Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and ...Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.展开更多
The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,com...The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,comprehensively investigating of the dynamic crystal structure evolutions of Na_(x)TMO_(2)associating with Na ions extraction/intercalation and then deeply understanding of the relationships between electrochemical performances and phase structures drawing support from advanced characterization techniques are indispensable.In-situ high-energy X-ray diffraction(HEXRD),a powerful technology to distinguish the crystal structure of electrode materials,has been widely used to identify the phase evolutions of Na_(x)TMO_(2)and then profoundly revealed the electrochemical reaction processes.In this review,we begin with the descriptions of synchrotron characterization techniques and then present the advantages of synchrotron X-ray diffraction(XRD)over conventional XRD in detail.The optimizations of structural stability and electrochemical properties for P2-,O3-,and P2/O3-type Na_(x)TMO_(2)cathodes through single/dual-site substitution,high-entropy design,phase composition regulation,and surface engineering are summarized.The dynamic crystal structure evolutions of Na_(x)TMO_(2)polytypes during Na ion extraction/intercalation as well as corresponding structural enhancement mechanisms characterizing by means of HEXRD are concluded.The interior relationships between structure/component of Na_(x)TMO_(2)polytypes and their electrochemical properties are discussed.Finally,we look forward the research directions and issues in the route to improve the electrochemical properties of Na_(x)TMO_(2)cathodes for SIBs in the future and the combined utilizations of multiple characterization techniques.This review will provide significant guidelines for rational designs of high-performance Na_(x)TMO_(2)cathodes.展开更多
Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and ...Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and quantifying these superstructures hinder the optimization of pyrrhotite depression in flotation processes.To address this critical issue,synchrotron X-ray powder diffraction(S-XRPD)with Rietveld refinement was employed to quantify the distribution of superstructures in the feed and flotation concentrates of a copper–gold ore.To elucidate the mechanisms influencing depression,density functional theory(DFT)calculations were conducted to explore the electronic structures and surface reactivity of the pyrrhotite superstructures toward the adsorption of water,oxygen and hydroxyl ions(OH-)as dominant species present in the flotation process.S-XRPD analysis revealed that flotation recovery rates of pyrrhotite followed the order of 4C<6C<5C.DFT calculations indicated that the Fe 3d and S 3p orbital band centers exhibited a similar trend relative to the Fermi level with 4C being the closest.The Fe3d band center suggested that the 4C structure possessed a more reactive surface toward the oxygen reduction reaction,promoting the formation of hydrophilic Fe-OH sites.The S 3p band center order also implied that xanthate on the non-magnetic 5C and 6C surfaces could oxidize to dixanthogen,increasing hydrophobicity and floatability,while 4C formed less hydrophobic metal-xanthate complexes.Adsorption energy and charge transfer analyses of water,hydroxyl ions and molecular oxygen further supported the high reactivity and hydrophilic nature of 4C pyrrhotite.The strong bonding with hydroxyl ions indicated enhanced surface passivation by hydrophilic Fe–OOH complexes,aligning with the experimentally observed flotation order(4C<6C<5C).These findings provide a compelling correlation between experimental flotation results and electronic structure calculations,delivering crucial insights for optimizing flotation processes and improving pyrrhotite depression.This breakthrough opens up new opportunities to enhance the efficiency of flotation processes in the mining industry.展开更多
The X-ray powder diffraction data of the compound GdAlSi was studied by means of X-ray diffraction technique and refined by Rietveld method. The compound GdAlSi has tetragonal α-ThSi_2-type structure, space group I4_...The X-ray powder diffraction data of the compound GdAlSi was studied by means of X-ray diffraction technique and refined by Rietveld method. The compound GdAlSi has tetragonal α-ThSi_2-type structure, space group I4_1/amd (No.141), Z=4, the lattice parameters a=041234 (1) nm, c=1.44202(1) nm. The Smith and Snyder figure of merit [5] F_N is F_ 30=2521(36). The R-factors of Rietveld refinement are R_p=0.098 and R_ wp=0.128. The X-ray powder diffraction data are given. The field dependence of the magnetization measured at room temperature and the temperature variation of the inverse magnetic susceptibility of the compound GdAlSi were also presented.展开更多
The compound PrNiSn was studied by X ray powder diffraction technique. The crystal structure and the X ray diffraction data for this compound at room temperature were reported. The compound PrNiSn is orthorhombic wi...The compound PrNiSn was studied by X ray powder diffraction technique. The crystal structure and the X ray diffraction data for this compound at room temperature were reported. The compound PrNiSn is orthorhombic with lattice parameters a =0.74569(3) nm, b =0.76851(5) nm, c =0.45676(8) nm, V =0.26176 nm 3, Z =4 and D x=8.076 g·cm -3 , space group Pna2 1(33). The figure of merit F N for the compound is F 30 =54 (0.0093, 60).展开更多
