The properties of La 2O 3 doped molybdenum powder were studied. The La 2O 3 nanoparticles on the surface of molybdenum powder which is produced by the reduction of La(NO 3) 3 doped MoO 2 in hydrogen decrease the inten...The properties of La 2O 3 doped molybdenum powder were studied. The La 2O 3 nanoparticles on the surface of molybdenum powder which is produced by the reduction of La(NO 3) 3 doped MoO 2 in hydrogen decrease the intensity of feature energy loss peak of molybdenum substrate; but increase that of peak of Mo?3d. The surface of molybdenum powder exposed to the atmosphere can be reduced because the surface is mainly covered with La 2O 3 nanoparticles. As a result, the capability of anti oxidation of molybdenum is improved.展开更多
采用光电子能谱分析方法对掺杂 L a2 O3的 Mo粉的性能进行了研究。结果表明 :掺杂 L a(NO3) 3的 Mo O2 粉经过还原处理后 ,Mo粉表面的纳米 L a2 O3微粒可以减小 Mo基体的特征能量损失峰 ,增加 Mo3d光电子谱峰强度 ;由于纳米 L a2 O3粒...采用光电子能谱分析方法对掺杂 L a2 O3的 Mo粉的性能进行了研究。结果表明 :掺杂 L a(NO3) 3的 Mo O2 粉经过还原处理后 ,Mo粉表面的纳米 L a2 O3微粒可以减小 Mo基体的特征能量损失峰 ,增加 Mo3d光电子谱峰强度 ;由于纳米 L a2 O3粒子在金属 Mo的表面及周围对 Mo起到包埋效应 ,减小了 Mo与大气的接触面积 ,从而使展开更多
The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic ...The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic process. The experimental results show that the rare earth doping can increase the aspect axial ratio of needle α-FeOOH grains. its anti-sintering capability during the heat-treatment and the thermostability of γ-Fe2O3 magnetic properties. The magnetic properties of γ-Fe2O3 doping with rare earth are as follows: the coercivity Hc=36.3 kA/m (445 Oe), the ratio saturation magnetization σs=90.4μWbm/kg (72 emu/g), the ratio remanent magnetization σr=54 μWbm/kg (43 emu/g), and the temperature coefficient of remanent magnetization of γ-Fe2O3 doping with 0.1 mol% Dy can reach -5 ×10-4℃-1.展开更多
The mechanical properties of molybdenum wires doped with different contents of La2O3 were investigated systematicaUy and the interaction between La2O3 particles with dislocations in Mo- La2O3 wires were observed by SE...The mechanical properties of molybdenum wires doped with different contents of La2O3 were investigated systematicaUy and the interaction between La2O3 particles with dislocations in Mo- La2O3 wires were observed by SEM and TEM. It is shown that Mo-La2O3 wires possess much higher tensile strength than the pure Mo. In wires the dislocation motion is strongly hindered by La2O3 particles, which remains up to much higher temperature. Moreover, a number of prismatic dislocation loops and hexagonal dislocation network have been formed in annealed Mo-La2O3 wires. The higher strength of Mo-LazOs than the pure Mo is attributed to the La2O3 particles dispersion strengthening and dislocation strengthening.展开更多
Infrared-to-visible upconverted luminescent spectra of Er3 t and La3 t codoped Y2O3 powders are investigated.By introducing La3 t ions, the upconversion green radiation is found to be greatly enhanced when compared wi...Infrared-to-visible upconverted luminescent spectra of Er3 t and La3 t codoped Y2O3 powders are investigated.By introducing La3 t ions, the upconversion green radiation is found to be greatly enhanced when compared with the powders with La3 t absent. Such enhancement can be attributed to the modification of the local symmetry surrounding the Er3 t ion, which benefits the intra-4f transitions of Er3 t ion, and the decreasing interaction between Er3 t ions, which suppresses the energy transfer process4F7∕2t 4I11∕2→ 4F9∕2t 4F9∕2.展开更多
The effects of La_2O_3 doping on the phase structure.electric properties and aging properties of the samples were researched using XRD,SEM and electric property measurements.The results suggest that the aging value of...The effects of La_2O_3 doping on the phase structure.electric properties and aging properties of the samples were researched using XRD,SEM and electric property measurements.The results suggest that the aging value of Mn_(2.38)Ni_(0.5)Cu_(0.12)O_4 thermistor ceramic samples decreases from 10%to about 6%by only doping La_2O_3.The electrical stability of the sample has improved as well.Such doped material will broaden the production and application scope of Cu contained negative temperature coefficient thermal ceramics.展开更多
