The effects of mixed rare earth oxides and CaCO3 on the microstructure of an in-situ Mg2Si/Al-Si hypereutectic alloy composite were investigated by optical microscope,scanning electron microscope,and energy dispersive...The effects of mixed rare earth oxides and CaCO3 on the microstructure of an in-situ Mg2Si/Al-Si hypereutectic alloy composite were investigated by optical microscope,scanning electron microscope,and energy dispersive spectrum analysis. The results showed that the morphol-ogy of the primary Mg2Si phase particles changed from irregular or crosses to polygonal shape,their sizes decreased from 75 μm to about 25 μm,and the compound of both the oxide and CaCO3 was better than either the single mixed rare earth oxides or CaCO3.展开更多
Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible,convergent fluvial pathways(also known as rills)and the subtle nature of the less-visible,diffuse pathways(inte...Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible,convergent fluvial pathways(also known as rills)and the subtle nature of the less-visible,diffuse pathways(interrill areas).The aim of this study was to use Rare Earth Oxide(REO)tracers and Structure-from-Motion(SfM)photogrammetry to elucidate retrospective information about soil erosion rates and sediment sources during different soil erosion conditions,within a controlled laboratory environment.The experimental conditions created erosion events consistent with diffuse and convergent erosion processes.REO tracers allowed the sediment transport distances of over 2 m to be described,and helped resolved the relative contribution of diffuse and convergent soil erosion;interrill areas were also iden-tified as a significant sediment sources soil loss under convergent erosion conditions.While the potential for SfM photogrammetry to resolve sub-millimetre elevations changes was demonstrated,under some conditions non-erosional changes in surface elevation,such as compaction,exceeded volumes of soil loss via diffuse erosion.The discrepancies between SfM Photogrammetry calculations and REO tagged sediment export were beneficial,identifying that during soil erosion events sediment in both aggregate and particle form is deposited within the convergent features,even when the rill extended the full length of the soil surface.The combination of SfM photogrammetry and REO tracers has provided a novel platform for building a spatial understanding of patterns of soil loss and source apportionment between rill and interrill erosion.展开更多
A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. The effects of rare earth oxide (La2O3, CeO2, Nd2O3, Sm2O3, Eu2O3, Gd2O3 and Dy2O3) and Nd2O3 doping content on th...A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. The effects of rare earth oxide (La2O3, CeO2, Nd2O3, Sm2O3, Eu2O3, Gd2O3 and Dy2O3) and Nd2O3 doping content on the microstructure and dielectric properties of Y2Ti2O7 ceramics were investigated. The experimental results showed that the rare earth ions were considered to dissolve in Y-sites of the pyrochlore structure, different rare earth oxides and concentration had different influences on Y2Ti2O7 ceramics. It was found that the rare earth oxide could decrease dielectric loss obviously, and the τf could be adjusted to zero with proper concentration. The Y2Ti2O7 ceramics with 1 mol.% neodymium oxide(Nd2O3) added showed optimum comprehensive properties, with the sintering temperature 1450 oC, the permittivity 45, the value of Q·f 22000 GHz, and the τf value 179 ppm/ oC, while 1 mol.% Nd oxide (Nd2O3) was added.展开更多
Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sin...Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite(F)structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore(P)and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m^(-1)K^(-1)at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients(TECs)of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3×10^(-6)K^(-1) in temperature range between 200-1200℃.展开更多
Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous cataly...Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous catalysis is an effective pathway for the removal of these pollutants,and the critical issue is the development of novel and high-performance catalysts.In this review,we briefly summarize the preparation methods,physicochemical properties,catalytic activities,and related reaction mechanisms for the above pollutants removal of the rare earth oxides,mixed rare earth oxide,rare earth oxidesupported noble metal,and mixed rare earth oxide-supported noble metal catalysts that have been investigated by our group and other researchers.It was found that catalytic performance was associated with the factors,such as specific surface area,pore structure,particle size and dispersion,adsorbed oxygen species concentration,reducibility,reactant activation ability or interaction between metal nanoparticles and support.Furthermore,we also envision the development trend of such a topic in future work.展开更多
Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached...Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the nickel electrodes with flaky rare earth oxides were higher than that without rare earth oxide additives,but lower than that with normal rare earth oxide additives.The CVs experimental results suggested that flaky rare earth oxides increased the oxygen evolution potential and improved the reversibility of nickel electrodes.展开更多
Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal s...Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into the clad powder mixture to investigate the effects of RE2O3 on the in-situ carbide particle formation in Fe-based composite coatings.Through the analysis using scanning electron microscope(SEM),energy-dispersive spectroscopy(EDS) and transmission electron microscope(TEM),it was revealed that:(1) Adding RE2O3 to the Fe-based powder mixture could effectively reduce cracks and porosities and the coating surface was more smooth;(2) The solubility of carbon could be improved which increased the eutectic degree of the microstructure;(3) RE2O3 could promote the nucleation of the reinforcement particles as heterogeneous nuclei.During the precipitating process of the carbide particles,some RE2O3 powders still existed while others react with carbon in the melt to form rare earth carbides.Both of them acted as heterogeneous nuclei for the formation of particles.展开更多
Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central fi...Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central field errors caused by screening current effects,it is still a challenge for commercialization applications.In this study,the transversely isotropic constitutive relationship is selected as the mechanical model based on the structural characteristics of REBCO tapes,and suitable microelements are selected to equate the elastic constants using their average stress-strain relationships.Then,a two-dimensional axisymmetric model for coils wound by single-layer tapes is constructed to analyze the dependence of the electric-magnetic-force distribution in the tape on the strain.Finally,the anisotropic approximation of the homogenized bulk method is used to equate large-turn high-field coils,and the electric-magnetic-force distribution characteristics of the coils with/without screening effects and mechanical strain conditions are investigated,respectively.The results reveal that the mechanical strain has a weakening effect on the electromagnetic field distribution of superconducting tapes,but causes a significant enhancement in the force field distribution.In the presence of 0.5% mechanical strain,the maximum weakening of the peak value of the current density and the critical current density inside the high-field coil can reach about 8% and 13%,respectively,with a nearly 5 times increase in the peak stress.The screening current makes the current field distribution inside the coil improve by about 10 times.The screening current induced magnetic field can reach up to 0.8 T,making the relative error of the high-field coil center up to 7.8%.展开更多
Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,...Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,and a two-dimensional(2D)axisymmetric electro-magneto-thermal model is presented.The effects of the constituent materials,background field,and coil size are analyzed.An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation.The variations of the temperature and strain in superconducting layers are compared.The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation.The possible damages are discussed with the consideration of the effects of the background field and coil size.It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused.展开更多
In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3O...In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-C.For the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic one.Despite the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of REOs.Compared with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic sites.Moreover,the contents of Cu^(+) on the catalysts follow the same sequence.The reaction performance is positively related to the amount of these three types of surface sites.But metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox cycle.Furthe rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the reaction.Cu/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the catalysts.In conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.展开更多
In order to achieve a super gate dielectric performance,rare earth oxides featuring for large band gap,good thermodynamic stability and relatively high k value were selected to be laminated with TiO_(2)film to prepare...In order to achieve a super gate dielectric performance,rare earth oxides featuring for large band gap,good thermodynamic stability and relatively high k value were selected to be laminated with TiO_(2)film to prepare bilayer dielectric films.As an example,the microstructure,morphology,band gap structure and electrical performance of TiO_(2)-Y_(2)O_(3)bilayer films were systematically investigated.Results show that stacking sequence of TiO_(2)and Y_(2)O_(3)sublayers has a significant impact on the dielectric performance and Y_(2)O_(3)film as a passivation layer can effectively improve electrical properties.Besides,the electrical behaviors analysis of TiO_(2)-Y_(2)O_(3),Y_(2)O_(3)-TiO_(2),Y_(2)O_(3)and TiO_(2)samples was carried out by impedance spectra and equivale nt circuit.The result shows that TiO_(2)-Y_(2)O_(3)/Si sample holds the largest internal re sistance of 74665Ωamong four samples.Moreover,the most outstanding properties of Pt/TiO_(2)-Y_(2)O_(3)/Si capacitor are achieved by varying the thickness of sublayers and annealing temperature.500℃-annealed bilayer film with 17 nm-TiO_(2)and 3-nm Y_(2)O_(3)displays a k value of 28.24,which is more than 1.4 times that of current commercial HfO_(2).Further,Schottky emission was determined to be leakage current transport mechanism for TiO_(2)-Y_(2)O_(3)bilayer films.Inspired by this result,the electrical performance of more general Pt/TiO_(2)-REOs/Si MOS capacitors(RE=Sc,La,Ce,Gd and Pr)was measured.The combination of TiO_(2)film and REOs passivation layer with the satisfying performance provides promising candidates for future Si-based integrated circuit(IC).展开更多
