Since 2001, China kept its position of the largest producing country of rare earth rnagnets in the world and worked on further in the global market. China exported 7,709 tons of rare earth magnets and earned foreign c...Since 2001, China kept its position of the largest producing country of rare earth rnagnets in the world and worked on further in the global market. China exported 7,709 tons of rare earth magnets and earned foreign currency ofUSS 214 million in 2004, increasing 37.2% and 33.0% over the same period of 2003 respectivety. In 2005, China exported 8.756 tons of RE magnets and earned foreign currency of USSZ39 million, up 13.9% and 11.4% over 2004 respectively.展开更多
The new component of melilite type crystal CaNdAl_(3)O_(7)(CNA)was grown by the Czochralski pulling method.Single crystal structure analysis was conducted.It is found that the CNA crystal belongs to the tetragonal sys...The new component of melilite type crystal CaNdAl_(3)O_(7)(CNA)was grown by the Czochralski pulling method.Single crystal structure analysis was conducted.It is found that the CNA crystal belongs to the tetragonal system with P-421m space group.The cell parameters a=b=0.77461 nm and c=0.51089 nm.The density and Mohs hardness of CNA crystal are 4.08 g/cm^(3) and 5.45,respectively.The specific heat of the crystal is 0.57-0.77 J/(g·K)in the temperature range of 30-300℃.X-ray photoelectron spectro scopy(XPS)shows that the crystal has stable atomic valence states and chemical environment.The vibration state of polyhedra groups in the crystal was measured by Raman spectra,and the piezoelectric response was analyzed based on the calculated results for the polyhedra polarization dipole moments.The relative dielectric permittivity of the CNA crystal at room temperature was determined to be 11.80 and the electrical resistivity was measured to be on the order of 5×10^(6)Ω·cm at 800℃.展开更多
Up-conversion(UC)luminescent materials doped with Ln^(3+)ions possess excellent optical properties and extensive applications in the formulation of multifunctional fluorescence ink.Printing technology offers various m...Up-conversion(UC)luminescent materials doped with Ln^(3+)ions possess excellent optical properties and extensive applications in the formulation of multifunctional fluorescence ink.Printing technology offers various methods for the preparation of UC fluorescent inks.This study introduced the optical properties of luminescent materials doped with Ln^(3+)ions,including luminescence characteristics and spectral characteristics,which provide a basis for the subsequent printing process.We also reviewed different printing techniques,including direct writing,screen printing,laser printing,inkjet printing,and aerosol jet printing(AJP),developed so far in the literature and explored the printing process of ink characteristics.However,the printing process of inks was explored and their potential for various applications was maximized.Therefore,the printing technology of UC fluorescent inks still faces challenges in different aspects.This review also points out the direction for future in-depth research,which is expected to promote further development and innovation in the field.展开更多
The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized...The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure.The particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 nm.The selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline nature.The samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic behavior.The Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)interaction.The doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical transition.The divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from water.The removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),respectively.The Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.展开更多
Nano phosphors of 2%Dy^(3+)(wt%)doped La_(2)MgTiO_(6) and monovalent/divalent/trivalent co-doped La_(1.98)Dy_(0.02)MgTiO_(6):x%A^(y+)(A^(y+):Li+,Ba^(2+),Sr^(2+),Bi^(3+),and Sm^(3+);0≤x≤2 wt%)were synthesized by comb...Nano phosphors of 2%Dy^(3+)(wt%)doped La_(2)MgTiO_(6) and monovalent/divalent/trivalent co-doped La_(1.98)Dy_(0.02)MgTiO_(6):x%A^(y+)(A^(y+):Li+,Ba^(2+),Sr^(2+),Bi^(3+),and Sm^(3+);0≤x≤2 wt%)were synthesized by combustion method.From the XRD data,it is deduced that an increase in the valency of co-dopant increases the crystallinity of the double perovskite orthorhombic nanocrystal structure.With an increase in co-dopant size,an elevation in optical bandgap is visible with the highest bandgap of 3.835 eV for Bi^(3+).The photo-absorption is monotonically broadened for Sr^(2+),Sm^(3+),and Li+around 200-450 nm.Under351 nm,Dy^(3+)triggered lattice shows major characteristic emission peaks at 480 nm(^(4)F_(9/2)→^(6)H_(15/2)),574 nm(^(4)F_(9/2)→^(6)H_(13/2)),and 670 nm(^(4)F_(9/2)→^(6)H_(11/2)).leading to near white light emission with CIE coordinates(0.341,0.376).Upon co-doping,the PL intensity is significantly increased with maximum emission for trivalent Sm^(3+),followed by divalent Sr^(2+)and monovalent Li+respectively.With increasing excitation wavelength,Sr^(2+)shows a dominated output and it is found that divalent Sr^(2+)is a potential codopant that could enhance luminescence intensity up to 6 times with a Sr^(2+)→Dy^(3+)energy transfer efficiency of 86%.It is specified that the CIE coordinates of Li+co-doped samples show ideal white emission with color coordinates(0.333,0.336).The concluding outcomes signify the noblest rare earth Sm^(3+)co-doping and thus Sm^(3+)→Dy^(3+)energy transfer mechanism is discussed in detail.展开更多
Based on the density functional theory,the double half-Heusler alloys LuXCo_(2)Bi_(2)(X=V,Nb,and Ta)were studied to predict their structural,thermodynamic,thermoelectric,and optical characteristics.All the considered ...Based on the density functional theory,the double half-Heusler alloys LuXCo_(2)Bi_(2)(X=V,Nb,and Ta)were studied to predict their structural,thermodynamic,thermoelectric,and optical characteristics.All the considered alloys are thermodynamically stable and have semiconductor behavior with indirect band gaps of 0.62,0.75,and 0.8 eV for LuVCo_(2)Bi_(2),LuNbCo_(2)Bi_(2),and LuTaCu_(2)Bi_(2),respectively.The investigated compounds exhibit semiconducting behavior with energy gaps below 0.8 eV.The impact of heat and pressure on thermodynamic coefficients was evaluated,and the influence of charge carriers on the temperature-dependent properties was studied using the semi-classical Boltzmann model.The studied compounds were characterized by their low lattice thermal conductivity at room temperature and low thermal expansion coefficient.These alloys exhibit substantial absorption coefficients in the ultraviolet(UV)light region,high optical conductivity,and high reflectivity in the visible light region,making them highly appealing materials for applications in the energy and electronics sectors.展开更多
