The development and prospect of rare earth functional biomaterials (REFB) was discussed. From 1979 to 1985, the simple REFB (salts) has been developed, and the fundamental research including forms, effects, toxicity, ...The development and prospect of rare earth functional biomaterials (REFB) was discussed. From 1979 to 1985, the simple REFB (salts) has been developed, and the fundamental research including forms, effects, toxicity, conversion in soil, and analysis methods had been finished. Then, the RE feed additive materials had been developed, and the fundamental research had also been finished. In 1990s, new REFB including RE phosphate fertilizer additive, RE conversional agricultural film additive, RE water-retraining reagent and RE seed coating reagent had been developed out rapidly. They were extended to 1.36 million hectares and big benefit had been got during the last three years. Recently, it was found that RE has some function of antagonizing heavy metals and degradating organophosphors pesticide, so the REFB will be studied as a focus once more, and will become one of the important methods of guaranteeing food security in the future.展开更多
In order to develop a highly sensitive material for nondestructive testing(NDT),(Tb_(0.3) Dy_(0.7))Fe_(1.95) thin films were deposited on FeCo substrates at room temperature by magnetron sputtering and annealed.The ma...In order to develop a highly sensitive material for nondestructive testing(NDT),(Tb_(0.3) Dy_(0.7))Fe_(1.95) thin films were deposited on FeCo substrates at room temperature by magnetron sputtering and annealed.The magnetostrictive properties and the detection efficiency of the composite films were investigated.Results demonstrate that the detection efficiency roughly shows regular consistency with the magnetostrictive strain of the TbDyFe films. Heat treatment has a great effect on the crystalline state and the magnetostrictive strain of the composite materials. The as-deposited(Tb_(0.3) Dy_(0.7))Fe_(1.95) films are amorphous, and the saturation magnetostriction(ls) is only 90 ppm. However, the nanostructured crystalline REFe2 is partially separated out in amorphous matrix after annealing at 600C for 1 h, and the ls increases to 265 ppm. Simultaneously, the detection efficiency of the composite materials is obviously improved compared to that of the as-deposited films. The detection signal of traditional FeCo strip is0.4 V at the excitation power of 1.0 P and frequency of 128 kHz and that of the strip increases significantly by depositing one layer of(Tb_(0.3) Dy_(0.7))Fe_(1.95) film. The detection signal of the composite material annealed at 600C is the best, even reaching saturation value of 2.5 V(1.0 P, 128 kHz). The results may provide us with a method for preparing new materials for NDT.展开更多
By theoretical analysis of heat transfer during the "one-step" directional solidification process, the functional relation between the temperature in solid-liquid interface and its effect factor was studied....By theoretical analysis of heat transfer during the "one-step" directional solidification process, the functional relation between the temperature in solid-liquid interface and its effect factor was studied. The thermal gradient in solid liquid interface and heat transfer coefficient between the samples and surroundings were also calculated. On the basis of the above analysis, some suggestions for improving the thermal gradient in solid-liquid interface were put forward. It will provide a theoretical instruction for preparing high performance giant magnetostrictive materials (GMM).展开更多
Progress of studies on various multi-color long afterglow luminescence materials was reviewed.Two luminescent mechanism of long afterglow behavior were discussed.Further research and development prospects about the ma...Progress of studies on various multi-color long afterglow luminescence materials was reviewed.Two luminescent mechanism of long afterglow behavior were discussed.Further research and development prospects about the materials were proposed.展开更多
With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time...With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time were investigated. TECs of the basic glass, which were heat-treated under different temperature, were also investigated. The result showed that TECs of the basic glass gradually approached a fixed value as the anneal time was extended, which suggested that most of the inner stress had been eliminated. After heat treatment, the contents of Dy2O3, Dy2Si2O7, and a new crystal increased up to 1200 ℃ and decreased below 1250 ℃, which was consistent with the TEC change of crystallized samples. This suggests that the crystal has a direct effect on TECs of the crystallized samples.展开更多
