A diamond film with a size of 6×6×0.5 mm^3 is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high pu...A diamond film with a size of 6×6×0.5 mm^3 is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high purity and large grain size, which is larger than 300 μm. Its resistivity is higher than 10^12 W· cm. Interlaced-finger electrodes are imprinted onto the diamond film to develop an x-ray detector. Ohmic contact is confirmed by checking the linearity of its current–voltage curve. The dark current is lower than 0.1 n A under an electric field of 30 k V cm^-1. The time response is 220 ps. The sensitivity is about 125 m A W^-1 under a biasing voltage of 100 V.A good linear radiation dose rate is also confirmed. This diamond detector is used to measure x-ray on a Z-pinch, which has a double-layer 'nested tungsten wire array'. The pronounced peaks in the measured waveform clearly characterize the x-ray bursts, which proves the performance of this diamond detector.展开更多
INTRODUCTIONThe studies on the quantitative distribution of the conventional elements and their phases in the sediments of the Changjiang Estuary are of great importance to the understanding of the chemical processes ...INTRODUCTIONThe studies on the quantitative distribution of the conventional elements and their phases in the sediments of the Changjiang Estuary are of great importance to the understanding of the chemical processes of ion exchange, absorption, desorption and flocculation in the estuary.展开更多
Two non-destructive analytical techniques (gamma spectrometer and X-ray diffractometer) were employed in the analysis of bauxite and rutile ore and their vicinity soil and control sourced within the Kanam and Wase min...Two non-destructive analytical techniques (gamma spectrometer and X-ray diffractometer) were employed in the analysis of bauxite and rutile ore and their vicinity soil and control sourced within the Kanam and Wase mineral exploration sites. The activity concentrations of natural radionuclides <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K in the soil samples received from bauxite and rutile mineral mining vicinities revealed high concentrations of <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K compared to the control soil samples sourced 500 m away from the mineral exploration vicinities. Radiological detriments RLI, AUI, Hin and Hex unveiled values exceeding the radiation standard concentration (>1) for soil. X-ray diffraction characterization of bauxite ore revealed the interlocking minerals of Bauxite (18)%, Albite (11)%, Garnet (15)%, Illite (6)% and Muscovite (43)% in various proportions obtained within the 2θ range (9.18 to 64.4) and a peak value (intensity, cps) of 3400. Pure bauxite percentage in the ore meets metallurgical grade (15 - 25)%. X-ray diffraction of rutile ore revealed the minerals of rutile (40)%, quartz (21.4)%, ilmenite (27)% and garnet (11.8)% found within the 2θ range (27.5 to 35.6) and a peak value intensity of 31.1 - 100.0 cps also meeting the metallurgical grade of 15% - 25%. The major environmental concern associated with the mineral-sands industry is the radiation hazards, pollution of ground-water sources from heavy metals, mineral transport with heavy equipment’s, dredging operations in fragile coastal area and clearing of vegetation.展开更多
Structural stability in terms of the decomposition temperature in LiMn_(2)O_(4) was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn_(2)O_(4) was found to have structural ...Structural stability in terms of the decomposition temperature in LiMn_(2)O_(4) was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn_(2)O_(4) was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn_(2)O_(4) varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn_(2)O_(4) materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.展开更多
The majority of extant reptiles are oviparous and produce eggs with three major components:embryo,yolk,and eggshell.The eggshell is species-specific and more diverse in squamate reptiles than in other amniote taxa.Her...The majority of extant reptiles are oviparous and produce eggs with three major components:embryo,yolk,and eggshell.The eggshell is species-specific and more diverse in squamate reptiles than in other amniote taxa.Here,we study the crystal structure,chemical composition,and bonding states of the eggshell of the green crested lizard Bronchocela cristatella.X-ray diffractometer(XRD)analysis showed the existence of two clearly defined and distinguishable crystalline phases,aragonite and calcite.Using the XRD data and a unit cell refinement routine,we identified two sets of cell parameters:a=4.956 A,b=7.965 A,and c=5.734 A for the aragonite phase;a=4.987 A,b=4.987 A,and c=17.056 A for the calcite structure.We used x-ray photoelectron spectroscopy to examine detailed elemental composition and bonding states and found that the eggshell was composed primarily of elements C,N,Ca,and O,with C,N and O bonded to various types of hybridization in the protein of the eggshell membrane.The Ca:C:O ratio for the calcium carbonate yielded a value of-7:8:21,which is close to the expected stoichiometric value of CaCO3.展开更多
