| In this paper, a series of nanosize Mn1-xZnxFe2O4(x=0,0.2,0.4,0.6,0.8,1.0) particles were fabricated by hydrothermal method using Fe2(SO4)3 ,ZnSO4 and MnSO4 as material, among them rare earth(RE=La,Ce,Nd)were doped.First, we groped the synthesizing conditions of MnFe2O4,ZnFe2O4 and characterized them by XRD,TEM and IR.The results showed that ethonal washing deposit can lighten agglomeration;Mn2+ is easizer than Zn2+ to form perfect spinel ferrite, MnFe2O4 is more unstable and has stronger surfacial absorption,and both were superparamagnetic.Secondly, in compound Mn1-xZnxFe2O4, the influences of pH,reacting temperature and time, and raw material on Mn0.6Zn0.4Fe2O4 were discussed,and it was characterized by XRD,TEM,IR ,VSM,TG-DTA and DSC.The results showed that the ideal pH is around 10,rising temperature is more favorable to crystal growing than prolonging reacting time;the growth of crystal can be controlled by adding organic group(-COO-); Mn-Zn ferrite with –OH is very stable; its magnetic loop presents supermagnetic behavior and its curie point(Tc) is 320℃. The lattice of nanosize Mn1-xZnxFe2O4 decreases with x increasing,and its value deviated the therotical lattice(α0) of normal size Mn-Zn ferrites. Saturation magnetization(Bs) of nanosize MnxZn1-xFe2O4 has a extremum at x=0.4～0.5 .Finally, rare earth(RE=La,Ce,Nd) doping Mn-Zn ferrites were characterized by XRD,SEM,TEM,TG-DTA,DSC and VSM ,and the influence of doping element on Mn0.6Zn0.4Fe2O4 structure and magnetic properties was discussed. The result indicated that the content of doped element should not exceed 0.1; Saturation magnetization(Bs) of rare earth doping Mn-Zn ferrite is obviously bigger than that of pure Mn-Zn ferrite;The magnetic properties of La3+,Ce3+ and Nd3+ doping Mn-Zn ferrites changing trends with rare earth content(x) are similar and their curie point (Tc) is above 300℃.
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