To overcome the limitation in formability at room temperature,manufacturers have developed magnesium alloys with remarkable properties by adding rare-earth elements.The rare-earth magnesium alloys behave differently f...To overcome the limitation in formability at room temperature,manufacturers have developed magnesium alloys with remarkable properties by adding rare-earth elements.The rare-earth magnesium alloys behave differently from the conventional alloys,especially with respect to their coupled anisotropic and strain rate sensitive behavior.In the current work,such behavior of the rare-earth Mg alloy ZEK100 sheet at room temperature is investigated with the aid of the elastic viscoplastic self-consistent polycrystal plasticity model.Different strain rate sensitivities(SRSs)for various deformation modes are employed by the model to simulate the strain rate sensitive behaviors under different loading directions and loading rates.Good agreement between the experiments and simulations reveals the importance and necessity of using different SRSs for each deformation mode in hexagonal close-packed metals.Furthermore,the relative activities of each deformation mode and the texture evolution during different loadings are discussed.The anisotropic and strain rate sensitive behavior is ascribed to the various operating deformation modes with different SRSs during loading along different directions.展开更多
During the past decades,with the increasing demands in lightweight structural materials,Mg alloys with low density and high performance have been extensively investigated and partly applied in some industries.Especial...During the past decades,with the increasing demands in lightweight structural materials,Mg alloys with low density and high performance have been extensively investigated and partly applied in some industries.Especially when rare earth(RE)elements are added as major alloying elements to Mg alloys,the alloy strength and creep resistance are greatly improved,which have promoted several series of Mg-RE alloys.This paper reviews the progress and developments of high-performance Mg-RE alloys in recent years with emphasis on cast alloys.The main contents include the alloy design,melt purification,grain refinement,castability,novel liquid casting and semisolid forming approaches,and the industrial applications or trials made of Mg-RE alloys.The review will provide insights for future developments of new alloys,techniques and applications of Mg alloys.展开更多
Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the err...Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the error compensation model of fuzzy system,is proposed to solve the prob- lem that the component content in countercurrent rare-earth extraction process is hardly measured on-line.An industry experiment in the extraction Y process by HAB using this hybrid soft-sensor proves its effectiveness.展开更多
The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we exa...The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.展开更多
The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can b...The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.展开更多
This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma...This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rareearth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments' provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr(651–1352 ppm), Ba(56–157 ppm), V(38–90 ppm),and Sr(15.1–59.6 ppm). Average values of Co and Ni were1.5 and 0.7 ppm, respectively. Trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies,typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment.^(18 )O values ranged from+ 15.4 to + 21.2% for the investigated samples, consistent with a residual material derived from chemicalweathering of felsic rock and redeposited in a sedimentary basin(typical values of + 19 to + 21.2%). While in the basin, the sediments experienced extended interactions with meteoric water enriched in d D and d16 O. However,the variation in d D and d16 O values for the investigated samples is attributed to the high temperature of formation(54–91 °C). The d D and d^(18 )O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot,tropical climatic conditions.展开更多