A new compound K6FeNb15O42 was prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The X-ray powder diffraction data of the title compound was measured. K6FeNb15 O42 crystallizes in ...A new compound K6FeNb15O42 was prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The X-ray powder diffraction data of the title compound was measured. K6FeNb15 O42 crystallizes in the hexagonal system with unit cell parameters, a = 9. 1320(4) A ,c = 12. 0670(9) A , and space group P63/mcm (193) , z = 1. The calculated and measured densities are 4. 489 g/cm3 and 4. 485 g. cm3, respectively.展开更多
A new compound K6FeNb15O42 u(?) prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The XRD data of the title compound was determined. K6FeNb15O42 crystallizes the hexagonal system w...A new compound K6FeNb15O42 u(?) prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The XRD data of the title compound was determined. K6FeNb15O42 crystallizes the hexagonal system with unit cell parameters a=9. 1320(4) A,c=12. 0670(9) A, and space group P63/mcm(193) , 2=1. The calculated and measured densities are 4. 489 g/ cm3 and 4. 485 g. cm3, respectively.展开更多
オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3typ...オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3type structure, space group I4mm (No.107) a=0.42961(2) nm, c=098147(4) nm, V=0.018114 nm3, Z=2 and Dx=7.717 g·cm-3. The figure of merit FN for the powder data is F30=623 (0.0107, 45). Structure refinement was performed with 110 reflections and led to Rp=11.78% and Rwp=16.56%.展开更多
The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited o...The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited on WC-Co substrates in a home-made bias-enhanced HFCVD apparatus. Ethyl silicate (Si(OC2H5)4) is dissolved in acetone to obtain various Si/C mole ratio ranging from 0.1% to 1.4% in the reaction gas. Characterizations with SEM and XRD indicate increasing silicon concentration may result in grain size decreasing and diamond [110] texture becoming dominant. The residual stress values of as-deposited Si-doped diamond films are evaluated by both sin2ψ method, which measures the (220) diamond Bragg diffraction peaks using XRD, with ψ-values ranging from 0° to 45°, and Raman spectroscopy, which detects the diamond Raman peak shift from the natural diamond line at 1332 cm-1. The residual stress evolution on the silicon doping level estimated from the above two methods presents rather good agreements, exhibiting that all deposited Si-doped diamond films present compressive stress and the sample with Si/C mole ratio of 0.1% possesses the largest residual stress of ~1.75 GPa (Raman) or ~2.3 GPa (XRD). As the silicon doping level is up further, the residual stress reduces to a relative stable value around 1.3 GPa.展开更多
The compound GdNiSn has been studied by X-ray powder diffraction technique.The crystal structure and the X-ray diffraction data for this compound at room temperature are reported.The compound GdNiSn is orthorhombic wi...The compound GdNiSn has been studied by X-ray powder diffraction technique.The crystal structure and the X-ray diffraction data for this compound at room temperature are reported.The compound GdNiSn is orthorhombic with lattice parameters a=7.2044(1)A,b=7.6895(6)A,c=4.4772(4)A,space group Pna2_(1) and 4 formula units of GdNiSn in unit cell.The Smith and Snyder figure of index F_(30) for this compound is 35(0.015,59).展开更多
The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental t...The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients： αa = 5.8（3） × 10^-5, αb = 5.8 （1）× 10^-5, αc = 5.2（1）× 10^-5, and αv = 7.4（1） × 10^-3 ℃ 1 in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles α, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively.展开更多
A series of SnO2‐based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M （M=Mn, Zr, Ti and Pb） molar ratio of 9/1 were prepared by a co‐precipitation method and used for CH4 and CO oxidation. The Mn3＋, ...A series of SnO2‐based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M （M=Mn, Zr, Ti and Pb） molar ratio of 9/1 were prepared by a co‐precipitation method and used for CH4 and CO oxidation. The Mn3＋, Zr4＋, Ti4＋and Pb4＋cations are incorporated into the lattice of tetragonal rutile SnO2 to form a solid solution structure. As a consequence, the surface area and thermal stability of the catalysts are improved. Moreover, the oxygen species of the modified catalysts become easier to be reduced. Therefore, the oxidation activity over the catalysts was improved, except for the one modified by Pb oxide. Manganese oxide demonstrates the best promotional effects for SnO2. Using an X‐ray diffraction extrapolation method, the lattice capacity of SnO2 for Mn2O3 was 0.135 g Mn2O3/g SnO2, which indicates that to form stable solid solution, only 21%Sn4＋cations in the lattice can be maximally replaced by Mn3＋. If the amount of Mn3＋cations is over the capacity, Mn2O3 will be formed, which is not favorable for the activity of the catalysts. The Sn rich samples with only Sn‐Mn solid solution phase show higher activity than the ones with excess Mn2O3 species.展开更多