Broad-band near-infrared(NIR)phosphors have garnered increasing attention due to the versatile applications in spectroscopy technology fields,but the choice of efficient NIR phosphors remains a challenge.Here,Yb^(3+)-...Broad-band near-infrared(NIR)phosphors have garnered increasing attention due to the versatile applications in spectroscopy technology fields,but the choice of efficient NIR phosphors remains a challenge.Here,Yb^(3+)-activated cubic double-perovskite tungstate Ba_(0.5)MgLaWO_(6)was synthesized using a solid-state reaction method.A broadband NIR emission(800-1150 nm)is observed from the^(2)F_(5/2)→^(2)F_(7/2)transition of Yb^(3+)activators in Ba_(0.5)MgLaWO_(6)under the excitation by UV and near-UV light.Photoluminescence(PL)spectra,decay and emission lifetimes,concentration-dependent intensities,and low temperature luminescence of Yb^(3+)-activated Ba_(0.5)MgLaWO_(6)were investigated to study the energy transfer(ET)from isolated WO_(6)polyhedra to Yb^(3+)activators.The main luminous mechanism involves cooperative energy transfer(CET),wherein,one high-energy excitation photon absorbed by host WO_(6)group converts to two NIR photons emitted by Yb^(3+).The partial substitution of MO^(6+)for W^(6+)in Ba_(0.5)MgLaWO_(6)further leads to a significant increase of the intensity and lifetime of the NIR luminescence.This work provides a feasible strategy for developing a new Yb^(3+)-doped perovskite tungstate,which demonstrates efficient wavelength down-conversion from UV and near-UV to NIR.This material could find versatile applications as an effective NIR luminescent candidate.展开更多
In this work,a series of Ce-Ti composite oxides with different Ti/Ce molar ratios was prepared by coprecipitation method,and investigated for the catalytic degradation of toluene and selective catalytic reduction of N...In this work,a series of Ce-Ti composite oxides with different Ti/Ce molar ratios was prepared by coprecipitation method,and investigated for the catalytic degradation of toluene and selective catalytic reduction of NO.The phase transition process between Ce species and Ti species is limited by modulating the interaction between Ce4+and Ti4+,while a completely amorphous composite is generated with an appropriate molar ratio of Ti/Ce(1.5/1).The catalyst CeTi1.5Oxexhibits the best catalytic performance,where the values of T90and T50for deep degradation of toluene are 297 and 330℃respectively at high weight hours space velocity(WHSV=120000 mL/(g·h)).Compared with CeO_(2),T90and T50decrease by48 and 34℃respectively while declining by 67 and 70℃compared to TiO_(2).For the SCR reaction,CeTi1.5Oxreaches 100%NO conversion at 250℃with WHSV=60000 mL/(g·h),reduced by 50℃compared to pure CeO_(2).The amorphous nanostructure with highly dispersed Ce and Ti species was confirmed by transmission electron microscopy(TEM)and X-ray diffraction(XRD)characterizations.The X-ray photoelectron spectroscopy(XPS)and Raman analyses show that a large number of active Ce-O-Ti species and surface oxygen vacancies are generated due to the strong interaction between Ti^(4+)and Ce^(4+)in CeTi_(1.5)O_(x).Additionally,H_(2)-TPR and O_(2)-TPD further confirm that the interaction promotes the low-temperature reducibility and mobility of surface-active oxygen species.Meanwhile,in-situ DRIFTS study reveals that CeTi1.5Oxwith amorphous nanostructure can dramatically enhance the dissociative and complete oxidation capacity for toluene.展开更多
Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore(WCED-REO).Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO.T...Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore(WCED-REO).Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO.The effects of pH,MgSO_(4) concentration and Al^(3+)concentration of the leaching agent solution on the column leaching behaviors of WCED-REO using magnesium sulfate were investigated.Experimental data show that controlling the MgSO_(4) concentration to 0.15 mol/L,pH of the leaching agent solution to 2,the leaching amount of aluminum from the rare earth ore gradually decreases with the increase of Al^(3+)concentration in the leaching agent solution,indicating that Al^(3+)in the leaching agent solution may act as leaching agent to participate in the ion exchange of RE3+,but the leaching amounts of rare earths change insignificantly as the Al^(3+)concentration is increased.Increasing the MgSO_(4) concentration is beneficial to the leaching of aluminum,and when the Al^(3+)concentration is 0.04 mol/L(Al accumulation),the amount of Al^(3+)leached from the rare earth ore increased gradually with increasing the MgSO_(4) concentration.The pH of the leaching agent solution has a significant influence on the leaching of aluminum in the rare earth ore,and the leaching amount of aluminum from the rare earth ore increases gradually with decreasing the pH.When the Al^(3+)conce ntration is 0.04 mol/L(Al accumulation)and the pH of the leaching agent solution is above 2.0,the aluminum in the leaching agent solution can be back-adsorbed onto the rare earth ore,and the amount of the back-adsorbed Al^(3+)increases with increasing the pH of the leaching agent solution.The injection rate of the leaching agent solution has slight effect on the leaching behavior of rare earths and aluminum.In summary,leaching of Al^(3+)and consumption of MgSO_(4) can be reduced by regulating the accumulation of aluminum,MgSO_(4) concentration and pH.展开更多
Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arra...Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arrangement of the intermolecular magnetic dipoles,magnetic blocking can be significantly enhanced.Herein manipulating the intramolecular dipole interactions by ligand modifica-tion was attempted with the use of three closely related dinuclear Er(Ⅲ)complexes of a common chemical formula of[(COT^(R))Er(μ-CI)(THF)]_(2)(COT^(R)is monosubstituted cyclooctatetraenide dianions with R=diphenylmethylsilyl(Ph_(2)MeS)for 1,triethylsilyl(TES)for 2,and triisopropylsilyl(TIPS)for 3).Each of these complexes features a centrosymmetric dinuclear core unit with their component Er(Ⅲ)ions doubly bridged by two chloro ligands and further coordinated with a capping substituted corR ligand and a coordinated THF molecule.Magnetic studies reveal that the complexes display similar ferromagnetic couplings with comparable single-molecule magnetic behaviors.The ferromagnetic couplings dominated by the intramolecular dipole interactions are found to be 0.7614,0.7380,and 0.5635 cm^(-1)for 1,2,and 3,respectively.The angles(θ)between the magnetic easy axes and the intramolecular Er-Er lines are 24.88(2)°,25.23(1),and 31.85(5),leading to transversal dipole fields of 0.0114,0.0113,and 0.0125 T for 1,2,and 3,respectively.Although the different ligand substitution generates a sizable difference of about 7 in theθangle,the resulting difference in the dipole interactions is not sufficiently strong to cause any significant differences in their magnetic properties.Further change in theθangles to the"side-by-side"(θ=90°)or"head-to-tail"(θ=0°)arrangement of the magnetic easy axes,achievable by rational mo-lecular design,is expected to lead to molecular magnetic materials with much enhanced properties.展开更多
Eu^(2+)doped fluorosilicate glass-ceramics containing BaF_(2) nanocrystals have high potential as spectral conversion materials for organic solar cells.However,it is difficult to realize the efficient design of BaF_(2...Eu^(2+)doped fluorosilicate glass-ceramics containing BaF_(2) nanocrystals have high potential as spectral conversion materials for organic solar cells.However,it is difficult to realize the efficient design of BaF_(2):Eu^(2+)doped fluorosilicate glass and to vividly observe the glass microstructure in experiment through traditional trial-and-error glass preparation method.BaF_(2):Eu^(2+)doped fluorosilicate glassceramics with high transparency,and high photoluminescence(PL)performance were predicted,designed and prepared via molecular dynamics(MD)simulation method.By MD simulation prediction,self-organized nanocrystallization was realized to inhibit the abnormal growth of nanocrystals due to[AlO_(4)]tetrahedra formed in the fluoride-oxide interface.The introduction of NaF reduces the effective phonon energy of the glass because Na+will prompt Al^(3+)to migrate from the fluoride phase to the silicate phase and interface.The local environment of Eu^(2+)is optimized by predicting the doping concentration of EuF_(3) and 2 mol%EuF3 is the best concentration in this work.Glass-ceramics sample GC2Eu as spectral conversion layer was successfully applied on organic solar cells to obtain more available visible phonons with a high photoelectric conversion efficiency(PCE).This work confirms the guidance of molecular dynamics simulation methods for fluorosilicate glasses design.展开更多