As the world’s second largest economy experiencing rapid economic growth,China has a huge demand for metals and energy.In recent years,China ranks first,among all the countries in the world,in the production and cons...As the world’s second largest economy experiencing rapid economic growth,China has a huge demand for metals and energy.In recent years,China ranks first,among all the countries in the world,in the production and consumption of several metals such as copper,gold,and rare earth elements.Bioleaching,which is an approach for mining low grade and refractory ores,has been applied in industrial production,and bioleaching has made great contributions to the development of the Chinese mining industry.The exploration and application of bioleaching in China are reviewed in this study.Production and consumption trends of several metals in China over the past decade are reviewed.Technological processes at key bioleaching operations in China,such as at the Zijinshan Copper Mine and Mianhuakeng Uranium Mine,are presented.Also,the current challenges faced by bioleaching operations in China are introduced.Moreover,prospects such as efficiency improvement and environmental protection are proposed based on the current situation in the Chinese bioleaching industry.展开更多
Al2O3 and Ce-Zr mixed oxides are important components of the automobile three-way catalyst.Various contents modifying A12O3(GAL) was physically introduced into Ce-Zr-Al mixed oxides(CZA) to form series of GAL/CZA comp...Al2O3 and Ce-Zr mixed oxides are important components of the automobile three-way catalyst.Various contents modifying A12O3(GAL) was physically introduced into Ce-Zr-Al mixed oxides(CZA) to form series of GAL/CZA composition.The Pd/Rh catalyst samples were prepared by different GAL/CZA support loading Pd/Rh,then aged at 950 oC for 6 h.The catalytic behavior of different Pd/Rh catalyst samples was studied.Surface area,oxygen storage capacity(OSC) and H2 adsorption capacity(TPR) of fresh and aged samples were examined by means of BET and H2-TPR.The analysis results of surface area and chemical absorption reduction showed that GAL content in GAL/CZA composition was the main effect on surface area stability of Pd/Rh catalyst.Compared with pure CZA,CZA by mixing physically with GAL could promote the surface area and stability of Pd/Rh catalyst.On the other hand,higher OSC and OSC stability should depend on CZA content in GAL/CZA composition.Compared with pure GAL,higher CZA content in GAL/CZA can promote the OSC and OSC stability of Pd/Rh catalyst.TPR showed that the optimal range of composition(CZA>60%) could obtain high reduction activity.GAL and CZA had a synergistic effect on the surface area and OSC of catalyst.The suitable mixing ratio of GAL and CZA in GAL/CZA could simultaneously get more surface area and OSC to make better catalytic activity of Pd/Rh catalyst.展开更多
The development of efficient components to save energy plays an important role in designing of sustainable solutions. Based on the concept of green energy, gas burners based on porous ceramic structures are interestin...The development of efficient components to save energy plays an important role in designing of sustainable solutions. Based on the concept of green energy, gas burners based on porous ceramic structures are interesting technologies to supply heat and lighting by burning even low calorific fuels as biogas. In this work, perspectives on development of porous ceramic burners in Brazil are presented. For this study a mixture of rare earth oxides―yttria (YTR) was selected as raw material, considering the unique luminescence proprieties of rare earth elements. Ceramic nettings with homogeneous morphology were produced by colloidal processing of rare earth powders. The results highlighted the potentiality of these components to be applied as biogas burners.展开更多
Nickel-based alloy coatings were widely used for the remanufacturing of dies and moulds by laser cladding,but the crack sensitivity would be increase due to the higher strength and hardness,which reduced the wear resi...Nickel-based alloy coatings were widely used for the remanufacturing of dies and moulds by laser cladding,but the crack sensitivity would be increase due to the higher strength and hardness,which reduced the wear resistance of Ni-based alloys.In this paper,Ni-based coatings with the addition of a plastic phase(an austenitic stainless net)were prepared using laser cladding technology,and the CeO_(2)was added in cladding layers.The cracking mechanism,microhardness,microstructure,phase composition,and wear properties were investigated.The relationship between thermal stress and the elastic and plastic fracture had been developed from the standpoint of fracture mechan-ics and thermal elastic fracture mechanics.The fracture criterion of the nickel-based coating was obtained,and the study has shown that the crack sensitivity could be reduced by decreasing the thermal expansion coefficientΔα.Thus,a new method was proposed,which the stainless steel nets were prefabricated on the substrate.It was found that the number of cracks reduced significantly with the addition of stainless steel net.When the stainless steel net with 14 mesh was added in Ni-based coatings,the average microhardness of nickel composite coating was 565 HV_(0.2),which was 2.6 times higher than that of the 45 steel substrate.Although the rare earth oxide 4 wt.%CeO_(2)and stainless steel net were added in the Ni-based coating reducing the microhardness(the average microhardness is 425 HV_(0.2)),the wear resistance of it improved substantially.The wear volume of Ni-based composite coating was 0.56×10^(−5) mm^(3)·N^(−1)·m^(−1),which was 85.1%lower than that of 45 steel.The experiment results have shown that the Nickel-based composite coating is equipped with low crack sensitivity and high abrasive resistance with austenitic stainless net and the rare earth oxide 4 wt.%CeO2.This research offers an efficient solution to produce components with low crack susceptibility and high wear-resistance coatings fabricated by laser cladding.展开更多