The corrosion resistance of three Mg alloys containing rare-earth elements(WE43,EV31 and ZE41)was studied and compared to that of two Mg-Al alloys(AZ31 and AZ91)and of pure Mg(99.95 wt.%).Current-voltage curves and el...The corrosion resistance of three Mg alloys containing rare-earth elements(WE43,EV31 and ZE41)was studied and compared to that of two Mg-Al alloys(AZ31 and AZ91)and of pure Mg(99.95 wt.%).Current-voltage curves and electrochemical impedance measurements were performed with rotating disk electrodes in an aerated 0.1 M Na_(2)SO_(4)solution.For all the alloys,it was confirmed that the intermetallic particles acted as local cathodes and that more protective films were formed on the alloys surface by comparison with the pure Mg.Corrosion rates were determined from inductive coupled plasma-optical emission spectroscopy measurements and from the electrochemical measurements.Higher corrosion rates were observed for the rare-earth Mg alloys compared to the AZ series alloys.These data allowed the corrosion mechanisms to be discussed.展开更多
The rare-earth optical fiber is made of organic material and inorganic rare earth material.It can be used to absorb and transfer solar energy.When sunlight irradiates, it may absorb and transfer solar energy automatic...The rare-earth optical fiber is made of organic material and inorganic rare earth material.It can be used to absorb and transfer solar energy.When sunlight irradiates, it may absorb and transfer solar energy automatically; while at night or without sunlight it may give out light and play role of decoration.By utilizing high transmissivity of organic material and heat-resisting performance of inorganic material, we know the reorganization of material performance under the melting condition, and make empty core bear the high temperature of 150 ～200 ℃.When the light spreads in light guide, some light energy travels along the direction of light guide, and is introduced in the room directly.Another part of light energy is absorbed and stored by light guide, and can release light again after 8 ～ 12 h.展开更多
Due to their low symmetry in crystal structure,low elastic modulus(~45 GPa)and low yielding stress,magnesium(Mg)alloys exhibit strong inelastic behaviors during unloading.As more and more Mg alloys are developed,their...Due to their low symmetry in crystal structure,low elastic modulus(~45 GPa)and low yielding stress,magnesium(Mg)alloys exhibit strong inelastic behaviors during unloading.As more and more Mg alloys are developed,their unloading behaviors were less investigated,especially for rare-earth(RE)Mg alloys.In the current work,the unloading behaviors of the RE Mg alloy ZE10 sheet is carefully studied by both mechanical tests and crystal plasticity modeling.In terms of the stress-strain curves,the inelastic strain,the chord modulus,and the active deformation mechanisms,the substantial anisotropy and the loading path dependency of the unloading behaviors of ZE10 sheets are characterized.The inelastic strains are generally larger under compressive Loading-Un Loading(L-UL)than under tensile L-UL,along the transverse direction(TD)than along the rolling direction(RD)under tensile L-UL,and along RD than along TD under compressive L-UL.The basal slip,twinning and de-twinning are found to be responsible for the unloading behaviors of ZE10 sheets.展开更多
The spinel LiMn2O4 used as cathode materials for lithium-ion batteries was synthesized by mechanochemistry fluid activation process, and modified by doping rare-earth Sm. Testing of X-ray diffraction, cyclic voltammog...The spinel LiMn2O4 used as cathode materials for lithium-ion batteries was synthesized by mechanochemistry fluid activation process, and modified by doping rare-earth Sm. Testing of X-ray diffraction, cyclic voltammograms, charge-discharge and SEM was carried out for LiMn2O4 cathode materials and the modified materials.The results show that the cathode materials doped rare earth LixMn2-ySmxO4 (0.95≤x≤1.2, 0≤y≤0.3, 0≤z≤0.2) exhibit standard spinel structure, high reversibility of electrochemistry and excellent properties of charge-discapacity is deteriorated less than 15% after 300 cycles at room temperature and less than 20% after 200 cycles at 55 C.At the same time, Crystal Field Theory was applied to explain the function and mechanism of doped rare earth element.展开更多
The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current ...The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.展开更多
Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive fie...Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive field and expected energy density product of a magnet made from a novel magnetic material composition.Iron(Fe)-rich magnetic phases suitable for permanent magnets can be found by means of adaptive genetic algorithms.The intrinsic properties computed by ab initio simulations are used as input for micromagnetic simulations of the hysteresis properties of permanent magnets with a realistic structure.Using machine learning techniques,the magnet’s structure can be optimized so that the upper limits for coercivity and energy density product for a given phase can be estimated.Structure property relations of synthetic permanent magnets were computed for several candidate hard magnetic phases.The following pairs(coercive field(T),energy density product(kJ·m^-3))were obtained for iron-tin-antimony(Fe3Sn0.75Sb0.25):(0.49,290),L10-ordered iron-nickel(L10 FeNi):(1,400),cobalt-iron-tantalum(CoFe6Ta):(0.87,425),and manganese-aluminum(MnAl):(0.53,80).展开更多
The magnetic phase diagram of rare-earth perovskite compound,GdScO3,has been investigated by magnetization and heat capacity.The system undergoes an antiferromagnetic phase transition at TN=2.6 K,with an easy axis of ...The magnetic phase diagram of rare-earth perovskite compound,GdScO3,has been investigated by magnetization and heat capacity.The system undergoes an antiferromagnetic phase transition at TN=2.6 K,with an easy axis of magnetization along the a axis.The magnetization measurements show that it exists a spin-flop transition around 0.3 T for the applied field along the a axis.The critical magnetic field for the antiferromagnetic-to-paramagnetic transition is near 3.2 T when temperature approaches zero.By scaling susceptibilities,we presume this point(B=3.2 T,T=0 K)might be a fieldinduced quantum critical point and the magnetic critical fluctuations can even be felt above TN.展开更多
The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray d...The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.展开更多
The rare-earth hard magnets with lower temperature coefficient, including Nd2Fe 14B/Fe3B-ferrite compound bonded magnets and Sm 0.8RE 0.2 （Co balFe 0.22Cu 0.06Zr 0.03） 7.4（RE=Gd, Er） sintered magnets, were studied...The rare-earth hard magnets with lower temperature coefficient, including Nd2Fe 14B/Fe3B-ferrite compound bonded magnets and Sm 0.8RE 0.2 （Co balFe 0.22Cu 0.06Zr 0.03） 7.4（RE=Gd, Er） sintered magnets, were studied. The result shows that the addition, that dope ferrite magnetic powder to double-phase nanocomposite Nd2Fe 14B/Fe3B magnetic powder, can make β jHc to be obviously decreased. Similarly, the effect of homogeneous heating treatment on magnetic properties was studied. Doping heavy rare earth elements to the 2∶17-type SmCo magnet material powders shows that the sintered magnets obtained lower temperature coefficient, and enhanced magnets temperature stability.展开更多
Besides W-phase and Ni-phase,there is a micro new phase in W-Mo-Ni-Fe heavy alloy added with La and Mn.The micro phase can be extracted as an electrolytic residue by the following method:A mixture of the new phase and...Besides W-phase and Ni-phase,there is a micro new phase in W-Mo-Ni-Fe heavy alloy added with La and Mn.The micro phase can be extracted as an electrolytic residue by the following method:A mixture of the new phase and the Ni-phase is isolated when an alloy sample is electrolyzed in 5% NaOH + 1% tartaric acid solution.And the new phase can be isolated alone when the mixture is electrolyzed in 10% acetylacetone + 1% LiCl methanol solution.The result of the quantitative phase analysis indicates that the new phase is a complex oxide rich in La,W and Mn.The interfacial segregation of oxygen decreases and the binding force between W-Ni phases increases because of the existence of the oxide.So the mechanical properties of the alloy are improved.展开更多
The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb onthe thermal stability of PdSi<sub>16.5</sub> glass was studied systematically by means of DSC.Allrare-earth elements,especially h...The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb onthe thermal stability of PdSi<sub>16.5</sub> glass was studied systematically by means of DSC.Allrare-earth elements,especially heavy ones,increase obviously the thermal stabilityparameters,including T<sub>θ</sub>（T<sub>g</sub> ,T<sub>x</sub> ,T<sub>g</sub>）,T<sub>rg</sub> and ΔE etc.The crystallization temperaturesT<sub>p1</sub> and T<sub>p2</sub> increase linearly with the lanthanide constriction increasing,but Eu shows ananomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and thelowest concentration limit of glass forming among Pd-Si-R glasses.展开更多