A series of isomeric sandwich-type dysprosiacarboranyl complexes,including[Na(THF)_(5)][3.2'-(THF)_(2)-3.2-Dy(1,2-C_(2)B_(9)H_(11))_(x)(1'7'-C_(2)B_(9)H_(11))_(2-x))(o/m-Dy)and[Na(THF)_(5)][2.2'-(THF)_...A series of isomeric sandwich-type dysprosiacarboranyl complexes,including[Na(THF)_(5)][3.2'-(THF)_(2)-3.2-Dy(1,2-C_(2)B_(9)H_(11))_(x)(1'7'-C_(2)B_(9)H_(11))_(2-x))(o/m-Dy)and[Na(THF)_(5)][2.2'-(THF)_(2)-2.2'-Dy(1,7-C_(2)B_(9)H_(11))2](m-Dy)were synthesized by using the isomeric dicarbollide ligands,namely[nido-7,8-C2BgH_(11)]^(2-)and[nido-7,9-C_(2)B_(9)H_(11)]^(2-).The structural details of o/m-Dy and m-Dy and magnetic dynamics of m-Dy were investigated to compare with the previous study on[Na(THF)_(5)][2.2'-(THF)_(2)-2.2'-Dy(1,2-C_(2)B_(9)H_(11))_(2)]o-Dy.The bending angles of sandwiched dysprosiacarboranes are straightened so as to improve energy bar-riers(U_(eff))from 430(5)to 591(0)K.Magneto-structural correlations show that the introduction of meta-C sites within the π-electron delocalized heterocyclic ring can effectively shorten the Dy-C_(2)B_(3)centroid distance and increase the C_(2)B_(3)centroid...Dy...C_(2)B_(3)centroid bending angle which is attributed to the dif-ferences in electronegativity between C and B atoms on the ring of C_(2)B_(3)^(2-).Therefore,to further enhance the performance of single-molecule magnets(SMMs)on this basis,future endeavors should focus on diminishing the equatorial solvent molecules to make a wider C2B3...Dy...C_(2)B_(3)bending angle.展开更多
Europium complexes are widely used as immunomarkers for lateral flow immunoassay(LFIA)because of their long luminescent lifetime,large Stokes shift,and high luminous color purity.However,most europium co mplexes exhib...Europium complexes are widely used as immunomarkers for lateral flow immunoassay(LFIA)because of their long luminescent lifetime,large Stokes shift,and high luminous color purity.However,most europium co mplexes exhibit inadequate stability in co mplex environments,and their fluorescence is readily quenched in an aqueous phase,thereby compromising the detection sensitivity and accuracy of LFIA,Herein,to ove rcome this challenge,we synthesized a polydentate europium complex,Eu(TTA)_(3)[Phen(PO-8)_(2)],characterized by robust stability.Finally,Eu(TTA)_(3)[Phen(PO-8)_(2)]was employed to fabricate polystyrene(PS)fluorescent microsphere s for LFIA,demonstrating remarrkable sensitivity and selectivity detecting serum amyloid A(SAA)at conce ntration as high as 220μg/mL,with a detection limit of 0.5μg/mL.More importantly,the SAA testing strips exhibit excellent long-term storage stability.Such stable polydentate europium complexes are anticipated to supplant existing commercial europium complexes,becoming a staple in LFIA applications.展开更多
A set of germanate garnet phosphors containing Tb^(3+)and Eu^(3+)were adequately synthesized using the high-temperature solid-state technique.The structural properties,photoluminescence characteristics,fluorescence li...A set of germanate garnet phosphors containing Tb^(3+)and Eu^(3+)were adequately synthesized using the high-temperature solid-state technique.The structural properties,photoluminescence characteristics,fluorescence lifetimes,and temperature-sensing capabilities of the phosphors were thoroughly investigated.X-ray diffraction confirms the crystalline structure of the phosphors,while photoluminescence spectra reveal a colour shift attributed to the trans fer of energy from Tb^(3+)to Eu^(3+)as the concentration of Eu^(3+)increases.The phosphors excited by UV light display a transition in colour from green to yellow,and subsequently to red,which can be used as a colour tunable phosphor in white light-emitting diode(w-LED) applications.As a novel temperature sensing material,the maximum relative sensitivity of Ca_(3)Sc_(2)Ge_(3)O_(12):Tb^(3+),Eu^(3+)phosphor is 0.1044 K-1(298 K),highlighting its potential for applications in temperature sensing.展开更多
The growing demand for luminescent nanomaterials intended for various applications increases the necessity to develop and improve approaches to the creation of highly efficient nanosized phosphors.In current study,an ...The growing demand for luminescent nanomaterials intended for various applications increases the necessity to develop and improve approaches to the creation of highly efficient nanosized phosphors.In current study,an approach to enhancing the efficiency of red luminescence of monoclinic Y_(2)O_(3):Eu^(3+)with the particle size of~20 nm by creating the oxygen-enriched environment during the gas-phase synthesis was developed.To investigate the effect of oxygen amount during the synthesis on characteristics of the phosphor,a series of nano structured Y_(2)O_(3):Eu^(3+)with the addition of 0-40 vol%O_(2) to the main buffer gas Ar was synthesized by laser vaporization.It is shown that the amount of added O_(2) exerts virtually no effect on the phase composition and particle size,but significantly improves the luminescent characteristics of Y_(2)O_(3):Eu^(3+).Thus,the addition of 30 vol%O_(2) leads to virtually a 20-fold growth in the photoluminescence(PL)intensity caused by ^(5)D_(0)→^(7)F_(0-4) transitions in Eu^(3+)and an increase in the absolute PL quantum yield from 3%to 53%(λex=395 nm)compared to the sample synthesized without O_(2).The addition of oxygen also improves the emission color coordinates from(0.571,0.320)to(0.630,0.322)due to the removal of a considerable fraction of oxygen vacancies.The synthesized nanopowders are shown to be highly stable:upon storage under ambient conditions for two years.Quantum yield(QY)of the samples decreases by less than 2%.It is expected that the key features underlying the proposed approach will be useful for various methods used to synthesize oxide nanophosphors.展开更多
This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells(SOFCs) in reducing and oxidizing atmospheres.To address this challenge,a bi-layer perovskite cer...This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells(SOFCs) in reducing and oxidizing atmospheres.To address this challenge,a bi-layer perovskite ceramic interconnect was designed by controlling the oxygen partial pressure,because of the strong correlation between the conductivity of strontium-doped lanthanum titanate(LST) and the oxygen partial pressure.The LST powder was prepared using solid-phase and sol-gel methods,and their influence on particle size and sintering behavior was compared.LST/lanthanum strontium manganite(LSM) bi-layer ceramic interconnects with varying thicknesses were fabricated through screen printing and co-sintering.The results demonstrate favorable interfacial bonding and excellent chemical compatibility between the ceramic layers.The conductivity of the bi-layer interconnect exhibits a temperature-dependent behavior,peaking at 550℃.Simulation calculations and research findings validate that the co nductivity of the bi-layer interconnect is determined by the thickness of the LSM layer and the oxygen partial pressure at the interconnect interface.Optimal conductivity is achieved with a bilayer interconnect consisting of approximately 15 μm of LST and 4 μm of LSM.This can be attributed to the efficient regulation of oxygen partial pressure at the interface,effectively mitigating LSM decomposition caused by low oxygen partial pressure and the subsequent reduction in conductivity.These results provide valuable fundamental data and methodology for the development of high-performance interconnects for tubular segmented-in-series SOFCs.展开更多
