| Material is one of the three pillars of the development of modern society.With the development of the science and technology,functional materials,especially magnetic materials have played a more and more important role in the fields of industrial technology,computer technology,health and medicine and artificial intelligence.As the result of the higher requirements of miniaturization,intelligence and versatility of the devices by the application of these technologies,so it has brought up more advanced standards on the materials performance,and that brings greater challenges for the synthesized processes of the materials.In this paper,we had successfully synthesized the spinel cobalt and nickel ferrite nanoparticles under the optimized process conditions:metallic salt solution concentration was 0.3 M(mole per liter),precipitant concentration was 3 M,nitrogen concentration was 0.5 M,pH = 11.8×0.02(12.8×0.02),SDBS dispersant concentration was 0.5 g/L,bath temperature was 50℃,stirring velocity was 300 rpm,salt solution velocity was 0.5 ml/min and the reaction time lasted for 10 h,which were determined by the research of the major influence factors of the coprecipitation process,and we had also explored the effects of various calcination temperatures on the samples’magneto-electric properties.The phase,morphology and magneto-electric properties were characterized by X-ray diffractometer,laser particle size analyzer,vibrating sample magnetometer,precise impedance analyzer and scanning electron microscope.The results showed that the samples calcined at a temperature lower than 500℃ for 2 h started to form pure phase powder and achieved a high degree of crystallinity at 800℃calcination temperature.The hysteresis loop of CoFe2O4 sample calcined at 500℃ for 2 h was obtained by VSM.And its saturation magnetization,coercivity and residual magnetization which were the best were 14.66 emu/g,40.4 Oc and 3.13 cmu/g,respectively.Besides,here there appeared a turning point for the magnetic properties of the CoFe2O4 sample calcined at this temperature.The hysteresis loop of the NiFe2O4 sample calcined at 800℃ for 2 h was also measured by the same method with Ms ＝27.03 emu/g,coercivity He = 30.41 Oe and remanent Mr = 7.00 emu/g.What’s more,the permeability and dielectric properties of their ceramics sintering at 1100℃ for 2 h were further characterized.The thin films of CoFe2O4 and NiFe2O4 deposited on SrTiO3 substrate were acquired by pulsed laser deposition means utilizing their pure phase ceramics as targets.And the surface morphology of the thin films was characterized by atomic force microscope,the results showed that the quality of the thin films prepared at 700℃deposition temperature was the best.Furthermore,the non-magnetic spinel oxides of MgAl2O4 and ZnAl2O4 nanoparticles had been synthesized likewise by coprecipitation method,and the precursor powders formed pure phases with a relatively high crystallinity annealed at 900℃ for 2 h,their grain sizes were about 10 nm and 20 nm,respectively,calculated by scherrer equation. |
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