The oxidation of anode carbon fuel directly affects the electrochemical performance of molten hydroxide direct carbon fuel cell(MHDCFC).In general,the anode carbon fuel can be oxidized at high temperature,thus the dir...The oxidation of anode carbon fuel directly affects the electrochemical performance of molten hydroxide direct carbon fuel cell(MHDCFC).In general,the anode carbon fuel can be oxidized at high temperature,thus the direct carbon fuel cell(DCFC)can show great electrochemical performance.In this study,rare earth oxides(La_(2)O_(3),CeO_(2),Pr_(6)O_(11))were prepared by the method of precipitation.Activated carbon was prepared by pretreatment of lignite.Rare earth oxides and activated carbon were mixed as anode carbon fuel,and rare earth oxides were used to catalyze the electrochemical oxidation of anode carbon fuel.The results show that CeO_(2)has better electrocatalytic activity compared with La_(2)O_(3)and Pr_(6)O_(11) in the MHDCFC.The electrochemical test results show that the current density(at 0.4 V)increases from 81.02 to 112.90 mA/cm^(2)and the maximum power density increases from 34.78 to 47.05 mW/cm^(2)at 450℃,when the mass fraction of CeO_(2)is increased from 0 to 40%.When the mass fraction of CeO_(2)is 30%,the current density(82.55 mA/cm^(2)at 0.4 V)at 400℃is higher than that(81.02 mA/cm^(2)at 0.4 V)without CeO_(2)at 450℃.The electrochemical oxidation mechanism of CeO_(2)catalyzed anode carbon fuel is discussed.展开更多
Solid base catalysts for the direct synthesis of dimethyl carbonate(DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K_(2)CO_(3) on the surface of La_(2)O_(3),Y_(2)O_(3),CeO2 and N...Solid base catalysts for the direct synthesis of dimethyl carbonate(DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K_(2)CO_(3) on the surface of La_(2)O_(3),Y_(2)O_(3),CeO2 and Nd_(2)O_(3).The catalysts were characterized by thermogravimetric analysis(TGA)and X-ray diffraction(XRD)techniques.The catalytic activities were efficiently influenced by the preparation conditions.The optimal loading amount of K_(2)CO_(3) is 17.6%(mass)for KCl-K_(2)CO_(3)/Y_(2)O_(3) and 22.2%for other catalysts.Supports affected the activity of catalyst.KCl-K_(2)CO_(3)/Nd_(2)O_(3) exhibited the highest activity.The activity of KCl-K_(2)CO_(3)/Y_(2)O_(3) increased with the increase of calcination temperature in the range of 800℃–900℃.The formation of KYO2,Y_(3)O_(4)Cl or YOX species probably promoted the catalysts.展开更多
The basis of the hydrophobicity of lanthanide rare earth oxides(REOs)has been the subject of considerable debate.To explore this question,the wetting behaviors and surface compositions of hierarchicallystructured Yb_(...The basis of the hydrophobicity of lanthanide rare earth oxides(REOs)has been the subject of considerable debate.To explore this question,the wetting behaviors and surface compositions of hierarchicallystructured Yb_(2)o_(3)(one of the REOs)coatings and non-REO Al_(2)o_(3)coatings deposited via solution precursor plasma spray process were investigated in this work.The Yb_(2)o_(3)coatings were subjected to a number of post-deposition treatments including vacuum(1-15 Pa)treatment,Ar-plasma treatment,heat treatment(400℃),long-time air exposure and ultra-high vacuum(1×10^(-7)Pa)treatment.Subsequent characterization showed that different post-deposition treatments resulted in different wetting behavior for the Yb_(2)o_(3)coatings which correlated with the content of hydrocarbon on the surface.Yb_(2)o_(3)coatings exhibited reversible transitions between superhydrophobicity after vacuum treatment and superhydrophilicity after Ar-plasma or heat treatment,linked to hydrocarbon adsorption onto and desorption from the surface.Yb_(2)o_(3)coatings after long-time air exposure and ultra-high vacuum treatment both remained hydrophilic and showed a smaller hydrocarbon content than coatings after vacuum treatment.Al_(2)o_(3)coatings with hierarchical surface structures similar to the Yb_(2)o_(3)coatings showed an increase in WCA to only-170 after the same vacuum treatment,indicating the REO has a much higher affinity for hydrocarbon adsorption than Al_(2)o_(3),and that the content of hydrocarbon adsorbed on the surface of the REO determined the wetting behavior.展开更多
Rare earth (RE) doped optical fibres were fabricated by using RE oxides coated silica nanoparticles. The fibre properties are comparable to those prepared by conventional techniques. The process offers better control ...Rare earth (RE) doped optical fibres were fabricated by using RE oxides coated silica nanoparticles. The fibre properties are comparable to those prepared by conventional techniques. The process offers better control over RE incorporation and homogeneity in the preform.展开更多
The present work aims to investigate the recovery of light rare earth elements(LREEs) oxides from end-oflife NiMH batteries using a hydro metallurgical process followed by effective precipitation.The operational leach...The present work aims to investigate the recovery of light rare earth elements(LREEs) oxides from end-oflife NiMH batteries using a hydro metallurgical process followed by effective precipitation.The operational leaching parameters such as phosphoric acid concentration,temperature,and the solid-liquid ratio were first optimized by Box-Behnken design.The results reveal that under optimum conditions([H_(3)PO_(4)]=2 mol/L,T=80℃,and S/L=1:10 g/mL) the leaching efficiencies of Ni,Co reach 98.1% and99.3%.While La,Ce,and Nd elements remain in the leaching residue as(La,Ce,Nd)PO_(4) with yields of 98.2%,98.6%,and 99.6% for La,Ce,and Nd,respectively.Afterward,the(La,Ce,Nd)PO_(4) is leached with HCl acid,then the rare earth oxalate was precipitated using oxalic acid at a pH of 1.8 and then the product was calcined at 800℃ for 2 h in order to synthesize the(Nd,La,Ce)_(2)O_(3).The analysis using scanning electron microscopy(SEM) coupled with energy dispersive X-ray spectroscopy(EDX) confirms the homogeneity of(Nd,La,Ce)_(2)O_(3) particles that have two morphologies,i.e.,flower and sticks with a particle size between 3and 6 μm.The unit cell parameters of(Nd,La,Ce)_(2)O_(3) were calculated after Rietveld refinement of the XRD patterns,in the space group of Fm-3m are a=b=c=0.57921 nm and the volume equal to 0.194322 nm^(3).展开更多
基金the Natural Science Foundation of Jiangxi Province (No. 0650047)the Science and Technology Program of the Education Department of Jiangxi Province,China(No.GJJ08268).