Erbium dihydride thin films were prepared by pulsed laser deposition on Si(100) substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force micr...Erbium dihydride thin films were prepared by pulsed laser deposition on Si(100) substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force microscopy, X-ray diffractometer, transmission electron microscopy, and Fourier transform infrared spectroscopy and UV-vis spectroscopy. Surface morphology reveals the smooth surface of these films (RMS: from 0.503 to 2.849 nm). The presence of obviously-broadened peaks for diffraction planes (111) suggests a presence of very tiny crystallites distributed along a preferred crystallographic orientation. Transmission electron microscopy investigations confirmed the formation of tiny crystallites due to the implantation of erbium ions. Due to the increase of nominal H concentration, the intensity of the broad absorbance from 190-260 nm increased.展开更多
Raffia fibres are made from fibrous branches and leaves of Raffia palm. The membrane on the underside of each individual frond leaf is taken off to create a long thin fiber. They are usually waste materials which caus...Raffia fibres are made from fibrous branches and leaves of Raffia palm. The membrane on the underside of each individual frond leaf is taken off to create a long thin fiber. They are usually waste materials which cause a great environmental degradation. The characterization of Raffia palm fibers/ particles was investigated through X-ray diffractometer (XRD), thermogravimetric analysis (TGA/DTA), Fourier transform infrared spectrometry (FTIR), Scanning electron mi croscope with energy dispersive spectrometer (SEM/EDS) and Atomic force microscope (AFM). The various results obtained are equivalent to those of other agro-waste materials generally used in roofing sheets composites production. Hence, this work shows that Raffia palm fibers/particles can be a useful material for cement mortar composites production which can be used for production of roofing sheets.展开更多
Microcrystalline cellulose (MCC) was pretreated by using ionic liquids (ILs)-water mixtures solvent with solid acid catalysts. Different amount of water was considerate as the main variable. The peak shift of pretreat...Microcrystalline cellulose (MCC) was pretreated by using ionic liquids (ILs)-water mixtures solvent with solid acid catalysts. Different amount of water was considerate as the main variable. The peak shift of pretreated sample was determined by FT-IR related to the water content. The XRD was applied to characterize the change in MCC crystalline structure. Thermal decomposition technique was applied to investigate the thermal stability of pretreated MCC. The result indicated that three state of samples were occurred in pretreated MCC sample which was related the amount of water in ILs mixture system. XRD result suggested that the raw sample was distorted and transformed into a less ordered intermediate structure and the smaller crystallite size in lump state sample was obtained which could lead to lower thermal stability. This study revealed the physical chemicals properties, characteristic of molecular structures in MCC using ILs-water mixtures.展开更多
The ZnAl<sub>x</sub>Fe<sub>2-x</sub>O<sub>4</sub> (x = 0.0, 0.2 and 0.4) spinel ferrites were prepared by the conventional solid state reaction in air at 1350°C. The X-ray diff...The ZnAl<sub>x</sub>Fe<sub>2-x</sub>O<sub>4</sub> (x = 0.0, 0.2 and 0.4) spinel ferrites were prepared by the conventional solid state reaction in air at 1350°C. The X-ray diffraction of all the three samples showed sharp Bragg peaks indicating the formation of a single phase spinel structure. The lattice parameters of the samples were determined from the X-ray diffraction data using the Nelson-Riley extrapolation method. The lattice parameters, cation distribution and oxygen position parameters have also been determined by refining the data by the Rietveld method. Rietveld refinement of the XRD data reveals all the samples to possess cubic symmetry corresponding to the space group Fd3m. Lattice parameters were found to decrease with increasing Al concentration, i.e. 8.4322, 8.4002, and 8.3984 Åfor x = 0.0, 0.2 and 0.4, respectively.展开更多
Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))composition.The material was synthesized by conventional ceramic method(CS)and microwave sintering(MS).The presen...Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))composition.The material was synthesized by conventional ceramic method(CS)and microwave sintering(MS).The presence of single phase has been confirmed by X-ray diffraction and scanning electron microscopy of NBT ceramic.The later technique(MS)resulted in material with high density,dielectric properties and improved microstructure.The transition temperature was observed slightly higher for microwave sintered(MS)material.Longitudinal modulus measurements are very sensitive property to identify the phase transitions in ceramics.Longitudinal modulus(L)measurements were also employed on these samples in the frequency 136 kHz and can be studied in the wide temperature range 30℃to 400℃.The elastic behavior(L)showed a break at two temperatures(~200℃and 350℃)in both the conventional and microwave sintered ceramics.In NBT ceramics,permittivity anomalies are connected to modulus anomalies.The results are correlated with the dielectric measurements.This behavior explained in the light of structural phase transitions in the ferroelectric ceramics.展开更多
This note reports a new procedure of polycrystalline synthesis and a new technique of single crystal growth on AgGaS2, i.e. two-zone temperature oscillation vapor transporting and descending crucible with rotation. A ...This note reports a new procedure of polycrystalline synthesis and a new technique of single crystal growth on AgGaS2, i.e. two-zone temperature oscillation vapor transporting and descending crucible with rotation. A single phase dense AgGaS2 polycrystalline ingot was synthesized, and a crack-free AgGaS2 single crystal with 15 mm in diameter and 30 mm in length was grown by the techniques mentioned above. Structure integrity of the crystal was studied by the X-ray diffraction technique. Six order X-ray spectra from the {011} face of the crystal were obtained, and an anomalous phenomenon was observed for the first time that intensity of the higher order diffraction peak is much stronger than that of the lower order diffraction peak. Etch-pits of the crystal were observed by the scanning electron microscopy (SEM).展开更多
Sinee Coey et al. prepared the R<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> compounds by means of doping the nitrogenin gas-phase reaction, the magnetic properties of R<sub>2<...Sinee Coey et al. prepared the R<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> compounds by means of doping the nitrogenin gas-phase reaction, the magnetic properties of R<sub>2</sub>Fe<sub>17</sub> intermetallic compounds havebeen significantly improved. This aroused wide interest of relevant scientists. Recent re-search results show that Sm<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> has excellent intrinsic magnetic properties, but the nitridesR<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> consisting of other rare-earth elements except Sm, have an easy-plane anisotropy.In addition, Sm is very expensive. This kind of permanent magnetic materials is展开更多
基金supported by the National Key R&D Program of China(Grant No.2017YFE0301300)the Hunan Provincial Innovation Foundation for Postgraduate(Grant No.CX2018B588)。
文摘A diamond film with a size of 6×6×0.5 mm^3 is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high purity and large grain size, which is larger than 300 μm. Its resistivity is higher than 10^12 W· cm. Interlaced-finger electrodes are imprinted onto the diamond film to develop an x-ray detector. Ohmic contact is confirmed by checking the linearity of its current–voltage curve. The dark current is lower than 0.1 n A under an electric field of 30 k V cm^-1. The time response is 220 ps. The sensitivity is about 125 m A W^-1 under a biasing voltage of 100 V.A good linear radiation dose rate is also confirmed. This diamond detector is used to measure x-ray on a Z-pinch, which has a double-layer 'nested tungsten wire array'. The pronounced peaks in the measured waveform clearly characterize the x-ray bursts, which proves the performance of this diamond detector.
基金The project was supported by the National Natural Science Foundation of China.
文摘INTRODUCTIONThe studies on the quantitative distribution of the conventional elements and their phases in the sediments of the Changjiang Estuary are of great importance to the understanding of the chemical processes of ion exchange, absorption, desorption and flocculation in the estuary.