The grain boundary diffusion process(GBDP)has proven to be an effective method for enhancing the coercivity of sintered Nd-Fe-B magnets.However,the limited diffusion depth and thicker shell struc-ture have impeded the...The grain boundary diffusion process(GBDP)has proven to be an effective method for enhancing the coercivity of sintered Nd-Fe-B magnets.However,the limited diffusion depth and thicker shell struc-ture have impeded the further development of magnetic properties.Currently,the primary debates re-garding the mechanism of GBDP with Tb revolve around the dissolution-solidification mechanism and the atomic substitution mechanism.To clarify this mechanism,the microstructure evolution of sintered Nd-Fe-B magnets during the heating process of GBDP has been systematically studied by quenching at different tem peratures.In this study,it was found that the formation of TbFe_(2) phase is related to the dis-solution of _(2)Fe_(14)B grains during GBDP with Tb.The theory of mixing heat and phase separation further confirms that the Nd_(2)Fe_(14)B phase dissolves to form a mixed phase of Nd and TbFe_(2),which then solidifies into the(Nd,Tb)_(2)Fe_(14)B phase.Based on the discovery of the TbFe_(2) phase,the dissolution-solidification mechanism is considered the primary mechanism for GBDP.This is supported by the elemental content of the two typical core-shell structures observed.展开更多
This paper focuses on the preparation of rare earth oxide products from rare earth chloride solutions during the rare earth extraction and separation processes,as well as the recycling of magnesium chloride solutions....This paper focuses on the preparation of rare earth oxide products from rare earth chloride solutions during the rare earth extraction and separation processes,as well as the recycling of magnesium chloride solutions.It proposes the idea of introducing spray pyrolysis technology into the rare earth extraction and separation processes.This paper briefly describes the development history of chloride spray pyrolysis technology,focusing on the research status and application progress of rare earth chloride solution and magnesium chloride solution spray pyrolysis technology,as well as spray pyrolysis equipment.The paper also analyzes the challenges and technical intricacies associated with applying spray pyrolysis technology to chloride solutions in the rare earth extraction and separation processes.Additionally,it explores future trends and proposes strategies to facilitate the full recycling of acids and bases,streamline the process flow,and enhance the prospects for green and low-carbon rare earth metallurgy.展开更多
AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processe...AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications.Al-xSc alloys(x=5,10,15,20,25,at%)were prepared by vacuum induction melting,whose purity is mainly determined by the raw materials and the production process.The results reveal that as the Sc content increases from 5at%to 20at%,the volume fraction of the Al_(3)Sc phase in the alloy increases from 26.9%to 80.2%,and the average grain size of the Al_(3)Sc phase increases from 12.9μm to 67.7μm during this period.Additionally,both the coefficient of thermal expansion(CTE)and thermal conductivity(TC)of AlSc alloys exhibit a downward trend.Based on experimental data and first-principles calculations,the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys.The optimal characteristic parameter(k0)of the Turner model is determined to be 50.The model predictions align well with the experimental results.展开更多
Ti-Gd alloys with Gd contents of 2 wt%-8 wt% were prepared,and the influence of Gd content on the microstructure,mechanical properties,corrosion behavior,neutron absorption property and density of the alloy weas inves...Ti-Gd alloys with Gd contents of 2 wt%-8 wt% were prepared,and the influence of Gd content on the microstructure,mechanical properties,corrosion behavior,neutron absorption property and density of the alloy weas investigated.The micro structure changes from full lamellar α phase to fine equiaxed crystals,and the area fraction of Gd-rich phase decreases from 3.2% to 1.8% and then increases to 9.1%.Gd has three existing forms:pure Gd,compound oxide of Gd_(2)TiO_(5)and/or Gd_(2)O_(3)and solidifies in the Ti matrix.Ti-4Gd exhibits the best mechanical properties,its tensile strength and elongation is 102 MPa and 49%,respectively.The neutron transmittancy of Ti-8Gd alloy in water is the lowest,which is 3.75%.The corrosion rate of Ti-Gd alloy is 0.00097-0.00238 mm/a,which meets the corrosion standard of small-scale nuclear reactors and containers for spent fuel.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
The lanthanum-cerium-based slurry(LC-slurry)is extensively utilized in the chemical mechanical polishing(CMP)of TFT-LCD glass substrates,optical lenses,and other glass products.Sodium hexametaphosphate(SHMP),as a disp...The lanthanum-cerium-based slurry(LC-slurry)is extensively utilized in the chemical mechanical polishing(CMP)of TFT-LCD glass substrates,optical lenses,and other glass products.Sodium hexametaphosphate(SHMP),as a dispersant,is commonly employed to enhance the dispersion properties of LCslurry for improved polishing performance.However,the tendency of sedimentation to form a compacted sediment layer,which is challenging to redisperse,increases storage difficulty and polishing equipment failure risk,thereby limiting its utilization in CMP.In the present study,sodium carboxymethylcellulose(CMC-Na),a long-chain organic polymer,was employed to enhance the redispersibility of LC-slurry containing SHMP.A comprehensive investigation was conducted on the influence of CMC-Na dosage and slurry pH on dispersibility,redispersibility and polishing performance.Additionally,an analysis was carried out to elucidate the underlying mechanism behind the effect of CMC-Na.The study demonstrates that the LC-slurry,containing 250 ppm SHMP and 500 ppm CMC-Na,exhibits excellent dispersibility and redispersibility.Further polishing tests demonstrate that compared to the LC-slurry containing only SHMP,utilizing the slurry containing both SHMP and CMC-Na at various pH for polishing thin film transistor liquid crystal display(TFT-LCD)glass substrates results in a reduction of both material removal rate(MRR)and surface roughness(Sa).Specifically,when adjusting the slurry to a pH range of 5-6,the MRR can reach up to 330 nm/min,which closely approximates the MRR achieved by LC-slurry containing only 250 ppm SHMP at corresponding pH values.Meanwhile,after polishing,the surface roughness of the glass substrate measures approximately 0.47 nm.展开更多
