Studies Of Nano-ferrite Powders Synthesizing By Hydrothermal Stripping

Nano-powders of NiFe₂O₄,MgFe₂O₄ and their adulterants of Lanthanun have been synthesized by hydrothermal stripping from metal-loaded organic phase,and some factors influencing hydrothermal stripping were investigated.Iron, Nickel, Magnesium and Lanthanun-loaded organic phases were prepared by conventional extraction technology with naphthenic acid-sooctyl alcohol, respectively. Based on the metal extraction rates in organic phase at different conditions, the appropriate experimental conditions which prepared the metal-loaded organic phase were obtained.The powders of NiFe₂O₄,NiLaxFe₂-xO₄,MgFe₂O₄ and MgLaxFe₂-xO₄ were synthesized by stripping the metals in metal-loaded organic phase mixed with water. The effects of stripping temperature and constituent of aqueous phase, such as pure water, acid, alkali, salt and surfactant on powders were investigated.According to the characterization of structure and morphology obtained by X-ray powder diffraction patterns and TEM images, the powders of NiFe₂O₄ and MgFe₂O₄ synthesized by hydrothermal stripping technique were the typical spinel ferrite with well crystallized and nano-particles. The experimental results reveal that the powders stripping by pure water are small and homogenous particles shaped in quasi- sphere and without obvious agglomeration (the average granularity of NiFe₂O₄ was about 7nm and MgFe₂O₄ was about 18nm). The stripping temperature has an obvious effect on granularity, and was controlled the range 180²300C.The magnetism of powders was investigated, and the preliminary experimental results show that compared adulterant with ferrite, the specific saturation magnetization (Bs) depressed, and the remanence (Br) and coercive force (Hc) increased.