This article addresses the question of how the global and U.S.market sector allocations for rare earth elements compare.Accordingly,this article reports rare earth oxide(REO)market sector allocations,resolved by eleme...This article addresses the question of how the global and U.S.market sector allocations for rare earth elements compare.Accordingly,this article reports rare earth oxide(REO)market sector allocations,resolved by elemental profile for 2020 and reciprocally REO consumption resolved by end market use.Differences are calculated relative to 2008 and presented as percentages and as absolute tonnage.These differences encompass both changes in relative sector demand and growth rate.Historical trends,global and U.S.for REO usage by sector are calculated for the period of 2018-2022.End market sector demands,as percentages are presented,referenced to United States Geological Survey(USGS)values from 2008.Attention is given to permanent magnets and associated elements given the growing renewable generation and vehicle electrification.The criticality of Nd and Dy are considered given that they are the foundation of NdFeB permanent magnets,prominent in electric vehicle traction motors and direct drive wind turbine generators.Economic activity associated with REE market sectors is presented.Notably usage does not reflect economic value.A prime example are catalysts versus magnets.Last,vast reserves of light and heavy REEs exist in coal and coal-byproducts with potential high impact upon critical REEs and associated economics.展开更多
Phosphoric acid is a key ingredient in fertilizer production and contains many rare earth elements(REEs).Recovering REEs from phosphoric acid can prevent the accumulation of these elements in the soil and help bridge ...Phosphoric acid is a key ingredient in fertilizer production and contains many rare earth elements(REEs).Recovering REEs from phosphoric acid can prevent the accumulation of these elements in the soil and help bridge the gap between supply and demand.In this concern,a new material called Si-6G PAMAMPPAAM dendrimers modified silica gel terminated with phenylphosphonic acid-amide moieties was developed and its ability to adsorb Nd(Ⅲ)and Er(Ⅲ)from the phosphoric acid solution was investigated.K inetics and isotherm of the uptake process were investigated to explo re the so rption characte ristics.The attained results show that both metal ions exhibit the same adsorption performance,and the uptake process is depicted as a chemisorption,monolayer,uniform,and homogeneous process.The equilibrium state is achieved within 120 min,and the maximum uptake capacity is 16.7 mg Nd(Ⅲ)/g,and 14.0 mg Er(Ⅲ)/g.Sorption thermodynamics is an endothermic,spontaneous,and feasible uptake process.Nitric acid(1.0 mol/L)is found to be efficient for adsorbing about 94.3%and 92.5%of neodymium(Ⅲ)and erbium(Ⅲ)respectively,and the prepared Si-6G PAMAM-PPAAM demonstrates excellent stability over five consecutive sorption/desorption cycles.Preliminary tests on commercial phosphoric acid demonstrate that Si-6G PAMAM-PPAAM retains its effective REEs uptake from a complex comm ercial phosph oric acid solution.展开更多
Bismuth ferrite perovskite materials have recently attracted great attention because of their unique properties.In this study,Bi_(1-x)RE_(x)FeO_(3)(RE=La,Ce,Pr,Nd,Sm;x=0,0.05,0.1)thin films were deposited on glass sub...Bismuth ferrite perovskite materials have recently attracted great attention because of their unique properties.In this study,Bi_(1-x)RE_(x)FeO_(3)(RE=La,Ce,Pr,Nd,Sm;x=0,0.05,0.1)thin films were deposited on glass substrates via low-temperature sol-gel assisted spin coating procedure.It is found that in the presence of light rare-earth ions as the substitutions,the structural,morphological,and optical properties of the thin films are changed in the prepared thin films.We find that the thin films have rhombohedral structures,and from field emission scanning electron microscopy(FESEM)images,it is observed that the substitution of light rare-earth ions for Bi^(3+)affects the surface morphology and grain size of the BiFeO_(3)(BFO)thin film.Moreover,the optical properties of prepared films were investigated via UV-visible spectroscopy.For all samples,the bandgap energy values are between 1.22 and 1.65 eV.Also,the refractive index and extinction coefficient of samples are about 1.14-1.41 and 0.1-0.6,respectively.Photocatalytic properties of the samples were investigated by measuring the degradation of methylene blue(MB)dye under irradiation of sunlight.We find that the light rare-earth substituted BFO thin films have better photocatalytic activity compared to pure BiFeO_(3) thin film,the reason can be described as the band gap varied between 1.20 and 1.65 eV for different rare earth ions which directly influences the photocatalytic properties of the investigated samples.It is observed that the prepared thin films can remove between 37.18%and 69.14%of dye after 180 min of irradiation.This study confirms that prepared thin films are a suitable candidate for photocatalytic applications.展开更多
Sm and Ho were doped in Ce-Mn/TiO_(2)catalyst respectively to enhance its denitration performance at low temperature.X-ray diffraction(XRD),N2adsorption-desorption,X-ray photoelectron spectroscopy(XPS),NH3-temperature...Sm and Ho were doped in Ce-Mn/TiO_(2)catalyst respectively to enhance its denitration performance at low temperature.X-ray diffraction(XRD),N2adsorption-desorption,X-ray photoelectron spectroscopy(XPS),NH3-temperature programmed desorption(NH3-TPD),H2-temperature programmed reduction(H2-TPR)and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)techniques were used to analyze the structure and performance of catalysts.The results demonstrate that Ho doping increases the amount of acid sites and improves low temperature redox property of Ce-Mn/TiO_(2),which lead to excellent DeNOxperformance of Ho-Ce-Mn/TiO_(2)in the whole reaction temperature range.Sm doping results in decline of redox property,but it is beneficial to increasing the acid sites of Ce-Mn/TiO_(2).The increased surface acid sites and moderate oxidative ability impart Sm-Ce-Mn/TiO_(2)higher denitration activity and N2selectivity at temperature above 150℃.Lewis acid sites and redox property are the main factors affecting the activity of catalysts.Doping of Ho and Sm both improves sulfur resistance performance of Ce-Mn/TiO_(2)by inhibiting the adsorption of SO_(2)and formation of sulfate.Ce-Mn/TiO_(2)modified by Ho shows better sulfur resistance than that doped with Sm because of its more surface acid sites.展开更多
文摘Since 2001, China kept its position of the largest producing country of rare earth rnagnets in the world and worked on further in the global market. China exported 7,709 tons of rare earth magnets and earned foreign currency ofUSS 214 million in 2004, increasing 37.2% and 33.0% over the same period of 2003 respectivety. In 2005, China exported 8.756 tons of RE magnets and earned foreign currency of USSZ39 million, up 13.9% and 11.4% over 2004 respectively.