The Mountain Pass mine is recognized as one of the world's primary sources of rare earth minerals.These rare earth minerals mainly consist of bastnaesite and a small amount of monazite phosphate,which cannot be de...The Mountain Pass mine is recognized as one of the world's primary sources of rare earth minerals.These rare earth minerals mainly consist of bastnaesite and a small amount of monazite phosphate,which cannot be decomposed and recovered through conventional oxidative roasting and hydrochloric acid leaching process.An efficient,clean,and economical process called the"combined method"was proposed for the utilization of the Mountain Pass mine to extract rare earths from Mountain Pass rare earth concentrate(MPREC).The main steps of this process include weak oxidation atmosphere roasting,step leaching of hydrochloric acid,solid-liquid separation,the monazite slag with sulfuric acid roasting water leaching,etc.In this paper,the roasting process of MPREC under a weak oxidation atmosphere was investigated.The study examines the thermal decomposition kinetics,phase transition process,and leaching behavior of MPREC in air/CO_(2)atmosphere.Results show that,the activation energy(Ea)for MPREC thermal decomposition in air and CO_(2)atmosphere are 146 and 320 kJ/mol,respectively.At temperature above 500℃in air or above 700℃in CO_(2)atmosphere,REOF are generated from bastnaesite through an in-situ reaction with CaO,which is decomposed from CaCO_(3),to form CaF_(2)and rare earth oxide(REO).Thus,F is regulated into solid phase.In an oxidizing atmosphere,the thermal decomposition of bastnaesite is accompanied by the rapid oxidation of Ce(Ⅲ).In co ntrast,the oxidation of Ce(Ⅲ)in a CO_(2)atmosphere is significantly inhibited.At 700℃,the oxidation rate of Ce in air is 74.09%,while in a CO_(2)atmosphere,it is only 33.83%.The hydrochloric acid leaching experiment shows that,the leaching rate of rare earth after roasting at 600℃under an air atmosphere reaches to 82.9%,and it reaches 87%after roasting at 800℃under a CO_(2)atmosphere.The reduction of Ce oxidation in a weak oxidizing atmosphere significantly improves the leaching rate of Ce.展开更多
Ion-adsorption rare earth ore(IAREO)is a crucial source of mid-heavy rare earths elements(M-HRE).Reverse osmosis technology is a promising technique for the pre-concentration of the leach solution from in-situ leachin...Ion-adsorption rare earth ore(IAREO)is a crucial source of mid-heavy rare earths elements(M-HRE).Reverse osmosis technology is a promising technique for the pre-concentration of the leach solution from in-situ leaching of IAREO.However,calcium sulfate scaling is inevitably formed in sulfate system,causing decreases in the flux and life time of membrane.Herein,to simulate the precipitation behavior of calcium sulfate in the leach solution of IAREO during reverse osmosis,a series of experiments was conducted in binary and quaternary supersaturated calcium sulfate solution systems.Experimental data show that the concentration of Ca^(2+)decreases with the increase of the concentration of Mg^(2+),and in-creases with the increase of the concentration of RE3+in both binary and quaternary systems.Whereas.the influence of Al^(3+)on the concentration of Ca^(2+)is different.This variation of the Ca^(2+)concentration is explained by thermodynamic analysis.The difference of association concentration for Mg^(2+),Al^(3+)and RE^(3+)with SO_(4)^(2-)in binary or quaternary system is the main reason.Finally,the influence and mechanisms of antiscalant on the precipitation behavior of calcium sulfate are discussed.X-ray diffraction(XRD),Zeta potential and scanning electron microscopy(SEM)analyses reveal that polyacrylic acid(PAA)effectively inhibits the crystal growth of calcium sulfate,and the precipitation time of calcium sulfate is prolonged,indicating that PPA is a potential inhibitor for calcium sulfate scaling during the process of reverse osmosis.展开更多