Additive manufacturing(AM)is a rapid prototyping technology based on the idea of discrete accumulation which off ers an advantage of economically fabricating a component with complex geometries in a rapid design-to-ma...Additive manufacturing(AM)is a rapid prototyping technology based on the idea of discrete accumulation which off ers an advantage of economically fabricating a component with complex geometries in a rapid design-to-manufacture cycle.However,various internal defects,such as balling,cracks,residual stress and porosity,are inevitably occurred during AM due to the complexity of laser/electron beam-powder interaction,rapid melting and solidification process,and microstructure evolution.The existence of porosity defects can potentially deteriorate the mechanical properties of selective laser melting(SLM)components,such as material stiff ness,hardness,tensile strength,and fatigue resistance performance.Synchrotron X-ray imaging and diffraction are important non-destructive means to elaborately characterize the internal defect characteristics and mechanical properties of AM parts.This paper presents a review on the application of synchrotron X-ray in identifying and verifying the quality and requirement of AM parts.Defects,microstructures and mechanical properties of printed components characterized by synchrotron X-ray imaging and diffraction are summarized in this review.Subsequently,this paper also elaborates on the online characterization of the evolution of the microstructure during AM using synchrotron X-ray imaging,and introduces the method for measuring AM stress by X-ray diffraction(XRD).Finally,the future application of synchrotron X-ray characterization in the AM is prospected.展开更多
Characterizing the microstructure and deformation mechanism associated with the performances and properties of metallic materials is of great importance in understanding the microstructure-property relationship.The pa...Characterizing the microstructure and deformation mechanism associated with the performances and properties of metallic materials is of great importance in understanding the microstructure-property relationship.The past few decades have witnessed the rapid development of characterization techniques from optical microscopy to electron microscopy,although these conventional methods are generally limited to the sample surface because of the intrinsic opaque nature of metallic materials.Advanced synchrotron radiation(SR)facilities can produce X-rays with strong penetrability and high spatiotemporal resolution,and thereby enabling the non-destructive visualization of full-field structural information in three dimensions.Tremendous endeavors were devoted to the 3 rd generation SR over the past three decades,in which X-ray beams have been focused down to 100 nm.In this paper,recent progresses on SR-related characterization technologies were reviewed,with particular emphases on the fundamentals of synchrotron X-ray imaging and synchrotron X-ray diffraction,as well as their applications in the in situ observations of material preparation(e.g.,in situ dendrite growth during solidification)and service under extreme environment(e.g.,in situ mechanics).Future innovations toward next-generation SR and newly emerging SRbased technologies such as dark-field X-ray microscopy and Bragg coherent X-ray diffraction imaging were also advocated.展开更多
X-ray diffractometry was utilized to study the mineralogical characteristics of the inhalable particles （PM10） sampled during two dust storms in Beijing city on March 18th and May 21st, 2008. We confirm, for the fir...X-ray diffractometry was utilized to study the mineralogical characteristics of the inhalable particles （PM10） sampled during two dust storms in Beijing city on March 18th and May 21st, 2008. We confirm, for the first time, that there stably exists ammonium chloride in the atmosphere when temperature is low. The total sulfates particles were affected by relative humidity. Both species and concentration of sulfates decreased first and then grew back by the end of each dust storm. Koninckite, a phosphate mineral never reported as particulate aerosol before, was identified. Meanwhile, our result shows that a chemical modification on dust minerals occurs during long range transportation. PM10 samples collected during the period of dust storms were dominated by crustal minerals such as quartz, illite/smectite, illite, chlorite, feldspar and calcite, and were notably higher in concentration than that in normal periods of time. The amounts of total sulfates, calcite and feldspar altered in each dust storm. It is derived from 24-hour isentropic backward trajectories that two dust events in spring 2008 originated in different sources.展开更多
