The structure ofV2O5-P2O5-Sb2O3-Bi2O3glass and its state of crystallization were studied by means of infrared spectroscopy and X-ray diffraction analysis. The results indicate that, in this glass, V and P exist mainly...The structure ofV2O5-P2O5-Sb2O3-Bi2O3glass and its state of crystallization were studied by means of infrared spectroscopy and X-ray diffraction analysis. The results indicate that, in this glass, V and P exist mainly in the form of a single-stranded linear （VO3）n and an isolated （PO4） tetrahedral with no double bond. Partial V and P are connected through O, forming an amorphous structure of layered vana- dium phosphate. Trivalent Sb3＋ and Bi3＋ open the V=O bond and appear in interlayers, so a weak three-dimensional structure is connected successfully. Along with the substitution of Sb203 for partial V205 or that of P205 for partial V205, the network structure of the glass is rein- forced, and the crystallization is reduced.展开更多
Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray d...Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron micro- scope （FESEM）, energy-dispersive spectroscopy （EDS）, and transmission electron microscopy （TEM）. The XRD and TEM results suggest that both the pristine and the coated materials have a hexagonal layered structure, and the FePO4 coating layer does not make any major change in the crystal structure. The FePO4-coated sample exhibits both improved initial discharge capacity and columbic efficiency compared to the pristine one. More significantly, the FePO4 coating layer has a much positive influence on the cycling perfor- mance. The FePO4-coated sample exhibits capacity reten- tion of 82 % after 100 cycles at 0.5℃ between 2.0 and 4.8 V, while only 28 % for the pristine one at the same charge-discharge condition. The electrochemical impe- dance spectroscopy （EIS） results indicate that this improved cycling performance could be ascribed to the presence of FePO4 on the surface of Li[Li0.2Ni0.13Co0.13Mno.54102 par- ticle, which helps to protect the cathode from chemical attacks by HF and thus suppresses the large increase in charge transfer resistance.展开更多
The crystal structure and magnetic properties of SmFeg_xCox （x = 0, 1, 3, 5） alloys were studied by X-ray powder diffraction （XRD） and magnetic measurements. The Th2Znl7-type structure of the as-cast state is chan...The crystal structure and magnetic properties of SmFeg_xCox （x = 0, 1, 3, 5） alloys were studied by X-ray powder diffraction （XRD） and magnetic measurements. The Th2Znl7-type structure of the as-cast state is changed to TbCu7-type structure after quenching to a rotating molybdenum roll under certain velocity （12, 20, and 32 m.s-l）. The （002） XRD peak appears and ^-Fe phase disappears when the Co is added up to x = 5. Saturation magnetization of SmFe9 under different temperature shows 9 % change （112-102 A.m2.g-1） when the temperature is higher than 200 K. The saturation magnetization is 115 A.m2.g-1 and coercivity is 0.304 T at 5 K for SmFe9 alloys. Increased saturation magnetization and decreased coercivity can be obtained for Co added up to x = 5 at 5 K.展开更多
文摘The structure ofV2O5-P2O5-Sb2O3-Bi2O3glass and its state of crystallization were studied by means of infrared spectroscopy and X-ray diffraction analysis. The results indicate that, in this glass, V and P exist mainly in the form of a single-stranded linear （VO3）n and an isolated （PO4） tetrahedral with no double bond. Partial V and P are connected through O, forming an amorphous structure of layered vana- dium phosphate. Trivalent Sb3＋ and Bi3＋ open the V=O bond and appear in interlayers, so a weak three-dimensional structure is connected successfully. Along with the substitution of Sb203 for partial V205 or that of P205 for partial V205, the network structure of the glass is rein- forced, and the crystallization is reduced.
基金financially supported by the National Nature Science Foundation of China (No.51302017)the National High Technology Research and Development Program of China (No.2012AA110102)the fund from the Science and Technology Commission of Beijing (No.2121100006712002)
文摘Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron micro- scope （FESEM）, energy-dispersive spectroscopy （EDS）, and transmission electron microscopy （TEM）. The XRD and TEM results suggest that both the pristine and the coated materials have a hexagonal layered structure, and the FePO4 coating layer does not make any major change in the crystal structure. The FePO4-coated sample exhibits both improved initial discharge capacity and columbic efficiency compared to the pristine one. More significantly, the FePO4 coating layer has a much positive influence on the cycling perfor- mance. The FePO4-coated sample exhibits capacity reten- tion of 82 % after 100 cycles at 0.5℃ between 2.0 and 4.8 V, while only 28 % for the pristine one at the same charge-discharge condition. The electrochemical impe- dance spectroscopy （EIS） results indicate that this improved cycling performance could be ascribed to the presence of FePO4 on the surface of Li[Li0.2Ni0.13Co0.13Mno.54102 par- ticle, which helps to protect the cathode from chemical attacks by HF and thus suppresses the large increase in charge transfer resistance.
基金financially supported by the National High Technology Research and Development Program of China(No.2011AA03A402)the International Scientific and Technological Cooperation Projects(No.2010DFB53520)
文摘The crystal structure and magnetic properties of SmFeg_xCox （x = 0, 1, 3, 5） alloys were studied by X-ray powder diffraction （XRD） and magnetic measurements. The Th2Znl7-type structure of the as-cast state is changed to TbCu7-type structure after quenching to a rotating molybdenum roll under certain velocity （12, 20, and 32 m.s-l）. The （002） XRD peak appears and ^-Fe phase disappears when the Co is added up to x = 5. Saturation magnetization of SmFe9 under different temperature shows 9 % change （112-102 A.m2.g-1） when the temperature is higher than 200 K. The saturation magnetization is 115 A.m2.g-1 and coercivity is 0.304 T at 5 K for SmFe9 alloys. Increased saturation magnetization and decreased coercivity can be obtained for Co added up to x = 5 at 5 K.