文摘The effects of mixed rare earth oxides and CaCO3 on the microstructure of an in-situ Mg2Si/Al-Si hypereutectic alloy composite were investigated by optical microscope,scanning electron microscope,and energy dispersive spectrum analysis. The results showed that the morphol-ogy of the primary Mg2Si phase particles changed from irregular or crosses to polygonal shape,their sizes decreased from 75 μm to about 25 μm,and the compound of both the oxide and CaCO3 was better than either the single mixed rare earth oxides or CaCO3.
文摘Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible,convergent fluvial pathways(also known as rills)and the subtle nature of the less-visible,diffuse pathways(interrill areas).The aim of this study was to use Rare Earth Oxide(REO)tracers and Structure-from-Motion(SfM)photogrammetry to elucidate retrospective information about soil erosion rates and sediment sources during different soil erosion conditions,within a controlled laboratory environment.The experimental conditions created erosion events consistent with diffuse and convergent erosion processes.REO tracers allowed the sediment transport distances of over 2 m to be described,and helped resolved the relative contribution of diffuse and convergent soil erosion;interrill areas were also iden-tified as a significant sediment sources soil loss under convergent erosion conditions.While the potential for SfM photogrammetry to resolve sub-millimetre elevations changes was demonstrated,under some conditions non-erosional changes in surface elevation,such as compaction,exceeded volumes of soil loss via diffuse erosion.The discrepancies between SfM Photogrammetry calculations and REO tagged sediment export were beneficial,identifying that during soil erosion events sediment in both aggregate and particle form is deposited within the convergent features,even when the rill extended the full length of the soil surface.The combination of SfM photogrammetry and REO tracers has provided a novel platform for building a spatial understanding of patterns of soil loss and source apportionment between rill and interrill erosion.
基金Project supported by the Key University Science Research Project of Jiangsu Province (08KJA430002)
文摘A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. The effects of rare earth oxide (La2O3, CeO2, Nd2O3, Sm2O3, Eu2O3, Gd2O3 and Dy2O3) and Nd2O3 doping content on the microstructure and dielectric properties of Y2Ti2O7 ceramics were investigated. The experimental results showed that the rare earth ions were considered to dissolve in Y-sites of the pyrochlore structure, different rare earth oxides and concentration had different influences on Y2Ti2O7 ceramics. It was found that the rare earth oxide could decrease dielectric loss obviously, and the τf could be adjusted to zero with proper concentration. The Y2Ti2O7 ceramics with 1 mol.% neodymium oxide(Nd2O3) added showed optimum comprehensive properties, with the sintering temperature 1450 oC, the permittivity 45, the value of Q·f 22000 GHz, and the τf value 179 ppm/ oC, while 1 mol.% Nd oxide (Nd2O3) was added.
基金supported financially by the National Natural Science Foundation of China(Nos.U1537212,51971013,51590894and 51425102)the National Key Research and Development Program of China(No.2016YFB0300901)。
文摘Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite(F)structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore(P)and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m^(-1)K^(-1)at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients(TECs)of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3×10^(-6)K^(-1) in temperature range between 200-1200℃.
基金Project supported by National Natural Science Foundation of China(21677004,21876006,21622701)National Natural Science Committee of China-Liaoning Provincial People’s Government Joint Fund(U1908204)Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal Institutions(IDHT20190503)。
文摘Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous catalysis is an effective pathway for the removal of these pollutants,and the critical issue is the development of novel and high-performance catalysts.In this review,we briefly summarize the preparation methods,physicochemical properties,catalytic activities,and related reaction mechanisms for the above pollutants removal of the rare earth oxides,mixed rare earth oxide,rare earth oxidesupported noble metal,and mixed rare earth oxide-supported noble metal catalysts that have been investigated by our group and other researchers.It was found that catalytic performance was associated with the factors,such as specific surface area,pore structure,particle size and dispersion,adsorbed oxygen species concentration,reducibility,reactant activation ability or interaction between metal nanoparticles and support.Furthermore,we also envision the development trend of such a topic in future work.
基金supported by the 863 National Research and Development Project Foundation of China (2006AA11A151)
文摘Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the nickel electrodes with flaky rare earth oxides were higher than that without rare earth oxide additives,but lower than that with normal rare earth oxide additives.The CVs experimental results suggested that flaky rare earth oxides increased the oxygen evolution potential and improved the reversibility of nickel electrodes.
文摘Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into the clad powder mixture to investigate the effects of RE2O3 on the in-situ carbide particle formation in Fe-based composite coatings.Through the analysis using scanning electron microscope(SEM),energy-dispersive spectroscopy(EDS) and transmission electron microscope(TEM),it was revealed that:(1) Adding RE2O3 to the Fe-based powder mixture could effectively reduce cracks and porosities and the coating surface was more smooth;(2) The solubility of carbon could be improved which increased the eutectic degree of the microstructure;(3) RE2O3 could promote the nucleation of the reinforcement particles as heterogeneous nuclei.During the precipitating process of the carbide particles,some RE2O3 powders still existed while others react with carbon in the melt to form rare earth carbides.Both of them acted as heterogeneous nuclei for the formation of particles.