The phase transformations during thermomechanical processing can be employed to optimize mechanical properties of β-type Ti alloys.However,such understandings are still lacking for the alloy consisting of dual β+α&...The phase transformations during thermomechanical processing can be employed to optimize mechanical properties of β-type Ti alloys.However,such understandings are still lacking for the alloy consisting of dual β+α" phases in solution-treated and quenched state.In this paper,the phase transformations in a Ti38 Nb model alloy subjected to different thermomechanical processing were investigated by using synchrotron X-ray diffraction(SXRD) experiments,and their influence on the Young’s modulus was discussed.The results indicated that highdensity dislocations introduced by cold rolling still existed after annealing at temperatures lower than 573 K,which can decrease the martensitic transformation start temperature to below room temperature.With annealing temperatures increasing,the α"→β,β→ω_(iso),and β→α phase transformations occurred successively.At annealing temperature of 473 K,the specimen consisted of a trace of α"and ω phases as well as dominant β phase which was kept to room temperature by the high density of dislocations,rather than by the chemical stabilization.As a result,an ultralow Young’s modulus of 25.9 GPa was realized.Our investigation not only provides in-depth understandings of the phase transformations during thermomechanical processing of β-type Ti alloys,but also sheds light on designing biomedical Ti alloys with ultralow Young’s modulus.展开更多
A new method for quantitative phase analysis is proposed by using X-ray diffraction multi-peak match intensity ratio. This method can obtain the multi-peak match intensity ratio among each phase in the mixture sample ...A new method for quantitative phase analysis is proposed by using X-ray diffraction multi-peak match intensity ratio. This method can obtain the multi-peak match intensity ratio among each phase in the mixture sample by using all diffraction peak data in the mixture sample X-ray diffraction spectrum and combining the relative intensity distribution data of each phase standard peak in JCPDS card to carry on the least square method regression analysis. It is benefit to improve the precision of quantitative phase analysis that the given single line ratio which is usually adopted is taken the place of the multi-peak match intensity ratio and is used in X-ray diffraction quantitative phase analysis of the mixture sample. By analyzing four-group mixture sample, adopting multi-peak match intensity ratio and X-ray diffraction quantitative phase analysis principle of combining the adiabatic and matrix flushing method, it is tested that the experimental results are identical with theory.展开更多
The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchro...The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchrotron X-ray diffraction is able to go through the interior of sample and can be carried out with in situ environment,and thus,it can obtain more statistics information in real time comparing with traditional methods,such as electron and optical microscopies.In this study,in situ heating synchrotron X-ray diffraction was carried out to study the phase evolution in a typicalγ′phase precipitation strengthened Ni-based superalloy,Waspaloy,from 29 to 1050°C.Theγ′,γ,M_(23)C_(6)and M C phases,including their lattice parameters,misfits,dissolution behavior and thermal expansion coefficients,were mainly investigated.Theγ′phase and M_(23)C_(6)carbides appeared obvious dissolution during heating and re-precipitated when the temperature dropped to room temperature.Combining with the microscopy results,we can indicate that the dissolution of M_(23)C_(6)leads to the growth of grain andγ′phase cannot be completely dissolved for the short holding time above the solution temperature.Besides,the coefficients of thermal expansions of all the phases are calculated and fitted as polynomials.展开更多
文摘Magnesium(Mg)alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed(hcp)crystal structures,often leading to tension-compression asymmetries.Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications,particularly in the lightweight transportation industries.Nevertheless,the underlying deformation mechanisms(e.g.,slip versus twinning)at each deformation stage during tension and compression have not been fully understood.In this study,we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy,i.e.,an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca,during the synchrotron X-ray diffraction.Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples:(i)The tensile deformation is dominated by dislocation slips,with activation of non-basaland<c+a>slip,but deformation twinning is suppressed.(ii)The compressive deformation shows early-stage tensile twinning,followed by dislocation slips.Twinning induces grain reorientation,leading to significant lattice strain evolution aligned with the texture.The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression,which facilitates the activation of tensile twins.During tension,the strain hardening rate(SHR)drops significantly after yielding due to limited activated slip systems.In contrast,the samples under compression exhibit significant increases in SHR after yielding.During compression,dislocation multiplication dominates the initial strain hardening,while twinning progressively contributes more significantly than dislocation slip at higher strains.This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.