NO catalytic oxidation is the key performance of the diesel oxidation catalyst(DOC).We present a facile deposition method for the core-shell rare-earth manganese-zirconium composite oxide that shows the Mn mullite pha...NO catalytic oxidation is the key performance of the diesel oxidation catalyst(DOC).We present a facile deposition method for the core-shell rare-earth manganese-zirconium composite oxide that shows the Mn mullite phase uniform loading on the surface of zirconium-based composite(YMO/CYZO),which demonstrates a superior NO oxidation catalytic performance in simulated diesel combustion conditions and better thermal stability than mullite phase YMn_(2)O_(5)oxide.The NO oxidation at 250℃over YMO/CYZO-a approaches 25.2%in contrast to 13.52%over YMn_(2)O_(5)-a.Then the catalytic performance of YMO/CYZO,YMO and commercial 1 wt%Pt/Al_(2)O_(3)in a NO+O_(2)atmosphere was compared.The maximum conversion rate of YMO/CYZO to NO oxidation is 89.6%at 274℃with a GHSV of 50000 h^(-1),and the performance is superior to that of YMO(82.8%at 293℃)and 1 wt%Pt/Al_(2)O_(3)(68.6%,335℃).The NO-temperature programmed desorption(NO-TPD)and diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)results reveal that YMO/CYZO has multiple NO adsorption sites and high storage capacity.Furthermore,density functional theory(DFT)calculation indicates that YMO/CYZO has lower oxygen vacancy formation energies(E_(v)=0.93 eV)and favorable NO adsorption energies(E_(ads)=2.1 eV).Moreover,in situ X-ray photoelectron spectroscopy(XPS)characterization shows that the core-shell structure of YMO/CYZO has the potential to transmit active oxygen species to help realize Mn3+to Mn4+during the reaction process to enhance the conversion of NO*molecules,while NO oxidation reactions follow the MvK mechanism.展开更多
Replacing the oxygen evolution reaction(OER)with the anodic formaldehyde oxidation reaction(FOR)is crucial for achieving low-voltage dual-electrode hydrogen evolution.However,existing FOR catalysts face challenges suc...Replacing the oxygen evolution reaction(OER)with the anodic formaldehyde oxidation reaction(FOR)is crucial for achieving low-voltage dual-electrode hydrogen evolution.However,existing FOR catalysts face challenges such as low activity,high transition state barriers,and unclear reaction mechanisms.In this study,a three-dimensional nano-composite Cu_(2)O/Cu/Mn_(2)O_(3)heterogeneous catalyst with enhanced hydrogen spillover effect was synthesized through hydrothermal and photosensitive oxidation treatment techniques.The catalyst consists of~20 nm Cu_(2)O/Cu and 30-70 nm Mn_(2)O_(3)nanoparticles.The hydrogen spillover effect enhanced Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst demonstrated outstanding FOR performance,with an anode potential of only 0.128 V at a current density of 100 mA cm^(-2),significantly lower than that of the Cu_(2)O/Cu-CC catalyst(0.25 V)and the OER potential(1.726 V).Moreover,the Faraday efficiency of the Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst reached~100%.The electrocatalyst’s FOR performance remains stable over 50 h without decay,and its hydrogen evolution reaction(HER)performance surpasses that of Cu and MnOxelectrocatalysts.Density functional theory(DFT)calculations suggested that the Cu_(2)O/Cu/Mn_(2)O_(3)catalyst significantly lowers the energy barriers for C-H bond breaking(0.48 eV)and H-H bond formation(-0.99 eV)by promoting the hydrogen spillover effect.This study provides theoretical support for designing efficient and stable low-energy dual-electrode hydrogen evolution catalysts and validates their potential through experiments.展开更多
To achieve selective leaching of ion adsorption rare earth,it is necessary to thoroughly reveal the differences in the adsorption mechanisms of aluminum and rare earth elements.In this study,we investigated the adsorp...To achieve selective leaching of ion adsorption rare earth,it is necessary to thoroughly reveal the differences in the adsorption mechanisms of aluminum and rare earth elements.In this study,we investigated the adsorption processes of Dy and Al on the surface of K–homoionic kaolinite using batch experiments and sequential chemical extractions.The results revealed that the adsorption of Dy and Al,as well as the desorption of K,followed the Langmuir model.The maximum ion-exchangeable capacity of Dy was higher(9.39 mmol.kg^(-1))than that of Al(6.30 mmol.kg^(-1)).The ion exchange stoichiometry ratios of Dy–K and Al–K derived from the Langmuir model were2.0 and 2.6.The analysis of X-ray absorption fine structure(XAFS)and density functional theory(DFT)revealed that Dy and Al were adsorbed onto kaolinite as outer-sphere hydrated complexes via hydrogen bonds.Dy was adsorbed as[Dy(H_(2)O)_(10)]^(3+),and Al was adsorbed as[Al(OH)_(2)(H_(2)O)_(4)]^(+).In particular,the adsorption of Al resulted in protonation of the hydroxyl groups on the surface of the kaolinite.Based on the above insights,the higher ion exchange stoichiometry ratios are attributed to closer adsorption distances(6.04 A for Dy and 3.69 A for Al)and lower adsorption energies(-223.72 kJ.mol^(-1)for Dy and-268.33 kJ.mol^(-1)for Al).The maximum ionexchangeable capacity is related to the change of the surface electrical properties of kaolinite.The zeta potential was increased to-7.3 mV as the protonation resulted from aluminum adsorption,while Dy adsorption had a minor effect,maintaining a value of-17.5 m V.展开更多
This article briefly reviews the major research progress of 9 typical material fields,including rare earth luminescence materials,catalysis,rare earth materials for biomedical applications,magnetic materials,optical c...This article briefly reviews the major research progress of 9 typical material fields,including rare earth luminescence materials,catalysis,rare earth materials for biomedical applications,magnetic materials,optical crystals,molecular-based materials,energy materials,metals and alloys,as well as rare earth extraction,separation and recycling in the year 2024.The aim of the review is to summarize the past and look into the future,and it will provide a basic overview of domestic work in related fields last year.Due to the abundance of content,the review strives to be concise.展开更多