In order to improve the quality of seedlings and economic benefits,rare--earth experiments were carried out on eleven seedling-age-types of four silvicultral treespecies.Some indexes such as the increment,biomass and ...In order to improve the quality of seedlings and economic benefits,rare--earth experiments were carried out on eleven seedling-age-types of four silvicultral treespecies.Some indexes such as the increment,biomass and chlorophyl content weredetermined.The results showed that rare-earth can improve the growth in height anddiameter,increase the bioprductivity and increase the mean benefit by887766.29 yuan/hm^2.It is an effective method to improve the quality of seedlings for the characters such as lowcost and easy grasping.And the method can be widely used in seedling.展开更多
A parameter describing the solid solubilities of mre-earths in Pd, Nf/aX(TR - rPd),was proposed, where N is the fshell filled electron nutnben △X the electronegativity dtherence between Palladium and rare-earths, rR ...A parameter describing the solid solubilities of mre-earths in Pd, Nf/aX(TR - rPd),was proposed, where N is the fshell filled electron nutnben △X the electronegativity dtherence between Palladium and rare-earths, rR the atotnic radii of rare-earth elementand rPd of Pd. The marimum solid solubilities are linear relation to this parnmeterexcept La, Nd and Ce.展开更多
By using the re-derived formulae for both line-strength of electricdipole transition and simple J-mixing coefficients within the 4f shell in a rare-earthion, the spectroscopic properties of the luminescent material Eu...By using the re-derived formulae for both line-strength of electricdipole transition and simple J-mixing coefficients within the 4f shell in a rare-earthion, the spectroscopic properties of the luminescent material Eu3+ =Y2O3 and laser crystals Tb3+:=YAlO3 and Nd3+:YVO4, are investigated in detail. On the basis of three fitting Ω parameters and the effective reduced matrix elements, the spectral linestrengths, spontaneous emission probabilities, fluorescent branching ratios and lifetimeare calculated. The better agreement between theoretical results and experimental dataindicates the importance of J-mixing in the spectroscopic study of laser crystals.展开更多
基金supported by the National Natural Science Foundation of China(No.51975365)the Shanghai Pujiang Program(18PJ1405000)+1 种基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)the Province of Ontario
文摘To overcome the limitation in formability at room temperature,manufacturers have developed magnesium alloys with remarkable properties by adding rare-earth elements.The rare-earth magnesium alloys behave differently from the conventional alloys,especially with respect to their coupled anisotropic and strain rate sensitive behavior.In the current work,such behavior of the rare-earth Mg alloy ZEK100 sheet at room temperature is investigated with the aid of the elastic viscoplastic self-consistent polycrystal plasticity model.Different strain rate sensitivities(SRSs)for various deformation modes are employed by the model to simulate the strain rate sensitive behaviors under different loading directions and loading rates.Good agreement between the experiments and simulations reveals the importance and necessity of using different SRSs for each deformation mode in hexagonal close-packed metals.Furthermore,the relative activities of each deformation mode and the texture evolution during different loadings are discussed.The anisotropic and strain rate sensitive behavior is ascribed to the various operating deformation modes with different SRSs during loading along different directions.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.51775334,51821001 and 51701124)National Key Research and Development Program of China(Grant No.2016YFB0701205)+3 种基金China Postdoctoral Science Foundation(Grant No.2020M671360)Natural Science Foundation for Young of Jiangsu Province(Grant No.BK20190863)Jiangsu“Mass Innovation and Entrepreneurship”Talent Program(Shuang Chuang Ph.Ds,2018)Open Research Fund of the State Key Laboratory of Metal Matrix Composites(Grant No.sklmmc-kf18-08).
文摘During the past decades,with the increasing demands in lightweight structural materials,Mg alloys with low density and high performance have been extensively investigated and partly applied in some industries.Especially when rare earth(RE)elements are added as major alloying elements to Mg alloys,the alloy strength and creep resistance are greatly improved,which have promoted several series of Mg-RE alloys.This paper reviews the progress and developments of high-performance Mg-RE alloys in recent years with emphasis on cast alloys.The main contents include the alloy design,melt purification,grain refinement,castability,novel liquid casting and semisolid forming approaches,and the industrial applications or trials made of Mg-RE alloys.The review will provide insights for future developments of new alloys,techniques and applications of Mg alloys.