基金supported by the State Grid Corporation Science and Technology Project(No.5419-202158503A-0-5-ZN)。
文摘The detrimental phase transformations of sodium layered transition metal oxides(Na_(x)TMO_(2))during desodiation/sodiation seriously suppress their practical applications for sodium ion batteries(SIBs).Undoubtedly,comprehensively investigating of the dynamic crystal structure evolutions of Na_(x)TMO_(2)associating with Na ions extraction/intercalation and then deeply understanding of the relationships between electrochemical performances and phase structures drawing support from advanced characterization techniques are indispensable.In-situ high-energy X-ray diffraction(HEXRD),a powerful technology to distinguish the crystal structure of electrode materials,has been widely used to identify the phase evolutions of Na_(x)TMO_(2)and then profoundly revealed the electrochemical reaction processes.In this review,we begin with the descriptions of synchrotron characterization techniques and then present the advantages of synchrotron X-ray diffraction(XRD)over conventional XRD in detail.The optimizations of structural stability and electrochemical properties for P2-,O3-,and P2/O3-type Na_(x)TMO_(2)cathodes through single/dual-site substitution,high-entropy design,phase composition regulation,and surface engineering are summarized.The dynamic crystal structure evolutions of Na_(x)TMO_(2)polytypes during Na ion extraction/intercalation as well as corresponding structural enhancement mechanisms characterizing by means of HEXRD are concluded.The interior relationships between structure/component of Na_(x)TMO_(2)polytypes and their electrochemical properties are discussed.Finally,we look forward the research directions and issues in the route to improve the electrochemical properties of Na_(x)TMO_(2)cathodes for SIBs in the future and the combined utilizations of multiple characterization techniques.This review will provide significant guidelines for rational designs of high-performance Na_(x)TMO_(2)cathodes.
基金supported by the Australian Research Council Linkage Project(No.LP200200717)co sponsored by Newmont Corporation(United States)and Vega Industries(India)+1 种基金the Powder Diffraction Beamline at the Australia’s Nuclear Science and Technology Organisation(No.PDR19870),Australiathe Centre for Microscopy and Microanalysis at the University of Queensland(No.1366),Australia。
文摘Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and quantifying these superstructures hinder the optimization of pyrrhotite depression in flotation processes.To address this critical issue,synchrotron X-ray powder diffraction(S-XRPD)with Rietveld refinement was employed to quantify the distribution of superstructures in the feed and flotation concentrates of a copper–gold ore.To elucidate the mechanisms influencing depression,density functional theory(DFT)calculations were conducted to explore the electronic structures and surface reactivity of the pyrrhotite superstructures toward the adsorption of water,oxygen and hydroxyl ions(OH-)as dominant species present in the flotation process.S-XRPD analysis revealed that flotation recovery rates of pyrrhotite followed the order of 4C<6C<5C.DFT calculations indicated that the Fe 3d and S 3p orbital band centers exhibited a similar trend relative to the Fermi level with 4C being the closest.The Fe3d band center suggested that the 4C structure possessed a more reactive surface toward the oxygen reduction reaction,promoting the formation of hydrophilic Fe-OH sites.The S 3p band center order also implied that xanthate on the non-magnetic 5C and 6C surfaces could oxidize to dixanthogen,increasing hydrophobicity and floatability,while 4C formed less hydrophobic metal-xanthate complexes.Adsorption energy and charge transfer analyses of water,hydroxyl ions and molecular oxygen further supported the high reactivity and hydrophilic nature of 4C pyrrhotite.The strong bonding with hydroxyl ions indicated enhanced surface passivation by hydrophilic Fe–OOH complexes,aligning with the experimentally observed flotation order(4C<6C<5C).These findings provide a compelling correlation between experimental flotation results and electronic structure calculations,delivering crucial insights for optimizing flotation processes and improving pyrrhotite depression.This breakthrough opens up new opportunities to enhance the efficiency of flotation processes in the mining industry.