In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that...In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for Eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.展开更多
文摘The properties of La 2O 3 doped molybdenum powder were studied. The La 2O 3 nanoparticles on the surface of molybdenum powder which is produced by the reduction of La(NO 3) 3 doped MoO 2 in hydrogen decrease the intensity of feature energy loss peak of molybdenum substrate; but increase that of peak of Mo?3d. The surface of molybdenum powder exposed to the atmosphere can be reduced because the surface is mainly covered with La 2O 3 nanoparticles. As a result, the capability of anti oxidation of molybdenum is improved.
文摘The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic process. The experimental results show that the rare earth doping can increase the aspect axial ratio of needle α-FeOOH grains. its anti-sintering capability during the heat-treatment and the thermostability of γ-Fe2O3 magnetic properties. The magnetic properties of γ-Fe2O3 doping with rare earth are as follows: the coercivity Hc=36.3 kA/m (445 Oe), the ratio saturation magnetization σs=90.4μWbm/kg (72 emu/g), the ratio remanent magnetization σr=54 μWbm/kg (43 emu/g), and the temperature coefficient of remanent magnetization of γ-Fe2O3 doping with 0.1 mol% Dy can reach -5 ×10-4℃-1.
基金supported by the National Key Basic Research and Development Programme of China(No.G1998061316)Beijing Science Star Foundation
文摘The mechanical properties of molybdenum wires doped with different contents of La2O3 were investigated systematicaUy and the interaction between La2O3 particles with dislocations in Mo- La2O3 wires were observed by SEM and TEM. It is shown that Mo-La2O3 wires possess much higher tensile strength than the pure Mo. In wires the dislocation motion is strongly hindered by La2O3 particles, which remains up to much higher temperature. Moreover, a number of prismatic dislocation loops and hexagonal dislocation network have been formed in annealed Mo-La2O3 wires. The higher strength of Mo-LazOs than the pure Mo is attributed to the La2O3 particles dispersion strengthening and dislocation strengthening.
基金financially supported by the Nature Science Foundation of Zhejiang Province under Grant No.LQ13F050003
文摘Infrared-to-visible upconverted luminescent spectra of Er3 t and La3 t codoped Y2O3 powders are investigated.By introducing La3 t ions, the upconversion green radiation is found to be greatly enhanced when compared with the powders with La3 t absent. Such enhancement can be attributed to the modification of the local symmetry surrounding the Er3 t ion, which benefits the intra-4f transitions of Er3 t ion, and the decreasing interaction between Er3 t ions, which suppresses the energy transfer process4F7∕2t 4I11∕2→ 4F9∕2t 4F9∕2.
文摘The effects of La_2O_3 doping on the phase structure.electric properties and aging properties of the samples were researched using XRD,SEM and electric property measurements.The results suggest that the aging value of Mn_(2.38)Ni_(0.5)Cu_(0.12)O_4 thermistor ceramic samples decreases from 10%to about 6%by only doping La_2O_3.The electrical stability of the sample has improved as well.Such doped material will broaden the production and application scope of Cu contained negative temperature coefficient thermal ceramics.
基金Project supported by the Polish Ministry of Science and Higher Education (NN 204331537)National Science Centre (N N507 372335)
文摘In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for Eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.
