nanopowders, Ni0.5-xZn0.5SrxFe2.0O4 (0≤x≤0.20), were synthesized by the sol-gel auto-combustion method. The effects of Sr substitution on the structural and magnetic properties have been investigated. Differential thermal analysis-thermogravimetry (DTA-TG), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) measurements were used to characterize chemical, structural and magnetic properties. The DTA-TG results indicate that there are three steps of combustion process. XRD results indicate that the lattice parameter increases, and the average crystallite size decreases with increasing Sr substitution. The Sr2FeO4 and SrFe12O19 impurity phases formed with excess Sr substitution. The saturation magnetization monotonically decreases with the increase of Sr substitution. Meanwhile, the coercivity initially decreases with the increase of Sr substitution when x≤0.15, and increases when x>0.15.