文摘Two non-destructive analytical techniques (gamma spectrometer and X-ray diffractometer) were employed in the analysis of bauxite and rutile ore and their vicinity soil and control sourced within the Kanam and Wase mineral exploration sites. The activity concentrations of natural radionuclides <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K in the soil samples received from bauxite and rutile mineral mining vicinities revealed high concentrations of <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K compared to the control soil samples sourced 500 m away from the mineral exploration vicinities. Radiological detriments RLI, AUI, Hin and Hex unveiled values exceeding the radiation standard concentration (>1) for soil. X-ray diffraction characterization of bauxite ore revealed the interlocking minerals of Bauxite (18)%, Albite (11)%, Garnet (15)%, Illite (6)% and Muscovite (43)% in various proportions obtained within the 2θ range (9.18 to 64.4) and a peak value (intensity, cps) of 3400. Pure bauxite percentage in the ore meets metallurgical grade (15 - 25)%. X-ray diffraction of rutile ore revealed the minerals of rutile (40)%, quartz (21.4)%, ilmenite (27)% and garnet (11.8)% found within the 2θ range (27.5 to 35.6) and a peak value intensity of 31.1 - 100.0 cps also meeting the metallurgical grade of 15% - 25%. The major environmental concern associated with the mineral-sands industry is the radiation hazards, pollution of ground-water sources from heavy metals, mineral transport with heavy equipment’s, dredging operations in fragile coastal area and clearing of vegetation.
基金by the National Natural Science Foundation of China(Grant No.12074273)the Doctoral Research Fund of Southwest University of Science and Technology(Grant No.20zx7136).
文摘Structural stability in terms of the decomposition temperature in LiMn_(2)O_(4) was systematically investigated by a series of high-temperature and high-pressure experiments.LiMn_(2)O_(4) was found to have structural stability up to 5 GPa at room temperature.Under ambient pressure,the compound decomposed at 1300℃.The decomposition temperature decreased with increasing pressure,yielding more complex decomposed products.Below the decomposition temperature,the crystal structure of LiMn_(2)O_(4) varied with pressure.The presented results in this study offer new insights into the thermal and pressure stability of LiMn_(2)O_(4) materials as a cathode for lithium-ion batteries that can operate under extreme conditions.Therefore,these findings may serve as a useful guide for future work for improving lithium-ion batteries.
文摘The majority of extant reptiles are oviparous and produce eggs with three major components:embryo,yolk,and eggshell.The eggshell is species-specific and more diverse in squamate reptiles than in other amniote taxa.Here,we study the crystal structure,chemical composition,and bonding states of the eggshell of the green crested lizard Bronchocela cristatella.X-ray diffractometer(XRD)analysis showed the existence of two clearly defined and distinguishable crystalline phases,aragonite and calcite.Using the XRD data and a unit cell refinement routine,we identified two sets of cell parameters:a=4.956 A,b=7.965 A,and c=5.734 A for the aragonite phase;a=4.987 A,b=4.987 A,and c=17.056 A for the calcite structure.We used x-ray photoelectron spectroscopy to examine detailed elemental composition and bonding states and found that the eggshell was composed primarily of elements C,N,Ca,and O,with C,N and O bonded to various types of hybridization in the protein of the eggshell membrane.The Ca:C:O ratio for the calcium carbonate yielded a value of-7:8:21,which is close to the expected stoichiometric value of CaCO3.
基金Funded by the Fund of the Science and Technology on Plasma Physics Laboratory(No.9140C680501110C6803)
文摘Erbium dihydride thin films were prepared by pulsed laser deposition on Si(100) substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force microscopy, X-ray diffractometer, transmission electron microscopy, and Fourier transform infrared spectroscopy and UV-vis spectroscopy. Surface morphology reveals the smooth surface of these films (RMS: from 0.503 to 2.849 nm). The presence of obviously-broadened peaks for diffraction planes (111) suggests a presence of very tiny crystallites distributed along a preferred crystallographic orientation. Transmission electron microscopy investigations confirmed the formation of tiny crystallites due to the implantation of erbium ions. Due to the increase of nominal H concentration, the intensity of the broad absorbance from 190-260 nm increased.
文摘Raffia fibres are made from fibrous branches and leaves of Raffia palm. The membrane on the underside of each individual frond leaf is taken off to create a long thin fiber. They are usually waste materials which cause a great environmental degradation. The characterization of Raffia palm fibers/ particles was investigated through X-ray diffractometer (XRD), thermogravimetric analysis (TGA/DTA), Fourier transform infrared spectrometry (FTIR), Scanning electron mi croscope with energy dispersive spectrometer (SEM/EDS) and Atomic force microscope (AFM). The various results obtained are equivalent to those of other agro-waste materials generally used in roofing sheets composites production. Hence, this work shows that Raffia palm fibers/particles can be a useful material for cement mortar composites production which can be used for production of roofing sheets.