文摘Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central field errors caused by screening current effects,it is still a challenge for commercialization applications.In this study,the transversely isotropic constitutive relationship is selected as the mechanical model based on the structural characteristics of REBCO tapes,and suitable microelements are selected to equate the elastic constants using their average stress-strain relationships.Then,a two-dimensional axisymmetric model for coils wound by single-layer tapes is constructed to analyze the dependence of the electric-magnetic-force distribution in the tape on the strain.Finally,the anisotropic approximation of the homogenized bulk method is used to equate large-turn high-field coils,and the electric-magnetic-force distribution characteristics of the coils with/without screening effects and mechanical strain conditions are investigated,respectively.The results reveal that the mechanical strain has a weakening effect on the electromagnetic field distribution of superconducting tapes,but causes a significant enhancement in the force field distribution.In the presence of 0.5% mechanical strain,the maximum weakening of the peak value of the current density and the critical current density inside the high-field coil can reach about 8% and 13%,respectively,with a nearly 5 times increase in the peak stress.The screening current makes the current field distribution inside the coil improve by about 10 times.The screening current induced magnetic field can reach up to 0.8 T,making the relative error of the high-field coil center up to 7.8%.
基金the National Natural Science Foundation of China(Nos.11872195,11472120,and 11802036)the 111 Project(No.B14044)。
文摘Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,and a two-dimensional(2D)axisymmetric electro-magneto-thermal model is presented.The effects of the constituent materials,background field,and coil size are analyzed.An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation.The variations of the temperature and strain in superconducting layers are compared.The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation.The possible damages are discussed with the consideration of the effects of the background field and coil size.It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused.
基金Project supported by the National Natural Science Foundation of China(22172071,22102069,22062013,22262021,21962009)Natural Science Foundation of Jiangxi Province,China(20202BAB203006,20212BAB203030)Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis,China(20181BCD40004).
文摘In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-C.For the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic one.Despite the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of REOs.Compared with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic sites.Moreover,the contents of Cu^(+) on the catalysts follow the same sequence.The reaction performance is positively related to the amount of these three types of surface sites.But metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox cycle.Furthe rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the reaction.Cu/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the catalysts.In conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.
基金supported by the China Postdoctoral Science Foundation (BX20200004)the National Key R&D Program of China (2017YFB0405902)the National Natural Science Foundation of China (51971004)。
文摘In order to achieve a super gate dielectric performance,rare earth oxides featuring for large band gap,good thermodynamic stability and relatively high k value were selected to be laminated with TiO_(2)film to prepare bilayer dielectric films.As an example,the microstructure,morphology,band gap structure and electrical performance of TiO_(2)-Y_(2)O_(3)bilayer films were systematically investigated.Results show that stacking sequence of TiO_(2)and Y_(2)O_(3)sublayers has a significant impact on the dielectric performance and Y_(2)O_(3)film as a passivation layer can effectively improve electrical properties.Besides,the electrical behaviors analysis of TiO_(2)-Y_(2)O_(3),Y_(2)O_(3)-TiO_(2),Y_(2)O_(3)and TiO_(2)samples was carried out by impedance spectra and equivale nt circuit.The result shows that TiO_(2)-Y_(2)O_(3)/Si sample holds the largest internal re sistance of 74665Ωamong four samples.Moreover,the most outstanding properties of Pt/TiO_(2)-Y_(2)O_(3)/Si capacitor are achieved by varying the thickness of sublayers and annealing temperature.500℃-annealed bilayer film with 17 nm-TiO_(2)and 3-nm Y_(2)O_(3)displays a k value of 28.24,which is more than 1.4 times that of current commercial HfO_(2).Further,Schottky emission was determined to be leakage current transport mechanism for TiO_(2)-Y_(2)O_(3)bilayer films.Inspired by this result,the electrical performance of more general Pt/TiO_(2)-REOs/Si MOS capacitors(RE=Sc,La,Ce,Gd and Pr)was measured.The combination of TiO_(2)film and REOs passivation layer with the satisfying performance provides promising candidates for future Si-based integrated circuit(IC).
基金This work was financially supported by the National Natural Science Foundation of China(No.52034001).
文摘As the world’s second largest economy experiencing rapid economic growth,China has a huge demand for metals and energy.In recent years,China ranks first,among all the countries in the world,in the production and consumption of several metals such as copper,gold,and rare earth elements.Bioleaching,which is an approach for mining low grade and refractory ores,has been applied in industrial production,and bioleaching has made great contributions to the development of the Chinese mining industry.The exploration and application of bioleaching in China are reviewed in this study.Production and consumption trends of several metals in China over the past decade are reviewed.Technological processes at key bioleaching operations in China,such as at the Zijinshan Copper Mine and Mianhuakeng Uranium Mine,are presented.Also,the current challenges faced by bioleaching operations in China are introduced.Moreover,prospects such as efficiency improvement and environmental protection are proposed based on the current situation in the Chinese bioleaching industry.
