A special thermal modeling tool, CrysVUn, which was developed by Crystal Growth Laboratory (CGL) of Fraunhofer Institute of Integrated Systems and Devices Technology in Erlangen of Germany, was used for numerical anal...A special thermal modeling tool, CrysVUn, which was developed by Crystal Growth Laboratory (CGL) of Fraunhofer Institute of Integrated Systems and Devices Technology in Erlangen of Germany, was used for numerical analysis of growth interface situation. The heat transportation, argon flow and melt convection have been considered. Cauchy's first and second laws of motion have been the governing partial equations for stress calculation. The measurement results and simulation results were compared and the interface shape and thermal stress distribution during 300 mm Czochralski (CZ) silicon crystal growth with different growth rates were predicted.展开更多
The morphology and microstructure of flow pattern defects (FPDs) in lightly boron-doped Czochralski-grown silicon (Cz-Si) crystals were investigated using optical microscopy and atomic force microscopy. The experiment...The morphology and microstructure of flow pattern defects (FPDs) in lightly boron-doped Czochralski-grown silicon (Cz-Si) crystals were investigated using optical microscopy and atomic force microscopy. The experimental results showed that the morphology of FPDs was parabola-like with several steps. Single-type and dual-type voids were found on the tip of FPDs and two heaves exist on the left and right sides of the void. All the results have proved that FPDs were void-type defects. These results are very useful to investigate FPDs in Cz-Si wafers further and explain the annihilation of FPDs during high-temperature annealing.展开更多
The method used is divided into two parts. One part is the determination of La, Ce, Pr and Sm by pretreatment neutron activation analysis. The other part is the determination of Ce, Eu, Tb, Tm, Yb and Lu by direct ins...The method used is divided into two parts. One part is the determination of La, Ce, Pr and Sm by pretreatment neutron activation analysis. The other part is the determination of Ce, Eu, Tb, Tm, Yb and Lu by direct instrument neutron activation analysis. Pretreatment of samples was carried out by P<sub>507</sub> extraction chromatography. The decontamination factor of Y was 2×10<sup>4</sup>. A sensitive method for determination of REE in high-pure Y<sub>2</sub>O<sub>3</sub> was established.展开更多
The relation between the tempering effects of sinterd SmCo^(5)alloy at 750℃and its intrinsic coercivity(i^(Hc))has been studied by the use of photoelectron energy spectrum.X-ray diffraction and high-voltage electron ...The relation between the tempering effects of sinterd SmCo^(5)alloy at 750℃and its intrinsic coercivity(i^(Hc))has been studied by the use of photoelectron energy spectrum.X-ray diffraction and high-voltage electron microscope.The result is that the cause of iHc dropping seriously for sintered SmCo_(5)alloy tempered at 750 t is not the eutectoid decomposition of SmCo_(5)and the increase of oxygen.In fact,iHcdropping is caused by that some defect-rich regions in Sm_(2)Co_(17)decomposed form SmC0_(5)from nucleation centers in reversed magnetization course.展开更多
The magnetic properties of (Nd_(0.9)Dy_(0.1))_(16)Co_(5)Fe_(70)Nb_(2)B_(7) permanent magnetic alloy prepared by powder metallurgy are:Br=1.08T,_(1)H_(C)=1620kA/m,(BH)_(max)=208kJ/m^(3).The behaviour of Nb in this allo...The magnetic properties of (Nd_(0.9)Dy_(0.1))_(16)Co_(5)Fe_(70)Nb_(2)B_(7) permanent magnetic alloy prepared by powder metallurgy are:Br=1.08T,_(1)H_(C)=1620kA/m,(BH)_(max)=208kJ/m^(3).The behaviour of Nb in this alloy was studied by joint methods of dynamic observation by high voltage electron microscope(HVEM)and Mossbauer effects.With Nb and Co substituting parts of Fe and adding a little Dy,practical magnetic alloy with excellent properties can be obtained.The thermal stability of it is 80 ℃ higher than that of ternary Nd-Fe-13 magnet.The study shows that adding Nb into Nd-Fe-B can make the intrinsic coercivity appear peak value at about Nb=2%(in mole fraction).Nb mainly enters into Nd-rich and B-rich phases,a little into Nd_(2)Fe_(14)B phase.展开更多
