The investigation by SEM/TEM, porosity, and X-ray diffraction measurements of the graphitization process starting from amorphous carbon nanospheres, prepared by glucose carbonization, is reported. Aspects studied are ...The investigation by SEM/TEM, porosity, and X-ray diffraction measurements of the graphitization process starting from amorphous carbon nanospheres, prepared by glucose carbonization, is reported. Aspects studied are the annealing temperature in the 750–1000 °C range, the type of inert carrier gas, and time of treatment in the 2–6 h range. It is investigated how these parameters influence the structural and morphological characteristics of the carbon materials obtained as well as their nanostructure. It is shown that it is possible to maintain after graphitization the round-shaped macro morphology, a high surface area and porosity, and especially a large structural disorder in the graphitic layers stacking, with the presence of rather small ordered domains. These are characteristics interesting for various catalytic applications. The key in obtaining these characteristics is the thermal treatment in a flow of N2. It was demonstrated that the use of He rather than N2 does not allow obtaining the same results. The effect is attributed to the presence of traces of oxygen, enough to create the presence of oxygen functional groups on the surface temperatures higher than 750 °C, when graphitization occurs. These oxygen functional groups favor the graphitization process.展开更多
The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thermogravimetric analysis,X-ray diffraction measurement and pore structure analysis. T...The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thermogravimetric analysis,X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2,which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere,i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.展开更多
The diamond films adherent to Si substrate are deposited with the microwave plasma CVD(MPCVD) at microwave powers of 6000 W and 4000 W from 6 h to 10 h,respectively,the internal stresses of the films are measured by X...The diamond films adherent to Si substrate are deposited with the microwave plasma CVD(MPCVD) at microwave powers of 6000 W and 4000 W from 6 h to 10 h,respectively,the internal stresses of the films are measured by XRD.Spectral peak shift and widening are applied to calculate the magnitudes of macro and micro stresses.The results show that the macro stress is tensile.The internal stress can be controlled by the microwave power.With the microwave power increasing,the intrinsic and macro stresses decrease,and the micro stress increases significantly.Also,it can be found that the macro and micro stresses increase with deposited time when the other conditions are the same.展开更多
Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of t...Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of the Mgx Zn1–x O films occurred at x =0.44 and 0.51. Optical absorption spectra show that the absorption edges of the films shift to high-energy side with increasing Mg contents. In resonant Raman spectra, multiple-order Raman peaks originating from ZnO-like longitudinal optical phonons were observed. Moreover, the blue shift and the full width at half maximum of Raman scattering peaks increase continuously with x increasing from 0 to 0.28, which indicates that Zn is substituted by Mg in hexagonal lattice.展开更多
A Mythen detector has been equipped at the beamline 4B9 A of Beijing Synchrotron Radiation Facility(BSRF),which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction(XRD) full-profiles.I...A Mythen detector has been equipped at the beamline 4B9 A of Beijing Synchrotron Radiation Facility(BSRF),which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction(XRD) full-profiles.In this paper,the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector.The indium was heated from 303 to 433 K with a heating rate of 2 K/min.The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds.Rietveld refinement was used to extract the structural parameters.The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis.The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point(429.65 K).The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature,while the c-axis contracts with a cubic dependency on temperature.By the time-resolved XRD measurements,it was observed that the[200]preferred orientation can maintain to about 403.15 K.While(110) is the last and detectable crystal plane just before melting of the polycrystalline indium foil.This study is not only beneficial to the application of metal indium,but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.展开更多
BiFeO_3 (BFO) thin films with BaTiO_3 (BTO) or SrTiO_3 (STO) as buffer layer were epitaxially grown on SrRuO_3-covered SrTiO_3 substrates. X-ray diffraction measurements show that the BTO buffer causes tensile strain ...BiFeO_3 (BFO) thin films with BaTiO_3 (BTO) or SrTiO_3 (STO) as buffer layer were epitaxially grown on SrRuO_3-covered SrTiO_3 substrates. X-ray diffraction measurements show that the BTO buffer causes tensile strain in the BFO films, whereas the STO buffer causes compressive strain. Different ferroelectric domain structures caused by these two strain statuses are revealed by piezoelectric force microscopy. Electrical and magnetical measurements show that the tensile-strained BFO/BTO samples have reduced leakage current and large ferroelectric polarization and magnetization, compared with compressively strained BFO/STO. These results demonstrate that the electrical and magnetical properties of BFO thin films can be artificially modified by using a buffer layer.展开更多
