In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying....In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying. The discharge capacity of the fast cooled was 83 mAh·g-1 and the slow cooled 121 mAh·g-1. The particle size of the synthesized powder was examined by transmission electron microscopy and distribution of Fe2P was characterized using scanning electron microscopy (SEM). In addition, two-step heat treatment was carried out for better distribution of Fe2P. X-ray diffraction (XRD) and Rietveld refinement reveal that LiFePO4/Fe2P composite consists of 95.77% LiFePO4 and 4.33% of Fe2P.展开更多
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 novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^（3＋） composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by tr...A novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^（3＋） composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe^（3＋） composite was obtained by aqueous mixing of carbon dots and FeCl_3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe^（3＋） cations, resulting in the low fluorescence intensity of the carbon dots/Fe^（3＋） composite. On the other hand, H_2PO_4^- reduced the concentration of Fe^（3＋） by chemical reaction and enhanced the fluorescence of the carbon dots/Fe^（3＋） composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe^（3＋） composite and the concentration of H_2PO_4^-, and a fine linearity（R2=0.997） was found in the range of H_2PO_4^- concentration of 0.4-12 m M.展开更多
以磷铁废渣(Fe1.5P)和温室效应气体CO_2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO_4)的前驱体Fe_2P_2O_7,并研究了其合成过程对LiFePO_4正极材料储能性能的影响。采用SEM观察了LiFePO_4的表面形貌,采用XRD分析了LiFePO_4和Fe_2P_2O_...以磷铁废渣(Fe1.5P)和温室效应气体CO_2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO_4)的前驱体Fe_2P_2O_7,并研究了其合成过程对LiFePO_4正极材料储能性能的影响。采用SEM观察了LiFePO_4的表面形貌,采用XRD分析了LiFePO_4和Fe_2P_2O_7的晶体结构。进一步对该方法进行优化,发现Fe1.5P与磷酸混合物(nFe1.5P∶nH3PO4=1∶1)在800℃热处理6 h合成的Fe_2P_2O_7对应的LiFePO_4/C电化学性能最好,在0.1C,0.2C,0.5C和1C倍率下的容量分别可达130,126,117和108 m Ah·g^(-1)。展开更多
利用Fe_2P_2O_7和碳酸锂为原材料,并通过不同的碳包覆合成LiFePO_4/C复合材料.利用XRD、SEM、碳硫分析仪、恒流充放电法和循环伏安对产物的组成、结构、形貌和电化学性能进行测试,确定含碳量为2.45wt%的LiFePO_4/C复合材料具有更好的电...利用Fe_2P_2O_7和碳酸锂为原材料,并通过不同的碳包覆合成LiFePO_4/C复合材料.利用XRD、SEM、碳硫分析仪、恒流充放电法和循环伏安对产物的组成、结构、形貌和电化学性能进行测试,确定含碳量为2.45wt%的LiFePO_4/C复合材料具有更好的电化学性能.实验结果表明,在0.1C倍率下,锂离子电池的放电比容量为130.49 m Ah/g,在1C倍率下,锂离子电池的放电比容量为108.58 m Ah/g.展开更多
A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced: Fe2O3(+NH4H2PO4)→Fe2P2O7(+Li2CO3+glucose)→LiFePO4/C.X-ray diffractometry(XRD),Fourier transform infrared ...A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced: Fe2O3(+NH4H2PO4)→Fe2P2O7(+Li2CO3+glucose)→LiFePO4/C.X-ray diffractometry(XRD),Fourier transform infrared spectroscopy(FTIR)and scanning electron microscopy(SEM)were utilized to characterize relevant products obtained in the synthetic procedure.The reaction of Fe2P2O7 and Li2CO3 was investigated by thermo-gravimetric and differential thermal analysis(TGA-DTA).Fe2O3 is completely reduced to Fe2P2O7 by NH4H2PO4 at 700 °C and Fe2P2O7 fully reacts with Li2CO3 to form LiFePO4 in the temperature range of 663.4-890 °C.The primary particles of LiFePO4/C samples prepared at 670,700 and 750 °C respectively exhibit uniform morphology and narrow size distribution,0.5-3 μm for those obtained at 670 and 700 °C and 0.5-5 μm for those obtained at 750 °C.LiFePO4/C(carbon content of 5.49%,mass fraction)made at 670 °C shows an appreciable average capacity of 153.2 mA·h/g at 0.1C in the first 50 cycles.展开更多
文摘In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying. The discharge capacity of the fast cooled was 83 mAh·g-1 and the slow cooled 121 mAh·g-1. The particle size of the synthesized powder was examined by transmission electron microscopy and distribution of Fe2P was characterized using scanning electron microscopy (SEM). In addition, two-step heat treatment was carried out for better distribution of Fe2P. X-ray diffraction (XRD) and Rietveld refinement reveal that LiFePO4/Fe2P composite consists of 95.77% LiFePO4 and 4.33% of Fe2P.