基金supported by the National High Technology Research and Development Program (863) of China (2006AA03Z462)
文摘Al2O3 and Ce-Zr mixed oxides are important components of the automobile three-way catalyst.Various contents modifying A12O3(GAL) was physically introduced into Ce-Zr-Al mixed oxides(CZA) to form series of GAL/CZA composition.The Pd/Rh catalyst samples were prepared by different GAL/CZA support loading Pd/Rh,then aged at 950 oC for 6 h.The catalytic behavior of different Pd/Rh catalyst samples was studied.Surface area,oxygen storage capacity(OSC) and H2 adsorption capacity(TPR) of fresh and aged samples were examined by means of BET and H2-TPR.The analysis results of surface area and chemical absorption reduction showed that GAL content in GAL/CZA composition was the main effect on surface area stability of Pd/Rh catalyst.Compared with pure CZA,CZA by mixing physically with GAL could promote the surface area and stability of Pd/Rh catalyst.On the other hand,higher OSC and OSC stability should depend on CZA content in GAL/CZA composition.Compared with pure GAL,higher CZA content in GAL/CZA can promote the OSC and OSC stability of Pd/Rh catalyst.TPR showed that the optimal range of composition(CZA>60%) could obtain high reduction activity.GAL and CZA had a synergistic effect on the surface area and OSC of catalyst.The suitable mixing ratio of GAL and CZA in GAL/CZA could simultaneously get more surface area and OSC to make better catalytic activity of Pd/Rh catalyst.
基金The State of Sao Paulo Research Foundation(FAPESP)and The National Council for Scientific and Technological Development(CNPq)for financial supportin addition,Coordination of High Degree People Improvement(CAPES)for scholarship support of the student Silas Cardoso dos Santos.
文摘The development of efficient components to save energy plays an important role in designing of sustainable solutions. Based on the concept of green energy, gas burners based on porous ceramic structures are interesting technologies to supply heat and lighting by burning even low calorific fuels as biogas. In this work, perspectives on development of porous ceramic burners in Brazil are presented. For this study a mixture of rare earth oxides―yttria (YTR) was selected as raw material, considering the unique luminescence proprieties of rare earth elements. Ceramic nettings with homogeneous morphology were produced by colloidal processing of rare earth powders. The results highlighted the potentiality of these components to be applied as biogas burners.
基金Supported by National Key R&D Program of China(Grant No.2018YFB1105100)National Natural Science Foundation of China(Grant No.51975246)+5 种基金Jilin Provincial Science and Technology Development Plan of China(Grant Nos.20190302123GX,YDZJ202101ZYTS134)the State Key Laboratory of Automotive Simulation and Control-ziyoutansuoxiangmu(202013)Interdisciplinary Research Funding Program for Doctoral Candidates of Jilin University(101832020DJX052)Science and Technology Project of Jilin Education Department(Grant No.JJKH20200958KJ)Program for JLU Science and Technology Innovative Research Team(Grant No.2019TD-34)the Advanced Manufacturing Project of Provincial School Construction of Jilin Province of China(Grant No.SXGJSF2017-2).
文摘Nickel-based alloy coatings were widely used for the remanufacturing of dies and moulds by laser cladding,but the crack sensitivity would be increase due to the higher strength and hardness,which reduced the wear resistance of Ni-based alloys.In this paper,Ni-based coatings with the addition of a plastic phase(an austenitic stainless net)were prepared using laser cladding technology,and the CeO_(2)was added in cladding layers.The cracking mechanism,microhardness,microstructure,phase composition,and wear properties were investigated.The relationship between thermal stress and the elastic and plastic fracture had been developed from the standpoint of fracture mechan-ics and thermal elastic fracture mechanics.The fracture criterion of the nickel-based coating was obtained,and the study has shown that the crack sensitivity could be reduced by decreasing the thermal expansion coefficientΔα.Thus,a new method was proposed,which the stainless steel nets were prefabricated on the substrate.It was found that the number of cracks reduced significantly with the addition of stainless steel net.When the stainless steel net with 14 mesh was added in Ni-based coatings,the average microhardness of nickel composite coating was 565 HV_(0.2),which was 2.6 times higher than that of the 45 steel substrate.Although the rare earth oxide 4 wt.%CeO_(2)and stainless steel net were added in the Ni-based coating reducing the microhardness(the average microhardness is 425 HV_(0.2)),the wear resistance of it improved substantially.The wear volume of Ni-based composite coating was 0.56×10^(−5) mm^(3)·N^(−1)·m^(−1),which was 85.1%lower than that of 45 steel.The experiment results have shown that the Nickel-based composite coating is equipped with low crack sensitivity and high abrasive resistance with austenitic stainless net and the rare earth oxide 4 wt.%CeO2.This research offers an efficient solution to produce components with low crack susceptibility and high wear-resistance coatings fabricated by laser cladding.