Nd（OH）3 particles sized of nanometer have been prepared using the different methods. The obtained neodymium hydroxide samples were investigated using the enhanced electronic Raman spectroscopy, X-ray diffraction, tr...Nd（OH）3 particles sized of nanometer have been prepared using the different methods. The obtained neodymium hydroxide samples were investigated using the enhanced electronic Raman spectroscopy, X-ray diffraction, transmission electron microscopy, as well as field emission electron microscopy. Observable changes in electronic Raman bands were found among the electronic Raman spectra of Nd（OH）3 particles which formed under different physical-chemical conditions. Compared to the difference of the X-ray diffraction paterns, it suggests that the change of size and morphology of Nd（OH）3 particles occurs with subtle variation on the coordination environment around the neodymium ions, while the X-ray diffraction indicates the different long-ranged ordered structure of the Nd（OH）3 particles. Furthermore, the selected area electron diffraction （SAED）, which manifests several crystal cells orientation, shows that the obtained Nd（OH）3 particles are of the same hexagonal symmetry of Nd（OH）3. Therefore, the X-ray diffraction, selected area electron diffraction （SAED） and enhanced electronic Raman spectroscopy reflect different levels of structure of neodymium hydroxide in morphological, crystalline, and coordination environment. At certain extent, the subtle variation of coordination structure may account for the special physical-chemical properties of nanometer materials. The enhanced electronic Raman spectroscopy could be a new probe to study the subtle variation of the physical-chemical properties of nanometer materials.展开更多
Cuprous oxide micro-/nanocrystals were synthesized by using a simple liquid phase reduction process under microwave irradiation.Copper sulfate was used as the starting materials and macromolecule surfactants served as...Cuprous oxide micro-/nanocrystals were synthesized by using a simple liquid phase reduction process under microwave irradiation.Copper sulfate was used as the starting materials and macromolecule surfactants served as the templates.The morphologies phase and optical properties of them are characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflection absorptive spectra (UV-vis/DRS),respectively.The crystals had four different shapes,namely spheres,strips,octahedrons,and dandelions.The photocatalytic behavior of the cuprous oxide particles were investigated by monitoring the degradation of rhodamine B.In spite of the different morphologies,all of the cuprous oxide micro-/nanocrystals exhibited photocatalytic activities under visible light irradiation in the following order:dandelions,strips,spheres,and octahedral crystals.The photocatalytic degradation rates of rhodamine B are 56.37%,55.68%,51.83% and 46.16%,respectively.The morphology affects significantly the photocatalytic performance.展开更多
基金the International Scientific and Technical Corporation Major Planning Project (No. 2005DFA5105).
文摘A special thermal modeling tool, CrysVUn, which was developed by Crystal Growth Laboratory (CGL) of Fraunhofer Institute of Integrated Systems and Devices Technology in Erlangen of Germany, was used for numerical analysis of growth interface situation. The heat transportation, argon flow and melt convection have been considered. Cauchy's first and second laws of motion have been the governing partial equations for stress calculation. The measurement results and simulation results were compared and the interface shape and thermal stress distribution during 300 mm Czochralski (CZ) silicon crystal growth with different growth rates were predicted.
文摘The morphology and microstructure of flow pattern defects (FPDs) in lightly boron-doped Czochralski-grown silicon (Cz-Si) crystals were investigated using optical microscopy and atomic force microscopy. The experimental results showed that the morphology of FPDs was parabola-like with several steps. Single-type and dual-type voids were found on the tip of FPDs and two heaves exist on the left and right sides of the void. All the results have proved that FPDs were void-type defects. These results are very useful to investigate FPDs in Cz-Si wafers further and explain the annihilation of FPDs during high-temperature annealing.
文摘The method used is divided into two parts. One part is the determination of La, Ce, Pr and Sm by pretreatment neutron activation analysis. The other part is the determination of Ce, Eu, Tb, Tm, Yb and Lu by direct instrument neutron activation analysis. Pretreatment of samples was carried out by P<sub>507</sub> extraction chromatography. The decontamination factor of Y was 2×10<sup>4</sup>. A sensitive method for determination of REE in high-pure Y<sub>2</sub>O<sub>3</sub> was established.