文摘Microcrystalline cellulose (MCC) was pretreated by using ionic liquids (ILs)-water mixtures solvent with solid acid catalysts. Different amount of water was considerate as the main variable. The peak shift of pretreated sample was determined by FT-IR related to the water content. The XRD was applied to characterize the change in MCC crystalline structure. Thermal decomposition technique was applied to investigate the thermal stability of pretreated MCC. The result indicated that three state of samples were occurred in pretreated MCC sample which was related the amount of water in ILs mixture system. XRD result suggested that the raw sample was distorted and transformed into a less ordered intermediate structure and the smaller crystallite size in lump state sample was obtained which could lead to lower thermal stability. This study revealed the physical chemicals properties, characteristic of molecular structures in MCC using ILs-water mixtures.
文摘The ZnAl<sub>x</sub>Fe<sub>2-x</sub>O<sub>4</sub> (x = 0.0, 0.2 and 0.4) spinel ferrites were prepared by the conventional solid state reaction in air at 1350°C. The X-ray diffraction of all the three samples showed sharp Bragg peaks indicating the formation of a single phase spinel structure. The lattice parameters of the samples were determined from the X-ray diffraction data using the Nelson-Riley extrapolation method. The lattice parameters, cation distribution and oxygen position parameters have also been determined by refining the data by the Rietveld method. Rietveld refinement of the XRD data reveals all the samples to possess cubic symmetry corresponding to the space group Fd3m. Lattice parameters were found to decrease with increasing Al concentration, i.e. 8.4322, 8.4002, and 8.3984 Åfor x = 0.0, 0.2 and 0.4, respectively.
文摘Dielectric studies were carried out on a lead free Sodium Bismuth Titanate,NBT,(Na_(0.5)Bi_(0.5)TiO_(3))composition.The material was synthesized by conventional ceramic method(CS)and microwave sintering(MS).The presence of single phase has been confirmed by X-ray diffraction and scanning electron microscopy of NBT ceramic.The later technique(MS)resulted in material with high density,dielectric properties and improved microstructure.The transition temperature was observed slightly higher for microwave sintered(MS)material.Longitudinal modulus measurements are very sensitive property to identify the phase transitions in ceramics.Longitudinal modulus(L)measurements were also employed on these samples in the frequency 136 kHz and can be studied in the wide temperature range 30℃to 400℃.The elastic behavior(L)showed a break at two temperatures(~200℃and 350℃)in both the conventional and microwave sintered ceramics.In NBT ceramics,permittivity anomalies are connected to modulus anomalies.The results are correlated with the dielectric measurements.This behavior explained in the light of structural phase transitions in the ferroelectric ceramics.
基金This work was supported by the Sichuan Provincial Research Foundation of of China (Grant No: 99-479).
文摘This note reports a new procedure of polycrystalline synthesis and a new technique of single crystal growth on AgGaS2, i.e. two-zone temperature oscillation vapor transporting and descending crucible with rotation. A single phase dense AgGaS2 polycrystalline ingot was synthesized, and a crack-free AgGaS2 single crystal with 15 mm in diameter and 30 mm in length was grown by the techniques mentioned above. Structure integrity of the crystal was studied by the X-ray diffraction technique. Six order X-ray spectra from the {011} face of the crystal were obtained, and an anomalous phenomenon was observed for the first time that intensity of the higher order diffraction peak is much stronger than that of the lower order diffraction peak. Etch-pits of the crystal were observed by the scanning electron microscopy (SEM).
文摘Sinee Coey et al. prepared the R<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> compounds by means of doping the nitrogenin gas-phase reaction, the magnetic properties of R<sub>2</sub>Fe<sub>17</sub> intermetallic compounds havebeen significantly improved. This aroused wide interest of relevant scientists. Recent re-search results show that Sm<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> has excellent intrinsic magnetic properties, but the nitridesR<sub>2</sub>Fe<sub>17</sub>N<sub>x</sub> consisting of other rare-earth elements except Sm, have an easy-plane anisotropy.In addition, Sm is very expensive. This kind of permanent magnetic materials is