Study On Magnetism Properties Of ZnFe₂O₄Crystals Prepared By Hydrothermal Method

In this paper, Fe-doped zinc oxide crystal and by-products of zinc ferrite were prepared by hydrothermal method,using3mol/L KOH as mineralizer,filling degree is35%, temperature is430℃.ZnO had been doped both FeCl2·4H2O、SnCl2·2H2O ompound and FeCl2·4H2O、 In2O3compound. Based on the measurement and analysis of their properties,ZnO doped of Fe、Sn completely with six corners of sheet structure.The results of SQUID shows that the ferromagnetism is very weak for ZnO, but mainly is superparamagnetic.Although the magnetic moment of ZnO decreases as the temperature increases in M-T curve, the total magnetic moment is very weak.The magenetism, microstructure and composition of the by-products of ZnFe2O4were characterized by SQUID, Scanning electron microscopy(SEM) and X-ray diffraction(XRD).The results indicated that ZnFe2O4has a spinel phase and nice microncrystal structure,as well as smooth surface, the integrity of the structure. Meanwhile,the results of SQUID indicated that ZnFe2O4has a high magnetic moment that reached50emu/g when T=2K, H=50000Oe, including magnetic moment began to decline tinily after125K on M-T curves.Zinc ferrite micron crystals of spinel structure is prepared by hydrothermal method,5mol/L and8mol/L KOH and8mol/L NaOH as mineralizer respectively, filling degree is65%, temperature is430℃,24hours as the reaction temperature. The magenetism, microstructure and composition of the ZnFe2O4were also characterized by SQUID, Scanning electron microscopy(SEM) and X-ray diffraction(XRD).The results indicated that ZnFe2O4has a inverse spinel phase and nice octahedron structure,as well as smooth surface.The size of zinc ferrite crystal is larger than by-products of zinc ferrite more or less8μm. Specially several crystal were20μm among zinc ferrite prepared when8mol/L NaOH as mineralizer.The results of SQUID indicated that ZnFe2O4is ferromagnetic at300K both KOH and NaOH as mineralizer.Especially,high saturation magnetization of93emu/g at300K and coercivity of75(Oe) for the ferromagnetic Zinc ferrite crystal when NaOH as mineralizer.