基金Project supported by the National Natural Science Foundation of China(52372008)Shandong Provincial Natural Science Foundation(ZR2020KA003,ZR2023QE165)。
文摘The new component of melilite type crystal CaNdAl_(3)O_(7)(CNA)was grown by the Czochralski pulling method.Single crystal structure analysis was conducted.It is found that the CNA crystal belongs to the tetragonal system with P-421m space group.The cell parameters a=b=0.77461 nm and c=0.51089 nm.The density and Mohs hardness of CNA crystal are 4.08 g/cm^(3) and 5.45,respectively.The specific heat of the crystal is 0.57-0.77 J/(g·K)in the temperature range of 30-300℃.X-ray photoelectron spectro scopy(XPS)shows that the crystal has stable atomic valence states and chemical environment.The vibration state of polyhedra groups in the crystal was measured by Raman spectra,and the piezoelectric response was analyzed based on the calculated results for the polyhedra polarization dipole moments.The relative dielectric permittivity of the CNA crystal at room temperature was determined to be 11.80 and the electrical resistivity was measured to be on the order of 5×10^(6)Ω·cm at 800℃.
基金Project supported by National Natural Science Foundation of China(51962006)the High-level Talents Research Initiation Project of JXUST(205200100545)+1 种基金the Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)Jiangxi Natural Science Foundation of China(20224BAB214029,20232BAB204021)。
文摘Up-conversion(UC)luminescent materials doped with Ln^(3+)ions possess excellent optical properties and extensive applications in the formulation of multifunctional fluorescence ink.Printing technology offers various methods for the preparation of UC fluorescent inks.This study introduced the optical properties of luminescent materials doped with Ln^(3+)ions,including luminescence characteristics and spectral characteristics,which provide a basis for the subsequent printing process.We also reviewed different printing techniques,including direct writing,screen printing,laser printing,inkjet printing,and aerosol jet printing(AJP),developed so far in the literature and explored the printing process of ink characteristics.However,the printing process of inks was explored and their potential for various applications was maximized.Therefore,the printing technology of UC fluorescent inks still faces challenges in different aspects.This review also points out the direction for future in-depth research,which is expected to promote further development and innovation in the field.
文摘The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion method.The X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure.The particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 nm.The selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline nature.The samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic behavior.The Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)interaction.The doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical transition.The divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from water.The removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),respectively.The Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.
文摘Nano phosphors of 2%Dy^(3+)(wt%)doped La_(2)MgTiO_(6) and monovalent/divalent/trivalent co-doped La_(1.98)Dy_(0.02)MgTiO_(6):x%A^(y+)(A^(y+):Li+,Ba^(2+),Sr^(2+),Bi^(3+),and Sm^(3+);0≤x≤2 wt%)were synthesized by combustion method.From the XRD data,it is deduced that an increase in the valency of co-dopant increases the crystallinity of the double perovskite orthorhombic nanocrystal structure.With an increase in co-dopant size,an elevation in optical bandgap is visible with the highest bandgap of 3.835 eV for Bi^(3+).The photo-absorption is monotonically broadened for Sr^(2+),Sm^(3+),and Li+around 200-450 nm.Under351 nm,Dy^(3+)triggered lattice shows major characteristic emission peaks at 480 nm(^(4)F_(9/2)→^(6)H_(15/2)),574 nm(^(4)F_(9/2)→^(6)H_(13/2)),and 670 nm(^(4)F_(9/2)→^(6)H_(11/2)).leading to near white light emission with CIE coordinates(0.341,0.376).Upon co-doping,the PL intensity is significantly increased with maximum emission for trivalent Sm^(3+),followed by divalent Sr^(2+)and monovalent Li+respectively.With increasing excitation wavelength,Sr^(2+)shows a dominated output and it is found that divalent Sr^(2+)is a potential codopant that could enhance luminescence intensity up to 6 times with a Sr^(2+)→Dy^(3+)energy transfer efficiency of 86%.It is specified that the CIE coordinates of Li+co-doped samples show ideal white emission with color coordinates(0.333,0.336).The concluding outcomes signify the noblest rare earth Sm^(3+)co-doping and thus Sm^(3+)→Dy^(3+)energy transfer mechanism is discussed in detail.
文摘Based on the density functional theory,the double half-Heusler alloys LuXCo_(2)Bi_(2)(X=V,Nb,and Ta)were studied to predict their structural,thermodynamic,thermoelectric,and optical characteristics.All the considered alloys are thermodynamically stable and have semiconductor behavior with indirect band gaps of 0.62,0.75,and 0.8 eV for LuVCo_(2)Bi_(2),LuNbCo_(2)Bi_(2),and LuTaCu_(2)Bi_(2),respectively.The investigated compounds exhibit semiconducting behavior with energy gaps below 0.8 eV.The impact of heat and pressure on thermodynamic coefficients was evaluated,and the influence of charge carriers on the temperature-dependent properties was studied using the semi-classical Boltzmann model.The studied compounds were characterized by their low lattice thermal conductivity at room temperature and low thermal expansion coefficient.These alloys exhibit substantial absorption coefficients in the ultraviolet(UV)light region,high optical conductivity,and high reflectivity in the visible light region,making them highly appealing materials for applications in the energy and electronics sectors.