基金Supported by National Natural Science Foundation of P.R.China(50474020,60534010,60504006)
文摘Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the error compensation model of fuzzy system,is proposed to solve the prob- lem that the component content in countercurrent rare-earth extraction process is hardly measured on-line.An industry experiment in the extraction Y process by HAB using this hybrid soft-sensor proves its effectiveness.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB06020204)the National Key Basic Research and Development Program of China(Nos.2017YFC0307704,2017YFC0307600)the Marine Geological Survey Program of China Geological Survey(No.DD20160218)
文摘The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.
文摘The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.
文摘This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rareearth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments' provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr(651–1352 ppm), Ba(56–157 ppm), V(38–90 ppm),and Sr(15.1–59.6 ppm). Average values of Co and Ni were1.5 and 0.7 ppm, respectively. Trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies,typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment.^(18 )O values ranged from+ 15.4 to + 21.2% for the investigated samples, consistent with a residual material derived from chemicalweathering of felsic rock and redeposited in a sedimentary basin(typical values of + 19 to + 21.2%). While in the basin, the sediments experienced extended interactions with meteoric water enriched in d D and d16 O. However,the variation in d D and d16 O values for the investigated samples is attributed to the high temperature of formation(54–91 °C). The d D and d^(18 )O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot,tropical climatic conditions.
基金The authors gratefully acknowledge the IRT Saint-Exupery Surfinnov project partners,especially Mapaero and Prodem companies,for the financial support.
文摘The corrosion resistance of three Mg alloys containing rare-earth elements(WE43,EV31 and ZE41)was studied and compared to that of two Mg-Al alloys(AZ31 and AZ91)and of pure Mg(99.95 wt.%).Current-voltage curves and electrochemical impedance measurements were performed with rotating disk electrodes in an aerated 0.1 M Na_(2)SO_(4)solution.For all the alloys,it was confirmed that the intermetallic particles acted as local cathodes and that more protective films were formed on the alloys surface by comparison with the pure Mg.Corrosion rates were determined from inductive coupled plasma-optical emission spectroscopy measurements and from the electrochemical measurements.Higher corrosion rates were observed for the rare-earth Mg alloys compared to the AZ series alloys.These data allowed the corrosion mechanisms to be discussed.
基金Project suppoted by the National Natural Science Foundation of China(59778014)
文摘The rare-earth optical fiber is made of organic material and inorganic rare earth material.It can be used to absorb and transfer solar energy.When sunlight irradiates, it may absorb and transfer solar energy automatically; while at night or without sunlight it may give out light and play role of decoration.By utilizing high transmissivity of organic material and heat-resisting performance of inorganic material, we know the reorganization of material performance under the melting condition, and make empty core bear the high temperature of 150 ～200 ℃.When the light spreads in light guide, some light energy travels along the direction of light guide, and is introduced in the room directly.Another part of light energy is absorbed and stored by light guide, and can release light again after 8 ～ 12 h.
基金the support of the National Natural Science Foundation of China(Nos.51775337,51675331,51975365)Major Projects of the Ministry of Education(No.311017)+5 种基金the Program of Introducing Talents of Discipline to Universities(Grant No.B06012)sponsored by the Shanghai Pujiang Program(18PJ1405000)the University of Sydney-Shanghai Jiao Tong University Partnership Collaboration Awardssupported by the Natural Sciences and Engineering Research Council of Canada(Nos.RGPIN-201606464)partly supported by the Materials Genome Initiative Center,Shanghai Jiao Tong UniversityThe University of Michigan and Shanghai Jiao Tong University(UM-SJTU)joint research project(AE604401)。
文摘Due to their low symmetry in crystal structure,low elastic modulus(~45 GPa)and low yielding stress,magnesium(Mg)alloys exhibit strong inelastic behaviors during unloading.As more and more Mg alloys are developed,their unloading behaviors were less investigated,especially for rare-earth(RE)Mg alloys.In the current work,the unloading behaviors of the RE Mg alloy ZE10 sheet is carefully studied by both mechanical tests and crystal plasticity modeling.In terms of the stress-strain curves,the inelastic strain,the chord modulus,and the active deformation mechanisms,the substantial anisotropy and the loading path dependency of the unloading behaviors of ZE10 sheets are characterized.The inelastic strains are generally larger under compressive Loading-Un Loading(L-UL)than under tensile L-UL,along the transverse direction(TD)than along the rolling direction(RD)under tensile L-UL,and along RD than along TD under compressive L-UL.The basal slip,twinning and de-twinning are found to be responsible for the unloading behaviors of ZE10 sheets.