文摘The X-ray powder diffraction data of the compound GdAlSi was studied by means of X-ray diffraction technique and refined by Rietveld method. The compound GdAlSi has tetragonal α-ThSi_2-type structure, space group I4_1/amd (No.141), Z=4, the lattice parameters a=041234 (1) nm, c=1.44202(1) nm. The Smith and Snyder figure of merit [5] F_N is F_ 30=2521(36). The R-factors of Rietveld refinement are R_p=0.098 and R_ wp=0.128. The X-ray powder diffraction data are given. The field dependence of the magnetization measured at room temperature and the temperature variation of the inverse magnetic susceptibility of the compound GdAlSi were also presented.
文摘The compound PrNiSn was studied by X ray powder diffraction technique. The crystal structure and the X ray diffraction data for this compound at room temperature were reported. The compound PrNiSn is orthorhombic with lattice parameters a =0.74569(3) nm, b =0.76851(5) nm, c =0.45676(8) nm, V =0.26176 nm 3, Z =4 and D x=8.076 g·cm -3 , space group Pna2 1(33). The figure of merit F N for the compound is F 30 =54 (0.0093, 60).
基金Fund by International Centre for Dlffractlon Data.
文摘A new compound K6FeNb15O42 was prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The X-ray powder diffraction data of the title compound was measured. K6FeNb15 O42 crystallizes in the hexagonal system with unit cell parameters, a = 9. 1320(4) A ,c = 12. 0670(9) A , and space group P63/mcm (193) , z = 1. The calculated and measured densities are 4. 489 g/cm3 and 4. 485 g. cm3, respectively.
文摘A new compound K6FeNb15O42 u(?) prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The XRD data of the title compound was determined. K6FeNb15O42 crystallizes the hexagonal system with unit cell parameters a=9. 1320(4) A,c=12. 0670(9) A, and space group P63/mcm(193) , 2=1. The calculated and measured densities are 4. 489 g/ cm3 and 4. 485 g. cm3, respectively.
文摘オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3type structure, space group I4mm (No.107) a=0.42961(2) nm, c=098147(4) nm, V=0.018114 nm3, Z=2 and Dx=7.717 g·cm-3. The figure of merit FN for the powder data is F30=623 (0.0107, 45). Structure refinement was performed with 110 reflections and led to Rp=11.78% and Rwp=16.56%.
基金Project (51005154) supported by the National Natural Science Foundation of ChinaProject (12CG11) supported by the Chenguang Program of Shanghai Municipal Education Commission, ChinaProject (201104271) supported by the China Postdoctoral Science Foundation
文摘The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited on WC-Co substrates in a home-made bias-enhanced HFCVD apparatus. Ethyl silicate (Si(OC2H5)4) is dissolved in acetone to obtain various Si/C mole ratio ranging from 0.1% to 1.4% in the reaction gas. Characterizations with SEM and XRD indicate increasing silicon concentration may result in grain size decreasing and diamond [110] texture becoming dominant. The residual stress values of as-deposited Si-doped diamond films are evaluated by both sin2ψ method, which measures the (220) diamond Bragg diffraction peaks using XRD, with ψ-values ranging from 0° to 45°, and Raman spectroscopy, which detects the diamond Raman peak shift from the natural diamond line at 1332 cm-1. The residual stress evolution on the silicon doping level estimated from the above two methods presents rather good agreements, exhibiting that all deposited Si-doped diamond films present compressive stress and the sample with Si/C mole ratio of 0.1% possesses the largest residual stress of ~1.75 GPa (Raman) or ~2.3 GPa (XRD). As the silicon doping level is up further, the residual stress reduces to a relative stable value around 1.3 GPa.
基金Supported by a Grant-in-Aid from the International Centre for Diffraction Data and the Natural Science Foundation of Guangxi Zhuang Autonomous Region。
文摘The compound GdNiSn has been studied by X-ray powder diffraction technique.The crystal structure and the X-ray diffraction data for this compound at room temperature are reported.The compound GdNiSn is orthorhombic with lattice parameters a=7.2044(1)A,b=7.6895(6)A,c=4.4772(4)A,space group Pna2_(1) and 4 formula units of GdNiSn in unit cell.The Smith and Snyder figure of index F_(30) for this compound is 35(0.015,59).
基金financially supported by the Natural Science Foundation of China(Grant 40872033)the Fundamental Research Funds for the Central Universities(to XL)the Natural Sciences and Engineering Research Council of Canada(to MF)
文摘The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients： αa = 5.8（3） × 10^-5, αb = 5.8 （1）× 10^-5, αc = 5.2（1）× 10^-5, and αv = 7.4（1） × 10^-3 ℃ 1 in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles α, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively.