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supported by the Fund for Young Scientists of Sichuan University, China (2011SCU11081)Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20120181120103)~~
基金Funded by the National Natural Science Foundation of China(Nos.61575150 and 61377092)the Natural Science Foundation of Hubei Province(N0.2014CFB831)
文摘A novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^（3＋） composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe^（3＋） composite was obtained by aqueous mixing of carbon dots and FeCl_3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe^（3＋） cations, resulting in the low fluorescence intensity of the carbon dots/Fe^（3＋） composite. On the other hand, H_2PO_4^- reduced the concentration of Fe^（3＋） by chemical reaction and enhanced the fluorescence of the carbon dots/Fe^（3＋） composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe^（3＋） composite and the concentration of H_2PO_4^-, and a fine linearity（R2=0.997） was found in the range of H_2PO_4^- concentration of 0.4-12 m M.
基金financially supported by the National Science Foundation of China (Grant No.21576170)the Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan province (Grant No.2017CL19)~~
文摘以磷铁废渣(Fe1.5P)和温室效应气体CO_2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO_4)的前驱体Fe_2P_2O_7,并研究了其合成过程对LiFePO_4正极材料储能性能的影响。采用SEM观察了LiFePO_4的表面形貌,采用XRD分析了LiFePO_4和Fe_2P_2O_7的晶体结构。进一步对该方法进行优化,发现Fe1.5P与磷酸混合物(nFe1.5P∶nH3PO4=1∶1)在800℃热处理6 h合成的Fe_2P_2O_7对应的LiFePO_4/C电化学性能最好,在0.1C,0.2C,0.5C和1C倍率下的容量分别可达130,126,117和108 m Ah·g^(-1)。
文摘利用Fe_2P_2O_7和碳酸锂为原材料,并通过不同的碳包覆合成LiFePO_4/C复合材料.利用XRD、SEM、碳硫分析仪、恒流充放电法和循环伏安对产物的组成、结构、形貌和电化学性能进行测试,确定含碳量为2.45wt%的LiFePO_4/C复合材料具有更好的电化学性能.实验结果表明,在0.1C倍率下,锂离子电池的放电比容量为130.49 m Ah/g,在1C倍率下,锂离子电池的放电比容量为108.58 m Ah/g.
基金Project(2010ZC051)supported by the Natural Science Foundation of Yunnan Province,ChinaProject(2009-041)supported by Analysis and Testing Foundation from Kunming University of Science and Technology,ChinaProject(14118245)supported by the Starting Research Fund from Kunming University of Science and Technology,China
文摘A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced: Fe2O3(+NH4H2PO4)→Fe2P2O7(+Li2CO3+glucose)→LiFePO4/C.X-ray diffractometry(XRD),Fourier transform infrared spectroscopy(FTIR)and scanning electron microscopy(SEM)were utilized to characterize relevant products obtained in the synthetic procedure.The reaction of Fe2P2O7 and Li2CO3 was investigated by thermo-gravimetric and differential thermal analysis(TGA-DTA).Fe2O3 is completely reduced to Fe2P2O7 by NH4H2PO4 at 700 °C and Fe2P2O7 fully reacts with Li2CO3 to form LiFePO4 in the temperature range of 663.4-890 °C.The primary particles of LiFePO4/C samples prepared at 670,700 and 750 °C respectively exhibit uniform morphology and narrow size distribution,0.5-3 μm for those obtained at 670 and 700 °C and 0.5-5 μm for those obtained at 750 °C.LiFePO4/C(carbon content of 5.49%,mass fraction)made at 670 °C shows an appreciable average capacity of 153.2 mA·h/g at 0.1C in the first 50 cycles.