基金Project (02JJY2081) supported by the Natural Science Foundation of Hunan Province
文摘The spinel LiMn2O4 used as cathode materials for lithium-ion batteries was synthesized by mechanochemistry fluid activation process, and modified by doping rare-earth Sm. Testing of X-ray diffraction, cyclic voltammograms, charge-discharge and SEM was carried out for LiMn2O4 cathode materials and the modified materials.The results show that the cathode materials doped rare earth LixMn2-ySmxO4 (0.95≤x≤1.2, 0≤y≤0.3, 0≤z≤0.2) exhibit standard spinel structure, high reversibility of electrochemistry and excellent properties of charge-discapacity is deteriorated less than 15% after 300 cycles at room temperature and less than 20% after 200 cycles at 55 C.At the same time, Crystal Field Theory was applied to explain the function and mechanism of doped rare earth element.
基金Project supported by the National Key R&D Program of China (Grant No. 2020YFA07099003)Six Talent Peaks Project of Jiangsu Province, China (Grant No. 2019-XNY-013)a fellowship from the China Postdoctoral Science Foundation (Grant No. 2020M672181)。
文摘The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.
基金This work was supported by the EU H2020 project NOVAMAG(686056)and the Austrian Science Fund FWF(I3288-N36).Sergiu Arapan and Pablo Nieves acknowledge the European Regional Development Fund in the IT4Innovations National Supercomputing Center—path to exascale project(CZ 02.1.01/0.0/0.0/16-013/0001791)within the Operational Programme Research,Development and Education,and IT4Innovations computational resources allocated within projects OPEN-11-33,OPEN-14-23,and OPEN-17-14.
文摘Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive field and expected energy density product of a magnet made from a novel magnetic material composition.Iron(Fe)-rich magnetic phases suitable for permanent magnets can be found by means of adaptive genetic algorithms.The intrinsic properties computed by ab initio simulations are used as input for micromagnetic simulations of the hysteresis properties of permanent magnets with a realistic structure.Using machine learning techniques,the magnet’s structure can be optimized so that the upper limits for coercivity and energy density product for a given phase can be estimated.Structure property relations of synthetic permanent magnets were computed for several candidate hard magnetic phases.The following pairs(coercive field(T),energy density product(kJ·m^-3))were obtained for iron-tin-antimony(Fe3Sn0.75Sb0.25):(0.49,290),L10-ordered iron-nickel(L10 FeNi):(1,400),cobalt-iron-tantalum(CoFe6Ta):(0.87,425),and manganese-aluminum(MnAl):(0.53,80).
基金The work at SUSTech was supported by the National Natural Science Foundation of China(Grant No.11974157)Part of this work was also supported by the National Natural Science Foundation of China(Grant No.11875265)+1 种基金the Scientific Instrument Developing Project of the Chinese Academy of Sciences(3He-based neutron polarization devices)the Institute of High Energy Physics,the Chinese Academy of Sciences.Kan X C and Tian M L were supported by the National Natural Science Foundation of China(Grant No.51802002).