文摘The relation between the tempering effects of sinterd SmCo^(5)alloy at 750℃and its intrinsic coercivity(i^(Hc))has been studied by the use of photoelectron energy spectrum.X-ray diffraction and high-voltage electron microscope.The result is that the cause of iHc dropping seriously for sintered SmCo_(5)alloy tempered at 750 t is not the eutectoid decomposition of SmCo_(5)and the increase of oxygen.In fact,iHcdropping is caused by that some defect-rich regions in Sm_(2)Co_(17)decomposed form SmC0_(5)from nucleation centers in reversed magnetization course.
基金Supported by the State Key Laboratory of Magnetism,Chinese Academy of Sciences。
文摘The magnetic properties of (Nd_(0.9)Dy_(0.1))_(16)Co_(5)Fe_(70)Nb_(2)B_(7) permanent magnetic alloy prepared by powder metallurgy are:Br=1.08T,_(1)H_(C)=1620kA/m,(BH)_(max)=208kJ/m^(3).The behaviour of Nb in this alloy was studied by joint methods of dynamic observation by high voltage electron microscope(HVEM)and Mossbauer effects.With Nb and Co substituting parts of Fe and adding a little Dy,practical magnetic alloy with excellent properties can be obtained.The thermal stability of it is 80 ℃ higher than that of ternary Nd-Fe-13 magnet.The study shows that adding Nb into Nd-Fe-B can make the intrinsic coercivity appear peak value at about Nb=2%(in mole fraction).Nb mainly enters into Nd-rich and B-rich phases,a little into Nd_(2)Fe_(14)B phase.
文摘Nd（OH）3 particles sized of nanometer have been prepared using the different methods. The obtained neodymium hydroxide samples were investigated using the enhanced electronic Raman spectroscopy, X-ray diffraction, transmission electron microscopy, as well as field emission electron microscopy. Observable changes in electronic Raman bands were found among the electronic Raman spectra of Nd（OH）3 particles which formed under different physical-chemical conditions. Compared to the difference of the X-ray diffraction paterns, it suggests that the change of size and morphology of Nd（OH）3 particles occurs with subtle variation on the coordination environment around the neodymium ions, while the X-ray diffraction indicates the different long-ranged ordered structure of the Nd（OH）3 particles. Furthermore, the selected area electron diffraction （SAED）, which manifests several crystal cells orientation, shows that the obtained Nd（OH）3 particles are of the same hexagonal symmetry of Nd（OH）3. Therefore, the X-ray diffraction, selected area electron diffraction （SAED） and enhanced electronic Raman spectroscopy reflect different levels of structure of neodymium hydroxide in morphological, crystalline, and coordination environment. At certain extent, the subtle variation of coordination structure may account for the special physical-chemical properties of nanometer materials. The enhanced electronic Raman spectroscopy could be a new probe to study the subtle variation of the physical-chemical properties of nanometer materials.
基金supported by the Open Foundation of National Laboratory of Mineral Materials of China University of Geosciences (Grant No. 08A006)the Key Project of Chinese Ministry of Education (No. 107023)+1 种基金Special Fund of Co-construction of Beijing Education CommitteeCity University of Hong Kong Strategic Research Grant (SRG) No. 7008009
文摘Cuprous oxide micro-/nanocrystals were synthesized by using a simple liquid phase reduction process under microwave irradiation.Copper sulfate was used as the starting materials and macromolecule surfactants served as the templates.The morphologies phase and optical properties of them are characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflection absorptive spectra (UV-vis/DRS),respectively.The crystals had four different shapes,namely spheres,strips,octahedrons,and dandelions.The photocatalytic behavior of the cuprous oxide particles were investigated by monitoring the degradation of rhodamine B.In spite of the different morphologies,all of the cuprous oxide micro-/nanocrystals exhibited photocatalytic activities under visible light irradiation in the following order:dandelions,strips,spheres,and octahedral crystals.The photocatalytic degradation rates of rhodamine B are 56.37%,55.68%,51.83% and 46.16%,respectively.The morphology affects significantly the photocatalytic performance.
