Low Temperature Hydrothermal Method And Molten Salt Method Synthesis Of Magnetic Powders And Its Characterization

The introduction of nano-scale ferrite powders was made in the thesis, mainly reviewing such preparing methods as hydrothermal process and molten salt route. Spinel ferrite and SrBi2Nb2O9 powders have successfully been synthesized by the hydrothermal process and/or molten salt method, and characterized by using a transmission electron microscope (TEM) and X-ray diffractometer (XRD), and viberating sample magnetometer (VSM). And the processing conditions which affect crystallizing characters including the particle size and morphology were also investigated. The results showed that the pH value of initial precursor solutions, volume ratio of (CH3)2CHOH /water (RH), heating temperature and holding time had different influence on the formation of spinel ferrite crystallites in the hydrothermal process,where the possible formation mechanism of spinel ferrite crystallites was initially established. The preparing process could be optimized by adjusting above processing conditions.Flake-like NiFe2O4 powders were successfully prepared by the molten salt method for the first time. In addition, the crystallization and development of the product have been also studied in the thesis, on the base of the discussion of processing conditions like salt species, calcining temperature and holding time. The resultant NiFe2O4 powders were characterized by means of TEM and XRD, and VSM which was used to measure magnetic property.Another product with Flake-like particle morphology, SrBi2Nb2O9 powders, was successfully synthesized by the molten salt method. The processing conditions have been discussed in detail, where the effects of the presence or absence of the salt medium, calcining temperature and holding time on the formation of SrBi2Nb2O9 crystallites were investigated. Finally, the optimized processing condition was...