文摘The magnetic phase diagram of rare-earth perovskite compound,GdScO3,has been investigated by magnetization and heat capacity.The system undergoes an antiferromagnetic phase transition at TN=2.6 K,with an easy axis of magnetization along the a axis.The magnetization measurements show that it exists a spin-flop transition around 0.3 T for the applied field along the a axis.The critical magnetic field for the antiferromagnetic-to-paramagnetic transition is near 3.2 T when temperature approaches zero.By scaling susceptibilities,we presume this point(B=3.2 T,T=0 K)might be a fieldinduced quantum critical point and the magnetic critical fluctuations can even be felt above TN.
文摘The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.
文摘The rare-earth hard magnets with lower temperature coefficient, including Nd2Fe 14B/Fe3B-ferrite compound bonded magnets and Sm 0.8RE 0.2 （Co balFe 0.22Cu 0.06Zr 0.03） 7.4（RE=Gd, Er） sintered magnets, were studied. The result shows that the addition, that dope ferrite magnetic powder to double-phase nanocomposite Nd2Fe 14B/Fe3B magnetic powder, can make β jHc to be obviously decreased. Similarly, the effect of homogeneous heating treatment on magnetic properties was studied. Doping heavy rare earth elements to the 2∶17-type SmCo magnet material powders shows that the sintered magnets obtained lower temperature coefficient, and enhanced magnets temperature stability.
文摘Besides W-phase and Ni-phase,there is a micro new phase in W-Mo-Ni-Fe heavy alloy added with La and Mn.The micro phase can be extracted as an electrolytic residue by the following method:A mixture of the new phase and the Ni-phase is isolated when an alloy sample is electrolyzed in 5% NaOH + 1% tartaric acid solution.And the new phase can be isolated alone when the mixture is electrolyzed in 10% acetylacetone + 1% LiCl methanol solution.The result of the quantitative phase analysis indicates that the new phase is a complex oxide rich in La,W and Mn.The interfacial segregation of oxygen decreases and the binding force between W-Ni phases increases because of the existence of the oxide.So the mechanical properties of the alloy are improved.
文摘The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb onthe thermal stability of PdSi<sub>16.5</sub> glass was studied systematically by means of DSC.Allrare-earth elements,especially heavy ones,increase obviously the thermal stabilityparameters,including T<sub>θ</sub>（T<sub>g</sub> ,T<sub>x</sub> ,T<sub>g</sub>）,T<sub>rg</sub> and ΔE etc.The crystallization temperaturesT<sub>p1</sub> and T<sub>p2</sub> increase linearly with the lanthanide constriction increasing,but Eu shows ananomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and thelowest concentration limit of glass forming among Pd-Si-R glasses.
文摘In order to improve the quality of seedlings and economic benefits,rare--earth experiments were carried out on eleven seedling-age-types of four silvicultral treespecies.Some indexes such as the increment,biomass and chlorophyl content weredetermined.The results showed that rare-earth can improve the growth in height anddiameter,increase the bioprductivity and increase the mean benefit by887766.29 yuan/hm^2.It is an effective method to improve the quality of seedlings for the characters such as lowcost and easy grasping.And the method can be widely used in seedling.
文摘A parameter describing the solid solubilities of mre-earths in Pd, Nf/aX(TR - rPd),was proposed, where N is the fshell filled electron nutnben △X the electronegativity dtherence between Palladium and rare-earths, rR the atotnic radii of rare-earth elementand rPd of Pd. The marimum solid solubilities are linear relation to this parnmeterexcept La, Nd and Ce.
文摘By using the re-derived formulae for both line-strength of electricdipole transition and simple J-mixing coefficients within the 4f shell in a rare-earthion, the spectroscopic properties of the luminescent material Eu3+ =Y2O3 and laser crystals Tb3+:=YAlO3 and Nd3+:YVO4, are investigated in detail. On the basis of three fitting Ω parameters and the effective reduced matrix elements, the spectral linestrengths, spontaneous emission probabilities, fluorescent branching ratios and lifetimeare calculated. The better agreement between theoretical results and experimental dataindicates the importance of J-mixing in the spectroscopic study of laser crystals.