基金Project supported by Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LBMHZ24F050003)Research Funds of Hangzhou Institute for Advanced Study,UCASthe Liu Zugang Expert Workstation of Yunnan Province(202205AF150076)。
文摘Broad-band near-infrared(NIR)phosphors have garnered increasing attention due to the versatile applications in spectroscopy technology fields,but the choice of efficient NIR phosphors remains a challenge.Here,Yb^(3+)-activated cubic double-perovskite tungstate Ba_(0.5)MgLaWO_(6)was synthesized using a solid-state reaction method.A broadband NIR emission(800-1150 nm)is observed from the^(2)F_(5/2)→^(2)F_(7/2)transition of Yb^(3+)activators in Ba_(0.5)MgLaWO_(6)under the excitation by UV and near-UV light.Photoluminescence(PL)spectra,decay and emission lifetimes,concentration-dependent intensities,and low temperature luminescence of Yb^(3+)-activated Ba_(0.5)MgLaWO_(6)were investigated to study the energy transfer(ET)from isolated WO_(6)polyhedra to Yb^(3+)activators.The main luminous mechanism involves cooperative energy transfer(CET),wherein,one high-energy excitation photon absorbed by host WO_(6)group converts to two NIR photons emitted by Yb^(3+).The partial substitution of MO^(6+)for W^(6+)in Ba_(0.5)MgLaWO_(6)further leads to a significant increase of the intensity and lifetime of the NIR luminescence.This work provides a feasible strategy for developing a new Yb^(3+)-doped perovskite tungstate,which demonstrates efficient wavelength down-conversion from UV and near-UV to NIR.This material could find versatile applications as an effective NIR luminescent candidate.
基金Project supported by the National Natural Science Foundation of China(22072096,22108184)。
文摘In this work,a series of Ce-Ti composite oxides with different Ti/Ce molar ratios was prepared by coprecipitation method,and investigated for the catalytic degradation of toluene and selective catalytic reduction of NO.The phase transition process between Ce species and Ti species is limited by modulating the interaction between Ce4+and Ti4+,while a completely amorphous composite is generated with an appropriate molar ratio of Ti/Ce(1.5/1).The catalyst CeTi1.5Oxexhibits the best catalytic performance,where the values of T90and T50for deep degradation of toluene are 297 and 330℃respectively at high weight hours space velocity(WHSV=120000 mL/(g·h)).Compared with CeO_(2),T90and T50decrease by48 and 34℃respectively while declining by 67 and 70℃compared to TiO_(2).For the SCR reaction,CeTi1.5Oxreaches 100%NO conversion at 250℃with WHSV=60000 mL/(g·h),reduced by 50℃compared to pure CeO_(2).The amorphous nanostructure with highly dispersed Ce and Ti species was confirmed by transmission electron microscopy(TEM)and X-ray diffraction(XRD)characterizations.The X-ray photoelectron spectroscopy(XPS)and Raman analyses show that a large number of active Ce-O-Ti species and surface oxygen vacancies are generated due to the strong interaction between Ti^(4+)and Ce^(4+)in CeTi_(1.5)O_(x).Additionally,H_(2)-TPR and O_(2)-TPD further confirm that the interaction promotes the low-temperature reducibility and mobility of surface-active oxygen species.Meanwhile,in-situ DRIFTS study reveals that CeTi1.5Oxwith amorphous nanostructure can dramatically enhance the dissociative and complete oxidation capacity for toluene.
基金Project supported by the Major Research Plan of the National Natural Science Foundation of China(91962211)the National Key Research and Development Program of China(2021YFC2902202)the Key Research and Development Program of Guangxi Province(Guike-AB22080056)。
文摘Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore(WCED-REO).Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO.The effects of pH,MgSO_(4) concentration and Al^(3+)concentration of the leaching agent solution on the column leaching behaviors of WCED-REO using magnesium sulfate were investigated.Experimental data show that controlling the MgSO_(4) concentration to 0.15 mol/L,pH of the leaching agent solution to 2,the leaching amount of aluminum from the rare earth ore gradually decreases with the increase of Al^(3+)concentration in the leaching agent solution,indicating that Al^(3+)in the leaching agent solution may act as leaching agent to participate in the ion exchange of RE3+,but the leaching amounts of rare earths change insignificantly as the Al^(3+)concentration is increased.Increasing the MgSO_(4) concentration is beneficial to the leaching of aluminum,and when the Al^(3+)concentration is 0.04 mol/L(Al accumulation),the amount of Al^(3+)leached from the rare earth ore increased gradually with increasing the MgSO_(4) concentration.The pH of the leaching agent solution has a significant influence on the leaching of aluminum in the rare earth ore,and the leaching amount of aluminum from the rare earth ore increases gradually with decreasing the pH.When the Al^(3+)conce ntration is 0.04 mol/L(Al accumulation)and the pH of the leaching agent solution is above 2.0,the aluminum in the leaching agent solution can be back-adsorbed onto the rare earth ore,and the amount of the back-adsorbed Al^(3+)increases with increasing the pH of the leaching agent solution.The injection rate of the leaching agent solution has slight effect on the leaching behavior of rare earths and aluminum.In summary,leaching of Al^(3+)and consumption of MgSO_(4) can be reduced by regulating the accumulation of aluminum,MgSO_(4) concentration and pH.
基金the National Natural Science Foundation of China(92261203,22101116,21971106)the Science Research Foun dation of jilin Province(YDZJ202301ZYTS478)。
文摘Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arrangement of the intermolecular magnetic dipoles,magnetic blocking can be significantly enhanced.Herein manipulating the intramolecular dipole interactions by ligand modifica-tion was attempted with the use of three closely related dinuclear Er(Ⅲ)complexes of a common chemical formula of[(COT^(R))Er(μ-CI)(THF)]_(2)(COT^(R)is monosubstituted cyclooctatetraenide dianions with R=diphenylmethylsilyl(Ph_(2)MeS)for 1,triethylsilyl(TES)for 2,and triisopropylsilyl(TIPS)for 3).Each of these complexes features a centrosymmetric dinuclear core unit with their component Er(Ⅲ)ions doubly bridged by two chloro ligands and further coordinated with a capping substituted corR ligand and a coordinated THF molecule.Magnetic studies reveal that the complexes display similar ferromagnetic couplings with comparable single-molecule magnetic behaviors.The ferromagnetic couplings dominated by the intramolecular dipole interactions are found to be 0.7614,0.7380,and 0.5635 cm^(-1)for 1,2,and 3,respectively.The angles(θ)between the magnetic easy axes and the intramolecular Er-Er lines are 24.88(2)°,25.23(1),and 31.85(5),leading to transversal dipole fields of 0.0114,0.0113,and 0.0125 T for 1,2,and 3,respectively.Although the different ligand substitution generates a sizable difference of about 7 in theθangle,the resulting difference in the dipole interactions is not sufficiently strong to cause any significant differences in their magnetic properties.Further change in theθangles to the"side-by-side"(θ=90°)or"head-to-tail"(θ=0°)arrangement of the magnetic easy axes,achievable by rational mo-lecular design,is expected to lead to molecular magnetic materials with much enhanced properties.
