使用还原铁粉作为铁源,通过超细球磨与喷雾干燥、高温煅烧技术制备了球形微纳米LiFePO_4/C复合材料。使用DSC/TG以及XRD对LiFePO_4/C复合材料的形成过程进行了分析;使用SEM、穆斯堡谱仪等手段对复合材料进行分析;使用电化学工作站、容...使用还原铁粉作为铁源,通过超细球磨与喷雾干燥、高温煅烧技术制备了球形微纳米LiFePO_4/C复合材料。使用DSC/TG以及XRD对LiFePO_4/C复合材料的形成过程进行了分析;使用SEM、穆斯堡谱仪等手段对复合材料进行分析;使用电化学工作站、容量测试仪对其充放电行为进行分析。研究发现,使用该合成技术路线,在500～700℃下能够合成LiFePO_4/C复合材料。获得的LiFePO_4/C复合材料具有规则的球形外貌,平均尺寸4～5μm。该微米颗粒由200 nm左右细小颗粒组成,颗粒间具有纳米尺寸微孔。穆斯堡谱仪测试结果表明,复合材料中Fe处于＋2价的价态。复合材料在1C倍率下表现出稳定的充放电行为,平均比容量在156 m Ah/g,300次循环后,容量保持率为92.8%。该技术制备的LiFePO_4/C复合材料具有潜在的应用价值。展开更多
In this paper,the dependencies of Young's modulus and attenuation decrement on samarium sulfide polycrystals(SmS)under various annealing temperatures are studied by the piezoelectric ultrasonic composite oscillato...In this paper,the dependencies of Young's modulus and attenuation decrement on samarium sulfide polycrystals(SmS)under various annealing temperatures are studied by the piezoelectric ultrasonic composite oscillator technique at a frequency of 100 kHz in the temperature range of 80-300 K.A decrease in Young's modulus with an increase of the annealing temperature due to the texturing of the material was revealed.At the same time,attenuation peaks were observed at temperatures about 90 and 125 K,presumably due to Niblett-Wilks and Bordoni relaxations.展开更多
We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with...We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. This longitudinal quantum conductance staircase, Gxx, is revealed by the voltage applied to the Hall contacts, Vxy, to a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the variations of the Vxy voltage appear to exhibit the fractional forms of the quantum conductance staircase with the plateaus and steps that bring into correlation respectively with the odd and even fractional values.展开更多
Temperature dependence of elastic moduli , , and the latter for the piezo-active and non-piezo-active versions, have been measured in the interval of 4 - 180 K at 28 - 262 MHz in a CdSe: Cr2+ crystal. Anomalies below ...Temperature dependence of elastic moduli , , and the latter for the piezo-active and non-piezo-active versions, have been measured in the interval of 4 - 180 K at 28 - 262 MHz in a CdSe: Cr2+ crystal. Anomalies below 40 K have been found for all the moduli, except . The interpretation of the results has been carried out involving the Jahn-Teller effect and relaxation between the equivalent distortions of the tetrahedral CrSe4 centers.展开更多
A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samp...A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure to β-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes.展开更多
The continuous series of perovskite-related oxides with the general formula GdzSr（Al1-xFex）207 0 〈 x 〈 1 were prepared by conventional ceramic technology in air. The pro- cessing stages of Gd2Sr（Al1-xFex）207 0 ...The continuous series of perovskite-related oxides with the general formula GdzSr（Al1-xFex）207 0 〈 x 〈 1 were prepared by conventional ceramic technology in air. The pro- cessing stages of Gd2Sr（Al1-xFex）207 0 〈 x 〈 1 phases were investigated by means of X-ray powder diffraction （XRD） and scanning electron microscopy （SEM） with the element phase analysis. The three main stages of GdeSr（All_~Fex）aO7 for- marion are pointed out. The analysis of the mutual influence of intermediate compounds on the synthesis of the target solid solutions of complex composition, in particular for Gd2Sr（All-xFex）207 was carried out. It is determined that the closeness of the reactive mixture composition to the composition of individual compounds Gd2SrA1207 or GdaSrFeaO7 is of importance for the realization of a partic- ular way of GdESr（Al1-xFex）207 solid solutions formation. It is shown that at x ,= 0.2 the reversing in scheme of Gd2Sr（Al1-Fex）207 series formation is observed. The formation of the Gd2Sr（Al1-xFex）207 continuous series is indicated by the monotonic dependence of molar unit cell volume on the iron content x.展开更多