基金Project supported by the National Natural Science Foundation of China(21566030)。
文摘The oxidation of anode carbon fuel directly affects the electrochemical performance of molten hydroxide direct carbon fuel cell(MHDCFC).In general,the anode carbon fuel can be oxidized at high temperature,thus the direct carbon fuel cell(DCFC)can show great electrochemical performance.In this study,rare earth oxides(La_(2)O_(3),CeO_(2),Pr_(6)O_(11))were prepared by the method of precipitation.Activated carbon was prepared by pretreatment of lignite.Rare earth oxides and activated carbon were mixed as anode carbon fuel,and rare earth oxides were used to catalyze the electrochemical oxidation of anode carbon fuel.The results show that CeO_(2)has better electrocatalytic activity compared with La_(2)O_(3)and Pr_(6)O_(11) in the MHDCFC.The electrochemical test results show that the current density(at 0.4 V)increases from 81.02 to 112.90 mA/cm^(2)and the maximum power density increases from 34.78 to 47.05 mW/cm^(2)at 450℃,when the mass fraction of CeO_(2)is increased from 0 to 40%.When the mass fraction of CeO_(2)is 30%,the current density(82.55 mA/cm^(2)at 0.4 V)at 400℃is higher than that(81.02 mA/cm^(2)at 0.4 V)without CeO_(2)at 450℃.The electrochemical oxidation mechanism of CeO_(2)catalyzed anode carbon fuel is discussed.
文摘Solid base catalysts for the direct synthesis of dimethyl carbonate(DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K_(2)CO_(3) on the surface of La_(2)O_(3),Y_(2)O_(3),CeO2 and Nd_(2)O_(3).The catalysts were characterized by thermogravimetric analysis(TGA)and X-ray diffraction(XRD)techniques.The catalytic activities were efficiently influenced by the preparation conditions.The optimal loading amount of K_(2)CO_(3) is 17.6%(mass)for KCl-K_(2)CO_(3)/Y_(2)O_(3) and 22.2%for other catalysts.Supports affected the activity of catalyst.KCl-K_(2)CO_(3)/Nd_(2)O_(3) exhibited the highest activity.The activity of KCl-K_(2)CO_(3)/Y_(2)O_(3) increased with the increase of calcination temperature in the range of 800℃–900℃.The formation of KYO2,Y_(3)O_(4)Cl or YOX species probably promoted the catalysts.
基金supported by Natural Science and Engineering Research Council Canada Discovery Grants Program(No.RGPIN-2015-06377(TWC))Natural Science and Engineering Research Council Canada Green Surface Engineering for Advanced Manufacturing(Green-SEAM)Strategic Network。
文摘The basis of the hydrophobicity of lanthanide rare earth oxides(REOs)has been the subject of considerable debate.To explore this question,the wetting behaviors and surface compositions of hierarchicallystructured Yb_(2)o_(3)(one of the REOs)coatings and non-REO Al_(2)o_(3)coatings deposited via solution precursor plasma spray process were investigated in this work.The Yb_(2)o_(3)coatings were subjected to a number of post-deposition treatments including vacuum(1-15 Pa)treatment,Ar-plasma treatment,heat treatment(400℃),long-time air exposure and ultra-high vacuum(1×10^(-7)Pa)treatment.Subsequent characterization showed that different post-deposition treatments resulted in different wetting behavior for the Yb_(2)o_(3)coatings which correlated with the content of hydrocarbon on the surface.Yb_(2)o_(3)coatings exhibited reversible transitions between superhydrophobicity after vacuum treatment and superhydrophilicity after Ar-plasma or heat treatment,linked to hydrocarbon adsorption onto and desorption from the surface.Yb_(2)o_(3)coatings after long-time air exposure and ultra-high vacuum treatment both remained hydrophilic and showed a smaller hydrocarbon content than coatings after vacuum treatment.Al_(2)o_(3)coatings with hierarchical surface structures similar to the Yb_(2)o_(3)coatings showed an increase in WCA to only-170 after the same vacuum treatment,indicating the REO has a much higher affinity for hydrocarbon adsorption than Al_(2)o_(3),and that the content of hydrocarbon adsorbed on the surface of the REO determined the wetting behavior.
文摘Rare earth (RE) doped optical fibres were fabricated by using RE oxides coated silica nanoparticles. The fibre properties are comparable to those prepared by conventional techniques. The process offers better control over RE incorporation and homogeneity in the preform.
文摘The present work aims to investigate the recovery of light rare earth elements(LREEs) oxides from end-oflife NiMH batteries using a hydro metallurgical process followed by effective precipitation.The operational leaching parameters such as phosphoric acid concentration,temperature,and the solid-liquid ratio were first optimized by Box-Behnken design.The results reveal that under optimum conditions([H_(3)PO_(4)]=2 mol/L,T=80℃,and S/L=1:10 g/mL) the leaching efficiencies of Ni,Co reach 98.1% and99.3%.While La,Ce,and Nd elements remain in the leaching residue as(La,Ce,Nd)PO_(4) with yields of 98.2%,98.6%,and 99.6% for La,Ce,and Nd,respectively.Afterward,the(La,Ce,Nd)PO_(4) is leached with HCl acid,then the rare earth oxalate was precipitated using oxalic acid at a pH of 1.8 and then the product was calcined at 800℃ for 2 h in order to synthesize the(Nd,La,Ce)_(2)O_(3).The analysis using scanning electron microscopy(SEM) coupled with energy dispersive X-ray spectroscopy(EDX) confirms the homogeneity of(Nd,La,Ce)_(2)O_(3) particles that have two morphologies,i.e.,flower and sticks with a particle size between 3and 6 μm.The unit cell parameters of(Nd,La,Ce)_(2)O_(3) were calculated after Rietveld refinement of the XRD patterns,in the space group of Fm-3m are a=b=c=0.57921 nm and the volume equal to 0.194322 nm^(3).