To solve the problem of ammonia wastewater pollution generated from preparing rare earth carbonate using the ammonium bicarbonate precipitation method,an eco-friendly precipitant,magnesium bicarbonate,was used to prep...To solve the problem of ammonia wastewater pollution generated from preparing rare earth carbonate using the ammonium bicarbonate precipitation method,an eco-friendly precipitant,magnesium bicarbonate,was used to prepare lanthanum cerium carbonate.The lanthanum cerium sulfate solution obtained from the smelting and separation of Baotou mixed rare earth ore was used as the raw material.The influence of pH on the content of impurities,including SO^(2-)_(4)and magnesium,and the existing states of SO^(2-)_(4)n lanthanum cerium carbonate products,as well as the thermal decomposition behavior of the products,were deeply explored.SO^(2-)_(4)mainly exists in the form of rare earth sulfate complex salts in lanthanum cerium carbonate products.The fo rmation of the salts can be effectively avoided by adjusting the pH of the precipitation process.Then the content of SO^(2-)_(4)in the product is controlled.When the pH ranges from 6.00 to 7.12,the content of SO^(2-)_(4)in the product ranges from 0.42 wt%to 0.99 wt%.The content of MgO is lower than 0.04 wt%.Both contents meet the requirements of the national standard GB/T 16479-2020.In this study,lanthanum cerium carbonate products with low-content SO^(2-)_(4)were prepared.In addition,the existing states of SO^(2-)_(4)in the products are revealed.The research provides a new method for controlling the impurity content in preparing lanthanum cerium carbonate.展开更多
This article briefly reviews the major research progress of 9 typical material fields,including rare earth luminescence materials,catalysis,rare earth materials for biomedical applications,magnetic materials,optical c...This article briefly reviews the major research progress of 9 typical material fields,including rare earth luminescence materials,catalysis,rare earth materials for biomedical applications,magnetic materials,optical crystals,molecular-based materials,energy materials,metals and alloys,as well as rare earth extraction,separation and recycling in the year 2024.The aim of the review is to summarize the past and look into the future,and it will provide a basic overview of domestic work in related fields last year.Due to the abundance of content,the review strives to be concise.展开更多
Rare earth carbonates are essential precursors for the synthesis of oxide materials.In this study,we utilized in situ monitoring equipment to explore the alterations in the crystallization during the coprecipitation s...Rare earth carbonates are essential precursors for the synthesis of oxide materials.In this study,we utilized in situ monitoring equipment to explore the alterations in the crystallization during the coprecipitation synthesis of cerium carbonate.By controlling the crystallization pathway and in the absence of any te mplating agents,we successfully synthesized a unique sphe rical self-assembled cerium oxide particle(Ceria-S).The Ceria-S exhibits excellent polishing performance.The crystallization process of cerium carbonate at 50℃persists for roughly 50 min.During the initial stages of crystallization from 0 to t_(3),the precipitated particles are amorphous.This is followed by a plateau phase of crystal growth from t_(3)to t_(5).Subsequently,during the burst crystallization phase from t_(5)to t_(6),Ce_(2)(CO_(3))_(3)·6H_(2)O and Ce_(2)O(CO_(3))_(2)·nH2O are formed,exhibiting a rod-like crystal morphology.By rapidly drying the precipitated particles at 60℃for 10 min and calcining,Ceria-S is obtained.The Ceria-S,with an average diameter of 180 nm,is assembled from primary cerium oxide nanoparticles of approximately 15 nm.Owing to the self-assembly structure of cerium oxide spherical nanoparticles,they exhibit a significantly larger specific surface area,resulting in an elevated concentration of Ce^(3+)as high as 35.5%.The Ceria-S exhibits a polishing removal rate of 420 nm/min,effectively decreasing the surface roughness(S_(a))of K9 glass from 1.605 to 0.404 nm.展开更多
文摘The development and prospect of rare earth functional biomaterials (REFB) was discussed. From 1979 to 1985, the simple REFB (salts) has been developed, and the fundamental research including forms, effects, toxicity, conversion in soil, and analysis methods had been finished. Then, the RE feed additive materials had been developed, and the fundamental research had also been finished. In 1990s, new REFB including RE phosphate fertilizer additive, RE conversional agricultural film additive, RE water-retraining reagent and RE seed coating reagent had been developed out rapidly. They were extended to 1.36 million hectares and big benefit had been got during the last three years. Recently, it was found that RE has some function of antagonizing heavy metals and degradating organophosphors pesticide, so the REFB will be studied as a focus once more, and will become one of the important methods of guaranteeing food security in the future.
