以V_2O_5、C_(12)H_(22)O_(11)和AgNO_3为原料,采用水热法制备Ag掺杂VO_2(B)正极材料,通过XRD、FESEM、XPS、EDS、循环伏安(CV)、交流阻抗(EIS)等表征手段,研究掺Ag对VO_2(B)的结构、形貌及电化学性能的变化规律。结果表明,当掺杂量为0....以V_2O_5、C_(12)H_(22)O_(11)和AgNO_3为原料,采用水热法制备Ag掺杂VO_2(B)正极材料,通过XRD、FESEM、XPS、EDS、循环伏安(CV)、交流阻抗(EIS)等表征手段,研究掺Ag对VO_2(B)的结构、形貌及电化学性能的变化规律。结果表明,当掺杂量为0.43%(atom)时,样品(Ag_1)首次放电比容量为340.5 m A·h·g^(-1),较未掺杂样品(Ag_0)提高了80.5%。当掺杂量为1.28%(atom)时,样品(Ag_3)表现出最好的循环稳定性,首次放电容量为213.6 m A·h·g^(-1),100次循环后,容量保持率为58.3%。展开更多
The VO2 powders were prepared by hydrothermal synthesis.The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied.The XRD,SEM and TEM results show that...The VO2 powders were prepared by hydrothermal synthesis.The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied.The XRD,SEM and TEM results show that the heat treatment temperature has a significant effect on the crystal transformation of VO2 precursor.Increasing temperature is conducive to the transformation of precursor VO2(B)to ultrafine VO2(M).The Y-doping affects the structure of VO2.Y^3+can occupy the lattice position of V4+to form YVO4 solid solution,which can increase the cell parameters of VO2.Due to the lattice deformation caused by Y-doping,the aggregation of particles is prevented,and the grain is refined obviously.DSC curves show that Y-doping can reduce the phase transition temperature of VO2(M).After adding 9 at.%Y,the phase transition temperature can be reduced from 68.3 to 61.3℃.展开更多
Raman spectra of a vanadoborate （Na3VO2B6Oll） crystal from room temperature up to the melting point have been recorded. The main internal vibrational modes of the crystal have been assigned. It was found that all th...Raman spectra of a vanadoborate （Na3VO2B6Oll） crystal from room temperature up to the melting point have been recorded. The main internal vibrational modes of the crystal have been assigned. It was found that all the Raman bands exhibit decreases in frequency and the widths of the Raman bands increase with the increase of temperature. However, no phase transition was observed under 525 ℃. The micro-structure of its melt was studied by quantum chemistry ab initio calculation. The continuous three-dimensional network of the crystal collapsed and transformed into VO4 and VBO6 clusters during the melting process with an isomerization reaction from four-coordinated boron to a three-coordinated species.展开更多
TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM...TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.展开更多
文摘以V_2O_5、C_(12)H_(22)O_(11)和AgNO_3为原料,采用水热法制备Ag掺杂VO_2(B)正极材料,通过XRD、FESEM、XPS、EDS、循环伏安(CV)、交流阻抗(EIS)等表征手段,研究掺Ag对VO_2(B)的结构、形貌及电化学性能的变化规律。结果表明,当掺杂量为0.43%(atom)时,样品(Ag_1)首次放电比容量为340.5 m A·h·g^(-1),较未掺杂样品(Ag_0)提高了80.5%。当掺杂量为1.28%(atom)时,样品(Ag_3)表现出最好的循环稳定性,首次放电容量为213.6 m A·h·g^(-1),100次循环后,容量保持率为58.3%。
基金Projects(51404183,51504177)supported by the National Natural Science Foundation of China。
文摘The VO2 powders were prepared by hydrothermal synthesis.The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied.The XRD,SEM and TEM results show that the heat treatment temperature has a significant effect on the crystal transformation of VO2 precursor.Increasing temperature is conducive to the transformation of precursor VO2(B)to ultrafine VO2(M).The Y-doping affects the structure of VO2.Y^3+can occupy the lattice position of V4+to form YVO4 solid solution,which can increase the cell parameters of VO2.Due to the lattice deformation caused by Y-doping,the aggregation of particles is prevented,and the grain is refined obviously.DSC curves show that Y-doping can reduce the phase transition temperature of VO2(M).After adding 9 at.%Y,the phase transition temperature can be reduced from 68.3 to 61.3℃.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51302268 and 51102239)the Natural Science Foundation of Anhui Province,China(Grant No.KJ2015A339)
文摘Raman spectra of a vanadoborate （Na3VO2B6Oll） crystal from room temperature up to the melting point have been recorded. The main internal vibrational modes of the crystal have been assigned. It was found that all the Raman bands exhibit decreases in frequency and the widths of the Raman bands increase with the increase of temperature. However, no phase transition was observed under 525 ℃. The micro-structure of its melt was studied by quantum chemistry ab initio calculation. The continuous three-dimensional network of the crystal collapsed and transformed into VO4 and VBO6 clusters during the melting process with an isomerization reaction from four-coordinated boron to a three-coordinated species.
文摘TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.