基金Project supported by the National Natural Science Foundation of China(52172008,51872255)the Key Research and Development Project of Zhejiang Province(2021C01174)。
文摘Eu^(2+)doped fluorosilicate glass-ceramics containing BaF_(2) nanocrystals have high potential as spectral conversion materials for organic solar cells.However,it is difficult to realize the efficient design of BaF_(2):Eu^(2+)doped fluorosilicate glass and to vividly observe the glass microstructure in experiment through traditional trial-and-error glass preparation method.BaF_(2):Eu^(2+)doped fluorosilicate glassceramics with high transparency,and high photoluminescence(PL)performance were predicted,designed and prepared via molecular dynamics(MD)simulation method.By MD simulation prediction,self-organized nanocrystallization was realized to inhibit the abnormal growth of nanocrystals due to[AlO_(4)]tetrahedra formed in the fluoride-oxide interface.The introduction of NaF reduces the effective phonon energy of the glass because Na+will prompt Al^(3+)to migrate from the fluoride phase to the silicate phase and interface.The local environment of Eu^(2+)is optimized by predicting the doping concentration of EuF_(3) and 2 mol%EuF3 is the best concentration in this work.Glass-ceramics sample GC2Eu as spectral conversion layer was successfully applied on organic solar cells to obtain more available visible phonons with a high photoelectric conversion efficiency(PCE).This work confirms the guidance of molecular dynamics simulation methods for fluorosilicate glasses design.
基金the National Natural Science Foundation of China(22375157)the Programme of Introducing Talents of Discipline to Universities(B23025)+4 种基金State Key Laboratory of Electrical Insulation and Power Equipment(EIPE23402,EIPE23405)SpecialSupportPlanof ShaanxiProvincefor Young Top-notch Talent,the Fundamental Research Funds for Central Universities(xtr052023002,xzy012023024)the China Postdoctoral Science Foundation(2023M742783)Shaanxi Postdoctoral Science Foundation(2023BSHYDZZ12)the"Scientists+engineers"Team Building Project of Qin Chuang Yuan(2022KXJ-088).
文摘A series of isomeric sandwich-type dysprosiacarboranyl complexes,including[Na(THF)_(5)][3.2'-(THF)_(2)-3.2-Dy(1,2-C_(2)B_(9)H_(11))_(x)(1'7'-C_(2)B_(9)H_(11))_(2-x))(o/m-Dy)and[Na(THF)_(5)][2.2'-(THF)_(2)-2.2'-Dy(1,7-C_(2)B_(9)H_(11))2](m-Dy)were synthesized by using the isomeric dicarbollide ligands,namely[nido-7,8-C2BgH_(11)]^(2-)and[nido-7,9-C_(2)B_(9)H_(11)]^(2-).The structural details of o/m-Dy and m-Dy and magnetic dynamics of m-Dy were investigated to compare with the previous study on[Na(THF)_(5)][2.2'-(THF)_(2)-2.2'-Dy(1,2-C_(2)B_(9)H_(11))_(2)]o-Dy.The bending angles of sandwiched dysprosiacarboranes are straightened so as to improve energy bar-riers(U_(eff))from 430(5)to 591(0)K.Magneto-structural correlations show that the introduction of meta-C sites within the π-electron delocalized heterocyclic ring can effectively shorten the Dy-C_(2)B_(3)centroid distance and increase the C_(2)B_(3)centroid...Dy...C_(2)B_(3)centroid bending angle which is attributed to the dif-ferences in electronegativity between C and B atoms on the ring of C_(2)B_(3)^(2-).Therefore,to further enhance the performance of single-molecule magnets(SMMs)on this basis,future endeavors should focus on diminishing the equatorial solvent molecules to make a wider C2B3...Dy...C_(2)B_(3)bending angle.
基金Project supported by the National Key R&D Program of China(2022YFF0710000)。
文摘Europium complexes are widely used as immunomarkers for lateral flow immunoassay(LFIA)because of their long luminescent lifetime,large Stokes shift,and high luminous color purity.However,most europium co mplexes exhibit inadequate stability in co mplex environments,and their fluorescence is readily quenched in an aqueous phase,thereby compromising the detection sensitivity and accuracy of LFIA,Herein,to ove rcome this challenge,we synthesized a polydentate europium complex,Eu(TTA)_(3)[Phen(PO-8)_(2)],characterized by robust stability.Finally,Eu(TTA)_(3)[Phen(PO-8)_(2)]was employed to fabricate polystyrene(PS)fluorescent microsphere s for LFIA,demonstrating remarrkable sensitivity and selectivity detecting serum amyloid A(SAA)at conce ntration as high as 220μg/mL,with a detection limit of 0.5μg/mL.More importantly,the SAA testing strips exhibit excellent long-term storage stability.Such stable polydentate europium complexes are anticipated to supplant existing commercial europium complexes,becoming a staple in LFIA applications.
基金Project supported by the National Natural Science Foundation of China (52274273)。
文摘A set of germanate garnet phosphors containing Tb^(3+)and Eu^(3+)were adequately synthesized using the high-temperature solid-state technique.The structural properties,photoluminescence characteristics,fluorescence lifetimes,and temperature-sensing capabilities of the phosphors were thoroughly investigated.X-ray diffraction confirms the crystalline structure of the phosphors,while photoluminescence spectra reveal a colour shift attributed to the trans fer of energy from Tb^(3+)to Eu^(3+)as the concentration of Eu^(3+)increases.The phosphors excited by UV light display a transition in colour from green to yellow,and subsequently to red,which can be used as a colour tunable phosphor in white light-emitting diode(w-LED) applications.As a novel temperature sensing material,the maximum relative sensitivity of Ca_(3)Sc_(2)Ge_(3)O_(12):Tb^(3+),Eu^(3+)phosphor is 0.1044 K-1(298 K),highlighting its potential for applications in temperature sensing.
基金Project supported by Russian Science Foundation(22-73-00106)partly by NIIC project(121031700313-8,M.Rakhmanova,PL kinetics study)。
文摘The growing demand for luminescent nanomaterials intended for various applications increases the necessity to develop and improve approaches to the creation of highly efficient nanosized phosphors.In current study,an approach to enhancing the efficiency of red luminescence of monoclinic Y_(2)O_(3):Eu^(3+)with the particle size of~20 nm by creating the oxygen-enriched environment during the gas-phase synthesis was developed.To investigate the effect of oxygen amount during the synthesis on characteristics of the phosphor,a series of nano structured Y_(2)O_(3):Eu^(3+)with the addition of 0-40 vol%O_(2) to the main buffer gas Ar was synthesized by laser vaporization.It is shown that the amount of added O_(2) exerts virtually no effect on the phase composition and particle size,but significantly improves the luminescent characteristics of Y_(2)O_(3):Eu^(3+).Thus,the addition of 30 vol%O_(2) leads to virtually a 20-fold growth in the photoluminescence(PL)intensity caused by ^(5)D_(0)→^(7)F_(0-4) transitions in Eu^(3+)and an increase in the absolute PL quantum yield from 3%to 53%(λex=395 nm)compared to the sample synthesized without O_(2).The addition of oxygen also improves the emission color coordinates from(0.571,0.320)to(0.630,0.322)due to the removal of a considerable fraction of oxygen vacancies.The synthesized nanopowders are shown to be highly stable:upon storage under ambient conditions for two years.Quantum yield(QY)of the samples decreases by less than 2%.It is expected that the key features underlying the proposed approach will be useful for various methods used to synthesize oxide nanophosphors.