基金Project supported by the National Natural Science Foundation of China(51501016)
文摘In order to develop a highly sensitive material for nondestructive testing(NDT),(Tb_(0.3) Dy_(0.7))Fe_(1.95) thin films were deposited on FeCo substrates at room temperature by magnetron sputtering and annealed.The magnetostrictive properties and the detection efficiency of the composite films were investigated.Results demonstrate that the detection efficiency roughly shows regular consistency with the magnetostrictive strain of the TbDyFe films. Heat treatment has a great effect on the crystalline state and the magnetostrictive strain of the composite materials. The as-deposited(Tb_(0.3) Dy_(0.7))Fe_(1.95) films are amorphous, and the saturation magnetostriction(ls) is only 90 ppm. However, the nanostructured crystalline REFe2 is partially separated out in amorphous matrix after annealing at 600C for 1 h, and the ls increases to 265 ppm. Simultaneously, the detection efficiency of the composite materials is obviously improved compared to that of the as-deposited films. The detection signal of traditional FeCo strip is0.4 V at the excitation power of 1.0 P and frequency of 128 kHz and that of the strip increases significantly by depositing one layer of(Tb_(0.3) Dy_(0.7))Fe_(1.95) film. The detection signal of the composite material annealed at 600C is the best, even reaching saturation value of 2.5 V(1.0 P, 128 kHz). The results may provide us with a method for preparing new materials for NDT.
基金This project was supported by the Natural Science Foundation of Beijing (2042012)
文摘By theoretical analysis of heat transfer during the "one-step" directional solidification process, the functional relation between the temperature in solid-liquid interface and its effect factor was studied. The thermal gradient in solid liquid interface and heat transfer coefficient between the samples and surroundings were also calculated. On the basis of the above analysis, some suggestions for improving the thermal gradient in solid-liquid interface were put forward. It will provide a theoretical instruction for preparing high performance giant magnetostrictive materials (GMM).
文摘Progress of studies on various multi-color long afterglow luminescence materials was reviewed.Two luminescent mechanism of long afterglow behavior were discussed.Further research and development prospects about the materials were proposed.
基金Project supported by the Ministry of Science and Technology of China (2006CB601104)
文摘With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time were investigated. TECs of the basic glass, which were heat-treated under different temperature, were also investigated. The result showed that TECs of the basic glass gradually approached a fixed value as the anneal time was extended, which suggested that most of the inner stress had been eliminated. After heat treatment, the contents of Dy2O3, Dy2Si2O7, and a new crystal increased up to 1200 ℃ and decreased below 1250 ℃, which was consistent with the TEC change of crystallized samples. This suggests that the crystal has a direct effect on TECs of the crystallized samples.
基金supported by the National Key Research and Development Program of China(2022YFB3505503)the National Natural Science Foundation of China(52201230)+2 种基金the Key R&D Program of Shandong Province(2022CXGC020307)the China Postdoctoral Science Foundation(2022M71204)the Beijing NOVA Program(Z211100002121092).
文摘The grain boundary diffusion process(GBDP)has proven to be an effective method for enhancing the coercivity of sintered Nd-Fe-B magnets.However,the limited diffusion depth and thicker shell struc-ture have impeded the further development of magnetic properties.Currently,the primary debates re-garding the mechanism of GBDP with Tb revolve around the dissolution-solidification mechanism and the atomic substitution mechanism.To clarify this mechanism,the microstructure evolution of sintered Nd-Fe-B magnets during the heating process of GBDP has been systematically studied by quenching at different tem peratures.In this study,it was found that the formation of TbFe_(2) phase is related to the dis-solution of _(2)Fe_(14)B grains during GBDP with Tb.The theory of mixing heat and phase separation further confirms that the Nd_(2)Fe_(14)B phase dissolves to form a mixed phase of Nd and TbFe_(2),which then solidifies into the(Nd,Tb)_(2)Fe_(14)B phase.Based on the discovery of the TbFe_(2) phase,the dissolution-solidification mechanism is considered the primary mechanism for GBDP.This is supported by the elemental content of the two typical core-shell structures observed.