基金supported by the National Natural Science Foundation of China (21263015,21567016 and 21503106)the Education Department Foundation of Jiangxi Province (KJLD14005 and GJJ150016)the Natural Science Foundation of Jiangxi Province (20142BAB213013 and 20151BBE50006),which are greatly acknowledged by the authors~~
文摘A series of SnO2‐based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M （M=Mn, Zr, Ti and Pb） molar ratio of 9/1 were prepared by a co‐precipitation method and used for CH4 and CO oxidation. The Mn3＋, Zr4＋, Ti4＋and Pb4＋cations are incorporated into the lattice of tetragonal rutile SnO2 to form a solid solution structure. As a consequence, the surface area and thermal stability of the catalysts are improved. Moreover, the oxygen species of the modified catalysts become easier to be reduced. Therefore, the oxidation activity over the catalysts was improved, except for the one modified by Pb oxide. Manganese oxide demonstrates the best promotional effects for SnO2. Using an X‐ray diffraction extrapolation method, the lattice capacity of SnO2 for Mn2O3 was 0.135 g Mn2O3/g SnO2, which indicates that to form stable solid solution, only 21%Sn4＋cations in the lattice can be maximally replaced by Mn3＋. If the amount of Mn3＋cations is over the capacity, Mn2O3 will be formed, which is not favorable for the activity of the catalysts. The Sn rich samples with only Sn‐Mn solid solution phase show higher activity than the ones with excess Mn2O3 species.
基金financially supported by the National Nature Science Foundation of China(No.51701112)the National Key Research and Development Program of China(No.2019YFA0705300)+2 种基金the Shanghai Rising-Star Program(Nos.20QA1403800 and 21QC1401500)the Shanghai Science and Technology Committee(No.19DZ1100704)the open fund of State Key Laboratory of Solidifi cation Processing in NWPU(Grant No.SKLSP202107)。
文摘Additive manufacturing(AM)is a rapid prototyping technology based on the idea of discrete accumulation which off ers an advantage of economically fabricating a component with complex geometries in a rapid design-to-manufacture cycle.However,various internal defects,such as balling,cracks,residual stress and porosity,are inevitably occurred during AM due to the complexity of laser/electron beam-powder interaction,rapid melting and solidification process,and microstructure evolution.The existence of porosity defects can potentially deteriorate the mechanical properties of selective laser melting(SLM)components,such as material stiff ness,hardness,tensile strength,and fatigue resistance performance.Synchrotron X-ray imaging and diffraction are important non-destructive means to elaborately characterize the internal defect characteristics and mechanical properties of AM parts.This paper presents a review on the application of synchrotron X-ray in identifying and verifying the quality and requirement of AM parts.Defects,microstructures and mechanical properties of printed components characterized by synchrotron X-ray imaging and diffraction are summarized in this review.Subsequently,this paper also elaborates on the online characterization of the evolution of the microstructure during AM using synchrotron X-ray imaging,and introduces the method for measuring AM stress by X-ray diffraction(XRD).Finally,the future application of synchrotron X-ray characterization in the AM is prospected.
基金financially supported by the National Key Research and Development Plan(Grant Nos.2020YFA0405900,2017YFA0403803)the National Natural Science Foundation of China(Grant No.51927801)the Natural Science Foundation of Jiangsu Province(Grant No.BK20202010)。
文摘Characterizing the microstructure and deformation mechanism associated with the performances and properties of metallic materials is of great importance in understanding the microstructure-property relationship.The past few decades have witnessed the rapid development of characterization techniques from optical microscopy to electron microscopy,although these conventional methods are generally limited to the sample surface because of the intrinsic opaque nature of metallic materials.Advanced synchrotron radiation(SR)facilities can produce X-rays with strong penetrability and high spatiotemporal resolution,and thereby enabling the non-destructive visualization of full-field structural information in three dimensions.Tremendous endeavors were devoted to the 3 rd generation SR over the past three decades,in which X-ray beams have been focused down to 100 nm.In this paper,recent progresses on SR-related characterization technologies were reviewed,with particular emphases on the fundamentals of synchrotron X-ray imaging and synchrotron X-ray diffraction,as well as their applications in the in situ observations of material preparation(e.g.,in situ dendrite growth during solidification)and service under extreme environment(e.g.,in situ mechanics).Future innovations toward next-generation SR and newly emerging SRbased technologies such as dark-field X-ray microscopy and Bragg coherent X-ray diffraction imaging were also advocated.