文摘使用还原铁粉作为铁源,通过超细球磨与喷雾干燥、高温煅烧技术制备了球形微纳米LiFePO_4/C复合材料。使用DSC/TG以及XRD对LiFePO_4/C复合材料的形成过程进行了分析;使用SEM、穆斯堡谱仪等手段对复合材料进行分析;使用电化学工作站、容量测试仪对其充放电行为进行分析。研究发现,使用该合成技术路线,在500～700℃下能够合成LiFePO_4/C复合材料。获得的LiFePO_4/C复合材料具有规则的球形外貌,平均尺寸4～5μm。该微米颗粒由200 nm左右细小颗粒组成,颗粒间具有纳米尺寸微孔。穆斯堡谱仪测试结果表明,复合材料中Fe处于＋2价的价态。复合材料在1C倍率下表现出稳定的充放电行为,平均比容量在156 m Ah/g,300次循环后,容量保持率为92.8%。该技术制备的LiFePO_4/C复合材料具有潜在的应用价值。
基金This research was supported by Russian Science Foundation under Grant 19-72-30004.
文摘In this paper,the dependencies of Young's modulus and attenuation decrement on samarium sulfide polycrystals(SmS)under various annealing temperatures are studied by the piezoelectric ultrasonic composite oscillator technique at a frequency of 100 kHz in the temperature range of 80-300 K.A decrease in Young's modulus with an increase of the annealing temperature due to the texturing of the material was revealed.At the same time,attenuation peaks were observed at temperatures about 90 and 125 K,presumably due to Niblett-Wilks and Bordoni relaxations.
文摘We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. This longitudinal quantum conductance staircase, Gxx, is revealed by the voltage applied to the Hall contacts, Vxy, to a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the variations of the Vxy voltage appear to exhibit the fractional forms of the quantum conductance staircase with the plateaus and steps that bring into correlation respectively with the odd and even fractional values.
文摘Temperature dependence of elastic moduli , , and the latter for the piezo-active and non-piezo-active versions, have been measured in the interval of 4 - 180 K at 28 - 262 MHz in a CdSe: Cr2+ crystal. Anomalies below 40 K have been found for all the moduli, except . The interpretation of the results has been carried out involving the Jahn-Teller effect and relaxation between the equivalent distortions of the tetrahedral CrSe4 centers.
文摘A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure to β-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes.
基金financially supported by the Russian Foundation for Basic Research(No.13-03-00,888)
文摘The continuous series of perovskite-related oxides with the general formula GdzSr（Al1-xFex）207 0 〈 x 〈 1 were prepared by conventional ceramic technology in air. The pro- cessing stages of Gd2Sr（Al1-xFex）207 0 〈 x 〈 1 phases were investigated by means of X-ray powder diffraction （XRD） and scanning electron microscopy （SEM） with the element phase analysis. The three main stages of GdeSr（All_~Fex）aO7 for- marion are pointed out. The analysis of the mutual influence of intermediate compounds on the synthesis of the target solid solutions of complex composition, in particular for Gd2Sr（All-xFex）207 was carried out. It is determined that the closeness of the reactive mixture composition to the composition of individual compounds Gd2SrA1207 or GdaSrFeaO7 is of importance for the realization of a partic- ular way of GdESr（Al1-xFex）207 solid solutions formation. It is shown that at x ,= 0.2 the reversing in scheme of Gd2Sr（Al1-Fex）207 series formation is observed. The formation of the Gd2Sr（Al1-xFex）207 continuous series is indicated by the monotonic dependence of molar unit cell volume on the iron content x.