基金supported by the National Key Research and Development Program of China(2022YFB3504501)the National Natural Science Foundation of China(52274355)。
文摘This paper focuses on the preparation of rare earth oxide products from rare earth chloride solutions during the rare earth extraction and separation processes,as well as the recycling of magnesium chloride solutions.It proposes the idea of introducing spray pyrolysis technology into the rare earth extraction and separation processes.This paper briefly describes the development history of chloride spray pyrolysis technology,focusing on the research status and application progress of rare earth chloride solution and magnesium chloride solution spray pyrolysis technology,as well as spray pyrolysis equipment.The paper also analyzes the challenges and technical intricacies associated with applying spray pyrolysis technology to chloride solutions in the rare earth extraction and separation processes.Additionally,it explores future trends and proposes strategies to facilitate the full recycling of acids and bases,streamline the process flow,and enhance the prospects for green and low-carbon rare earth metallurgy.
基金National Key Research and Development Program of China(2022YFB3504402,2023YFB3610101)。
文摘AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications.Al-xSc alloys(x=5,10,15,20,25,at%)were prepared by vacuum induction melting,whose purity is mainly determined by the raw materials and the production process.The results reveal that as the Sc content increases from 5at%to 20at%,the volume fraction of the Al_(3)Sc phase in the alloy increases from 26.9%to 80.2%,and the average grain size of the Al_(3)Sc phase increases from 12.9μm to 67.7μm during this period.Additionally,both the coefficient of thermal expansion(CTE)and thermal conductivity(TC)of AlSc alloys exhibit a downward trend.Based on experimental data and first-principles calculations,the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys.The optimal characteristic parameter(k0)of the Turner model is determined to be 50.The model predictions align well with the experimental results.
基金Project supported by the National Key R&D Program of China (2023YFB3506703)。
文摘Ti-Gd alloys with Gd contents of 2 wt%-8 wt% were prepared,and the influence of Gd content on the microstructure,mechanical properties,corrosion behavior,neutron absorption property and density of the alloy weas investigated.The micro structure changes from full lamellar α phase to fine equiaxed crystals,and the area fraction of Gd-rich phase decreases from 3.2% to 1.8% and then increases to 9.1%.Gd has three existing forms:pure Gd,compound oxide of Gd_(2)TiO_(5)and/or Gd_(2)O_(3)and solidifies in the Ti matrix.Ti-4Gd exhibits the best mechanical properties,its tensile strength and elongation is 102 MPa and 49%,respectively.The neutron transmittancy of Ti-8Gd alloy in water is the lowest,which is 3.75%.The corrosion rate of Ti-Gd alloy is 0.00097-0.00238 mm/a,which meets the corrosion standard of small-scale nuclear reactors and containers for spent fuel.
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supported by the National Key Research and Development Program(2021YFB3501103)Guiding Local Funding Projects for Scientific and Technological Development by Central Government in Hebei(216Z1402G)Youth Fund of GRINM Group Co.,Ltd.
文摘The lanthanum-cerium-based slurry(LC-slurry)is extensively utilized in the chemical mechanical polishing(CMP)of TFT-LCD glass substrates,optical lenses,and other glass products.Sodium hexametaphosphate(SHMP),as a dispersant,is commonly employed to enhance the dispersion properties of LCslurry for improved polishing performance.However,the tendency of sedimentation to form a compacted sediment layer,which is challenging to redisperse,increases storage difficulty and polishing equipment failure risk,thereby limiting its utilization in CMP.In the present study,sodium carboxymethylcellulose(CMC-Na),a long-chain organic polymer,was employed to enhance the redispersibility of LC-slurry containing SHMP.A comprehensive investigation was conducted on the influence of CMC-Na dosage and slurry pH on dispersibility,redispersibility and polishing performance.Additionally,an analysis was carried out to elucidate the underlying mechanism behind the effect of CMC-Na.The study demonstrates that the LC-slurry,containing 250 ppm SHMP and 500 ppm CMC-Na,exhibits excellent dispersibility and redispersibility.Further polishing tests demonstrate that compared to the LC-slurry containing only SHMP,utilizing the slurry containing both SHMP and CMC-Na at various pH for polishing thin film transistor liquid crystal display(TFT-LCD)glass substrates results in a reduction of both material removal rate(MRR)and surface roughness(Sa).Specifically,when adjusting the slurry to a pH range of 5-6,the MRR can reach up to 330 nm/min,which closely approximates the MRR achieved by LC-slurry containing only 250 ppm SHMP at corresponding pH values.Meanwhile,after polishing,the surface roughness of the glass substrate measures approximately 0.47 nm.
