The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were ch...The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investi-gated. The results revealed that the Fe3O4@SiO2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe3O4@SiO2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.展开更多
One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4（NZFO）/ Pb（Zr0.52Ti0.48）O3（PZT...One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4（NZFO）/ Pb（Zr0.52Ti0.48）O3（PZT） nanofibers with average diameters about 65 nm are prepared by electrospinning from poly（vinyl pyrrolidone） （PVP） and metal salts.The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy （FT- IR） ,X-ray diffraction （XRD）,scanning electron microscopy （SEM）.The magnetic properties for nanofibers are measured by vibrating sample magnetometer（VSM）.The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases,which are constructed from about 37 nm NZFO and 17 nm PZT grains.The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.展开更多
A Fe modified Na2WO4 compound was synthesized by a solution impregnation method and was ball-milled with MgH2 to constitute a novel MgH2-Fe2O3/Na2WO4 composite. The effects of the Fe2O3/Na2WO4 additive on the hydrogen...A Fe modified Na2WO4 compound was synthesized by a solution impregnation method and was ball-milled with MgH2 to constitute a novel MgH2-Fe2O3/Na2WO4 composite. The effects of the Fe2O3/Na2WO4 additive on the hydrogen storage properties of MgH2 together with the corresponding mechanism were investigated. At 423 K, within the first 200 seconds, the hydrogen absorption amount of MgH2+20 wt% Fe2O3/Na2WO4 was almost 5 times that of pure MgH2. And at 573 K, its total hydrogen desorption amount was 7 times that for pure MgH2. Meanwhile, its onset dehydrogenation temperature was 110 K lower than that of pure MgH2. It was worth noting that the MgH2+20 wt% Fe/Na2WO4 presented the lower dehydrogenation reaction activation energy(Ea) of 35.9 kJ·mol^-1 compared to that of pure MgH2. The active MgWO4, Mg2 FeH6 and MgO formed during the milling process were responsible for the improvement of the hydrogen storage properties for MgH2.展开更多
文摘The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investi-gated. The results revealed that the Fe3O4@SiO2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe3O4@SiO2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.
基金Funded by the National Natural Science Foundation of China (No. 50674048)Research Fund for the Doctoral Program of Higher Education of China(No.20103227110006)
文摘One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4（NZFO）/ Pb（Zr0.52Ti0.48）O3（PZT） nanofibers with average diameters about 65 nm are prepared by electrospinning from poly（vinyl pyrrolidone） （PVP） and metal salts.The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy （FT- IR） ,X-ray diffraction （XRD）,scanning electron microscopy （SEM）.The magnetic properties for nanofibers are measured by vibrating sample magnetometer（VSM）.The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases,which are constructed from about 37 nm NZFO and 17 nm PZT grains.The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.
基金Funded by the National Natural Science Foundation of China(No.51771164)Scientific Research Projects in Colleges and Universities in Hebei Province,China(No.ZD2019307)+2 种基金the Fundamental Research Funds for the Central Universities(No.3142019013)the Natural Science Foundation of Hebei Province of China(No.E2019508214)the Program for Top-notch Young Talents in University of Hebei Province(No.BJ2016043)
文摘A Fe modified Na2WO4 compound was synthesized by a solution impregnation method and was ball-milled with MgH2 to constitute a novel MgH2-Fe2O3/Na2WO4 composite. The effects of the Fe2O3/Na2WO4 additive on the hydrogen storage properties of MgH2 together with the corresponding mechanism were investigated. At 423 K, within the first 200 seconds, the hydrogen absorption amount of MgH2+20 wt% Fe2O3/Na2WO4 was almost 5 times that of pure MgH2. And at 573 K, its total hydrogen desorption amount was 7 times that for pure MgH2. Meanwhile, its onset dehydrogenation temperature was 110 K lower than that of pure MgH2. It was worth noting that the MgH2+20 wt% Fe/Na2WO4 presented the lower dehydrogenation reaction activation energy(Ea) of 35.9 kJ·mol^-1 compared to that of pure MgH2. The active MgWO4, Mg2 FeH6 and MgO formed during the milling process were responsible for the improvement of the hydrogen storage properties for MgH2.