基金Project supported by the National Key Research and Development Program of China (2021YFB4001400)。
文摘This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells(SOFCs) in reducing and oxidizing atmospheres.To address this challenge,a bi-layer perovskite ceramic interconnect was designed by controlling the oxygen partial pressure,because of the strong correlation between the conductivity of strontium-doped lanthanum titanate(LST) and the oxygen partial pressure.The LST powder was prepared using solid-phase and sol-gel methods,and their influence on particle size and sintering behavior was compared.LST/lanthanum strontium manganite(LSM) bi-layer ceramic interconnects with varying thicknesses were fabricated through screen printing and co-sintering.The results demonstrate favorable interfacial bonding and excellent chemical compatibility between the ceramic layers.The conductivity of the bi-layer interconnect exhibits a temperature-dependent behavior,peaking at 550℃.Simulation calculations and research findings validate that the co nductivity of the bi-layer interconnect is determined by the thickness of the LSM layer and the oxygen partial pressure at the interconnect interface.Optimal conductivity is achieved with a bilayer interconnect consisting of approximately 15 μm of LST and 4 μm of LSM.This can be attributed to the efficient regulation of oxygen partial pressure at the interface,effectively mitigating LSM decomposition caused by low oxygen partial pressure and the subsequent reduction in conductivity.These results provide valuable fundamental data and methodology for the development of high-performance interconnects for tubular segmented-in-series SOFCs.
基金Project supported by the United States Department of Energy,National Technology Laboratory through the NETL-Penn State University Coalition for Fossil Energy Research(UCFER 0007-PSU-DOE-6825,DE-FE0026285)。
文摘This article addresses the question of how the global and U.S.market sector allocations for rare earth elements compare.Accordingly,this article reports rare earth oxide(REO)market sector allocations,resolved by elemental profile for 2020 and reciprocally REO consumption resolved by end market use.Differences are calculated relative to 2008 and presented as percentages and as absolute tonnage.These differences encompass both changes in relative sector demand and growth rate.Historical trends,global and U.S.for REO usage by sector are calculated for the period of 2018-2022.End market sector demands,as percentages are presented,referenced to United States Geological Survey(USGS)values from 2008.Attention is given to permanent magnets and associated elements given the growing renewable generation and vehicle electrification.The criticality of Nd and Dy are considered given that they are the foundation of NdFeB permanent magnets,prominent in electric vehicle traction motors and direct drive wind turbine generators.Economic activity associated with REE market sectors is presented.Notably usage does not reflect economic value.A prime example are catalysts versus magnets.Last,vast reserves of light and heavy REEs exist in coal and coal-byproducts with potential high impact upon critical REEs and associated economics.
文摘Phosphoric acid is a key ingredient in fertilizer production and contains many rare earth elements(REEs).Recovering REEs from phosphoric acid can prevent the accumulation of these elements in the soil and help bridge the gap between supply and demand.In this concern,a new material called Si-6G PAMAMPPAAM dendrimers modified silica gel terminated with phenylphosphonic acid-amide moieties was developed and its ability to adsorb Nd(Ⅲ)and Er(Ⅲ)from the phosphoric acid solution was investigated.K inetics and isotherm of the uptake process were investigated to explo re the so rption characte ristics.The attained results show that both metal ions exhibit the same adsorption performance,and the uptake process is depicted as a chemisorption,monolayer,uniform,and homogeneous process.The equilibrium state is achieved within 120 min,and the maximum uptake capacity is 16.7 mg Nd(Ⅲ)/g,and 14.0 mg Er(Ⅲ)/g.Sorption thermodynamics is an endothermic,spontaneous,and feasible uptake process.Nitric acid(1.0 mol/L)is found to be efficient for adsorbing about 94.3%and 92.5%of neodymium(Ⅲ)and erbium(Ⅲ)respectively,and the prepared Si-6G PAMAM-PPAAM demonstrates excellent stability over five consecutive sorption/desorption cycles.Preliminary tests on commercial phosphoric acid demonstrate that Si-6G PAMAM-PPAAM retains its effective REEs uptake from a complex comm ercial phosph oric acid solution.
基金The financial support of the Research Council of Damghan University with grant number 856207。
文摘Bismuth ferrite perovskite materials have recently attracted great attention because of their unique properties.In this study,Bi_(1-x)RE_(x)FeO_(3)(RE=La,Ce,Pr,Nd,Sm;x=0,0.05,0.1)thin films were deposited on glass substrates via low-temperature sol-gel assisted spin coating procedure.It is found that in the presence of light rare-earth ions as the substitutions,the structural,morphological,and optical properties of the thin films are changed in the prepared thin films.We find that the thin films have rhombohedral structures,and from field emission scanning electron microscopy(FESEM)images,it is observed that the substitution of light rare-earth ions for Bi^(3+)affects the surface morphology and grain size of the BiFeO_(3)(BFO)thin film.Moreover,the optical properties of prepared films were investigated via UV-visible spectroscopy.For all samples,the bandgap energy values are between 1.22 and 1.65 eV.Also,the refractive index and extinction coefficient of samples are about 1.14-1.41 and 0.1-0.6,respectively.Photocatalytic properties of the samples were investigated by measuring the degradation of methylene blue(MB)dye under irradiation of sunlight.We find that the light rare-earth substituted BFO thin films have better photocatalytic activity compared to pure BiFeO_(3) thin film,the reason can be described as the band gap varied between 1.20 and 1.65 eV for different rare earth ions which directly influences the photocatalytic properties of the investigated samples.It is observed that the prepared thin films can remove between 37.18%and 69.14%of dye after 180 min of irradiation.This study confirms that prepared thin films are a suitable candidate for photocatalytic applications.
文摘Sm and Ho were doped in Ce-Mn/TiO_(2)catalyst respectively to enhance its denitration performance at low temperature.X-ray diffraction(XRD),N2adsorption-desorption,X-ray photoelectron spectroscopy(XPS),NH3-temperature programmed desorption(NH3-TPD),H2-temperature programmed reduction(H2-TPR)and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)techniques were used to analyze the structure and performance of catalysts.The results demonstrate that Ho doping increases the amount of acid sites and improves low temperature redox property of Ce-Mn/TiO_(2),which lead to excellent DeNOxperformance of Ho-Ce-Mn/TiO_(2)in the whole reaction temperature range.Sm doping results in decline of redox property,but it is beneficial to increasing the acid sites of Ce-Mn/TiO_(2).The increased surface acid sites and moderate oxidative ability impart Sm-Ce-Mn/TiO_(2)higher denitration activity and N2selectivity at temperature above 150℃.Lewis acid sites and redox property are the main factors affecting the activity of catalysts.Doping of Ho and Sm both improves sulfur resistance performance of Ce-Mn/TiO_(2)by inhibiting the adsorption of SO_(2)and formation of sulfate.Ce-Mn/TiO_(2)modified by Ho shows better sulfur resistance than that doped with Sm because of its more surface acid sites.