To evaluate the influence of the ZnO buffer layer and Al proportion on the properties of ZnO: Al (AZO)/ZnO bi-layer films, a series of AZO/ZnO films are deposited on the quartz substrates by electron beam evaporation....To evaluate the influence of the ZnO buffer layer and Al proportion on the properties of ZnO: Al (AZO)/ZnO bi-layer films, a series of AZO/ZnO films are deposited on the quartz substrates by electron beam evaporation. The X-ray diffraction measurement shows that the crystal quality of the films is improved with the increase of the film thickness. The electrical properties of the films are investigated. The carrier concentration and Hall mobility both increase with the increase of buffer layer thickness. However, the resistivity reaches the lowest at about 50 nm-thick buffer layer. The lowest resistivity and the maximum Hall mobility are both obtained at 1 wt% Al concentration. But the optical transmittance of all the films is greater than 80% regardless of the buffer layer thickness with Al concentration lower than 5 wt% in the visible region.展开更多
Using XRD measurements of illite crystallinity,b0values of K-rich white micas and chemical compositions of chlorites combined with homogenization temperatures of fluid inclusions in calcite,the metamorphic P–T condit...Using XRD measurements of illite crystallinity,b0values of K-rich white micas and chemical compositions of chlorites combined with homogenization temperatures of fluid inclusions in calcite,the metamorphic P–T conditions of very low-grade metapelites from different depths in the 7 km Hongcan Well 1 in the Zoige?Depression,Sichuan,China,have been obtained in this paper.Knowledge of the tectonic evolution of the studied basin allows us to derive geothermal curves for Middle and Late Triassic time(the geothermal peak)and the present day(from thermal logging of the borehole).The retrograde P–T tracks from clockwise P–T–t loops have been revealed by the plotting of individual samples on each geotherm,which can be interpreted by the lithospheric thickening due to sedimentation and folding followed by continuous uplift and erosion.A stratigraphic log indicates that the Well penetrates the steep limb of a fold which perturbed the peak geotherm and caused some P–T paths to cross.展开更多
基金supported by EU project INCAS "Integration of Nanoreactor and multisite CAtalysis for a Sustainable chemical production" (Grant agreement no: 245988)
文摘The investigation by SEM/TEM, porosity, and X-ray diffraction measurements of the graphitization process starting from amorphous carbon nanospheres, prepared by glucose carbonization, is reported. Aspects studied are the annealing temperature in the 750–1000 °C range, the type of inert carrier gas, and time of treatment in the 2–6 h range. It is investigated how these parameters influence the structural and morphological characteristics of the carbon materials obtained as well as their nanostructure. It is shown that it is possible to maintain after graphitization the round-shaped macro morphology, a high surface area and porosity, and especially a large structural disorder in the graphitic layers stacking, with the presence of rather small ordered domains. These are characteristics interesting for various catalytic applications. The key in obtaining these characteristics is the thermal treatment in a flow of N2. It was demonstrated that the use of He rather than N2 does not allow obtaining the same results. The effect is attributed to the presence of traces of oxygen, enough to create the presence of oxygen functional groups on the surface temperatures higher than 750 °C, when graphitization occurs. These oxygen functional groups favor the graphitization process.
基金Project(50525619) supported by the National Natural Science Foundation of ChinaProject(306012) supported by the Key Foundation of Ministry of Education of China
文摘The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thermogravimetric analysis,X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2,which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere,i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.
基金supported by the National Natural Science Foundation of China(No.60576011)Key Laboratory Foundation of Tianjin(No.06TXTJJC14701)Colleges and Universities Foundation of Tianjin(No.20050519)
文摘The diamond films adherent to Si substrate are deposited with the microwave plasma CVD(MPCVD) at microwave powers of 6000 W and 4000 W from 6 h to 10 h,respectively,the internal stresses of the films are measured by XRD.Spectral peak shift and widening are applied to calculate the magnitudes of macro and micro stresses.The results show that the macro stress is tensile.The internal stress can be controlled by the microwave power.With the microwave power increasing,the intrinsic and macro stresses decrease,and the micro stress increases significantly.Also,it can be found that the macro and micro stresses increase with deposited time when the other conditions are the same.