基金supported by the National Natural Science Foundation of China(No.40972033, 40872034,40572032)the 15th and 16th Laboratory Funds of Peking University
文摘X-ray diffractometry was utilized to study the mineralogical characteristics of the inhalable particles （PM10） sampled during two dust storms in Beijing city on March 18th and May 21st, 2008. We confirm, for the first time, that there stably exists ammonium chloride in the atmosphere when temperature is low. The total sulfates particles were affected by relative humidity. Both species and concentration of sulfates decreased first and then grew back by the end of each dust storm. Koninckite, a phosphate mineral never reported as particulate aerosol before, was identified. Meanwhile, our result shows that a chemical modification on dust minerals occurs during long range transportation. PM10 samples collected during the period of dust storms were dominated by crustal minerals such as quartz, illite/smectite, illite, chlorite, feldspar and calcite, and were notably higher in concentration than that in normal periods of time. The amounts of total sulfates, calcite and feldspar altered in each dust storm. It is derived from 24-hour isentropic backward trajectories that two dust events in spring 2008 originated in different sources.
基金financially supported by the Fundamental Research Funds for the Central Universities (No.2017QNA04)。
文摘The phase transformations during thermomechanical processing can be employed to optimize mechanical properties of β-type Ti alloys.However,such understandings are still lacking for the alloy consisting of dual β+α" phases in solution-treated and quenched state.In this paper,the phase transformations in a Ti38 Nb model alloy subjected to different thermomechanical processing were investigated by using synchrotron X-ray diffraction(SXRD) experiments,and their influence on the Young’s modulus was discussed.The results indicated that highdensity dislocations introduced by cold rolling still existed after annealing at temperatures lower than 573 K,which can decrease the martensitic transformation start temperature to below room temperature.With annealing temperatures increasing,the α"→β,β→ω_(iso),and β→α phase transformations occurred successively.At annealing temperature of 473 K,the specimen consisted of a trace of α"and ω phases as well as dominant β phase which was kept to room temperature by the high density of dislocations,rather than by the chemical stabilization.As a result,an ultralow Young’s modulus of 25.9 GPa was realized.Our investigation not only provides in-depth understandings of the phase transformations during thermomechanical processing of β-type Ti alloys,but also sheds light on designing biomedical Ti alloys with ultralow Young’s modulus.
文摘A new method for quantitative phase analysis is proposed by using X-ray diffraction multi-peak match intensity ratio. This method can obtain the multi-peak match intensity ratio among each phase in the mixture sample by using all diffraction peak data in the mixture sample X-ray diffraction spectrum and combining the relative intensity distribution data of each phase standard peak in JCPDS card to carry on the least square method regression analysis. It is benefit to improve the precision of quantitative phase analysis that the given single line ratio which is usually adopted is taken the place of the multi-peak match intensity ratio and is used in X-ray diffraction quantitative phase analysis of the mixture sample. By analyzing four-group mixture sample, adopting multi-peak match intensity ratio and X-ray diffraction quantitative phase analysis principle of combining the adiabatic and matrix flushing method, it is tested that the experimental results are identical with theory.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.11805009 and 51921001)the Fundamental Research Funds for the Central Universities(Grant No.06111020)。
文摘The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchrotron X-ray diffraction is able to go through the interior of sample and can be carried out with in situ environment,and thus,it can obtain more statistics information in real time comparing with traditional methods,such as electron and optical microscopies.In this study,in situ heating synchrotron X-ray diffraction was carried out to study the phase evolution in a typicalγ′phase precipitation strengthened Ni-based superalloy,Waspaloy,from 29 to 1050°C.Theγ′,γ,M_(23)C_(6)and M C phases,including their lattice parameters,misfits,dissolution behavior and thermal expansion coefficients,were mainly investigated.Theγ′phase and M_(23)C_(6)carbides appeared obvious dissolution during heating and re-precipitated when the temperature dropped to room temperature.Combining with the microscopy results,we can indicate that the dissolution of M_(23)C_(6)leads to the growth of grain andγ′phase cannot be completely dissolved for the short holding time above the solution temperature.Besides,the coefficients of thermal expansions of all the phases are calculated and fitted as polynomials.