基金supported by the National Natural Science Foundation of China (Grant No 50532050)
文摘Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of the Mgx Zn1–x O films occurred at x =0.44 and 0.51. Optical absorption spectra show that the absorption edges of the films shift to high-energy side with increasing Mg contents. In resonant Raman spectra, multiple-order Raman peaks originating from ZnO-like longitudinal optical phonons were observed. Moreover, the blue shift and the full width at half maximum of Raman scattering peaks increase continuously with x increasing from 0 to 0.28, which indicates that Zn is substituted by Mg in hexagonal lattice.
基金supported by the National Natural Science Foundationof China(Grant Nos.U1232203,U1432104,11405199,11305198 and U1332107)the special fund on repairing infrastructure and purchasing fixed assets of Ministry of Finance of China
文摘A Mythen detector has been equipped at the beamline 4B9 A of Beijing Synchrotron Radiation Facility(BSRF),which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction(XRD) full-profiles.In this paper,the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector.The indium was heated from 303 to 433 K with a heating rate of 2 K/min.The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds.Rietveld refinement was used to extract the structural parameters.The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis.The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point(429.65 K).The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature,while the c-axis contracts with a cubic dependency on temperature.By the time-resolved XRD measurements,it was observed that the[200]preferred orientation can maintain to about 403.15 K.While(110) is the last and detectable crystal plane just before melting of the polycrystalline indium foil.This study is not only beneficial to the application of metal indium,but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.
基金supported by the National Key Basic Research Program of China (Grant Nos. 2014CB921002, and 2013CBA01703)the National Natural Science Foundation of China (Grant Nos. 11174355, 11674385, and 11574365)the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07030200)
文摘BiFeO_3 (BFO) thin films with BaTiO_3 (BTO) or SrTiO_3 (STO) as buffer layer were epitaxially grown on SrRuO_3-covered SrTiO_3 substrates. X-ray diffraction measurements show that the BTO buffer causes tensile strain in the BFO films, whereas the STO buffer causes compressive strain. Different ferroelectric domain structures caused by these two strain statuses are revealed by piezoelectric force microscopy. Electrical and magnetical measurements show that the tensile-strained BFO/BTO samples have reduced leakage current and large ferroelectric polarization and magnetization, compared with compressively strained BFO/STO. These results demonstrate that the electrical and magnetical properties of BFO thin films can be artificially modified by using a buffer layer.
基金supported by the Foundation of Zhejiang Educational Committee (No.Z201018276)
文摘To evaluate the influence of the ZnO buffer layer and Al proportion on the properties of ZnO: Al (AZO)/ZnO bi-layer films, a series of AZO/ZnO films are deposited on the quartz substrates by electron beam evaporation. The X-ray diffraction measurement shows that the crystal quality of the films is improved with the increase of the film thickness. The electrical properties of the films are investigated. The carrier concentration and Hall mobility both increase with the increase of buffer layer thickness. However, the resistivity reaches the lowest at about 50 nm-thick buffer layer. The lowest resistivity and the maximum Hall mobility are both obtained at 1 wt% Al concentration. But the optical transmittance of all the films is greater than 80% regardless of the buffer layer thickness with Al concentration lower than 5 wt% in the visible region.
基金supported by the National Natural Science Foundation of China(41302047)the Special Fund for Basic Scientific Research of Central Colleges,Chang’an University(CHD2011JC185)
文摘Using XRD measurements of illite crystallinity,b0values of K-rich white micas and chemical compositions of chlorites combined with homogenization temperatures of fluid inclusions in calcite,the metamorphic P–T conditions of very low-grade metapelites from different depths in the 7 km Hongcan Well 1 in the Zoige?Depression,Sichuan,China,have been obtained in this paper.Knowledge of the tectonic evolution of the studied basin allows us to derive geothermal curves for Middle and Late Triassic time(the geothermal peak)and the present day(from thermal logging of the borehole).The retrograde P–T tracks from clockwise P–T–t loops have been revealed by the plotting of individual samples on each geotherm,which can be interpreted by the lithospheric thickening due to sedimentation and folding followed by continuous uplift and erosion.A stratigraphic log indicates that the Well penetrates the steep limb of a fold which perturbed the peak geotherm and caused some P–T paths to cross.