基金supported by the National Key Research and Development Program of China(2020YFC1909104)National Natural Science Foundation of China(52274355)Major Science and Technology Project of Inner Mongolia Autonomous Region(2021ZD0016)。
文摘The Mountain Pass mine is recognized as one of the world's primary sources of rare earth minerals.These rare earth minerals mainly consist of bastnaesite and a small amount of monazite phosphate,which cannot be decomposed and recovered through conventional oxidative roasting and hydrochloric acid leaching process.An efficient,clean,and economical process called the"combined method"was proposed for the utilization of the Mountain Pass mine to extract rare earths from Mountain Pass rare earth concentrate(MPREC).The main steps of this process include weak oxidation atmosphere roasting,step leaching of hydrochloric acid,solid-liquid separation,the monazite slag with sulfuric acid roasting water leaching,etc.In this paper,the roasting process of MPREC under a weak oxidation atmosphere was investigated.The study examines the thermal decomposition kinetics,phase transition process,and leaching behavior of MPREC in air/CO_(2)atmosphere.Results show that,the activation energy(Ea)for MPREC thermal decomposition in air and CO_(2)atmosphere are 146 and 320 kJ/mol,respectively.At temperature above 500℃in air or above 700℃in CO_(2)atmosphere,REOF are generated from bastnaesite through an in-situ reaction with CaO,which is decomposed from CaCO_(3),to form CaF_(2)and rare earth oxide(REO).Thus,F is regulated into solid phase.In an oxidizing atmosphere,the thermal decomposition of bastnaesite is accompanied by the rapid oxidation of Ce(Ⅲ).In co ntrast,the oxidation of Ce(Ⅲ)in a CO_(2)atmosphere is significantly inhibited.At 700℃,the oxidation rate of Ce in air is 74.09%,while in a CO_(2)atmosphere,it is only 33.83%.The hydrochloric acid leaching experiment shows that,the leaching rate of rare earth after roasting at 600℃under an air atmosphere reaches to 82.9%,and it reaches 87%after roasting at 800℃under a CO_(2)atmosphere.The reduction of Ce oxidation in a weak oxidizing atmosphere significantly improves the leaching rate of Ce.
基金the Major Research Plan of the National Natural Science Foundation of China(91962211)the Key Research and Development Program of Guangxi Province(Guike-AB22080056)+1 种基金the Beijing Nova Program(20230484379)the Major Program of Qingyuan Innovation Laboratory(00122004)。
文摘Ion-adsorption rare earth ore(IAREO)is a crucial source of mid-heavy rare earths elements(M-HRE).Reverse osmosis technology is a promising technique for the pre-concentration of the leach solution from in-situ leaching of IAREO.However,calcium sulfate scaling is inevitably formed in sulfate system,causing decreases in the flux and life time of membrane.Herein,to simulate the precipitation behavior of calcium sulfate in the leach solution of IAREO during reverse osmosis,a series of experiments was conducted in binary and quaternary supersaturated calcium sulfate solution systems.Experimental data show that the concentration of Ca^(2+)decreases with the increase of the concentration of Mg^(2+),and in-creases with the increase of the concentration of RE3+in both binary and quaternary systems.Whereas.the influence of Al^(3+)on the concentration of Ca^(2+)is different.This variation of the Ca^(2+)concentration is explained by thermodynamic analysis.The difference of association concentration for Mg^(2+),Al^(3+)and RE^(3+)with SO_(4)^(2-)in binary or quaternary system is the main reason.Finally,the influence and mechanisms of antiscalant on the precipitation behavior of calcium sulfate are discussed.X-ray diffraction(XRD),Zeta potential and scanning electron microscopy(SEM)analyses reveal that polyacrylic acid(PAA)effectively inhibits the crystal growth of calcium sulfate,and the precipitation time of calcium sulfate is prolonged,indicating that PPA is a potential inhibitor for calcium sulfate scaling during the process of reverse osmosis.
基金supported by National Natural Science Foundation of China(52204376)Open Project of Yunnan Precious Metals Laboratory Co.(YPML-2023050266)Youth Foundation of Hebei Province(E2022103007)。
文摘NO catalytic oxidation is the key performance of the diesel oxidation catalyst(DOC).We present a facile deposition method for the core-shell rare-earth manganese-zirconium composite oxide that shows the Mn mullite phase uniform loading on the surface of zirconium-based composite(YMO/CYZO),which demonstrates a superior NO oxidation catalytic performance in simulated diesel combustion conditions and better thermal stability than mullite phase YMn_(2)O_(5)oxide.The NO oxidation at 250℃over YMO/CYZO-a approaches 25.2%in contrast to 13.52%over YMn_(2)O_(5)-a.Then the catalytic performance of YMO/CYZO,YMO and commercial 1 wt%Pt/Al_(2)O_(3)in a NO+O_(2)atmosphere was compared.The maximum conversion rate of YMO/CYZO to NO oxidation is 89.6%at 274℃with a GHSV of 50000 h^(-1),and the performance is superior to that of YMO(82.8%at 293℃)and 1 wt%Pt/Al_(2)O_(3)(68.6%,335℃).The NO-temperature programmed desorption(NO-TPD)and diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)results reveal that YMO/CYZO has multiple NO adsorption sites and high storage capacity.Furthermore,density functional theory(DFT)calculation indicates that YMO/CYZO has lower oxygen vacancy formation energies(E_(v)=0.93 eV)and favorable NO adsorption energies(E_(ads)=2.1 eV).Moreover,in situ X-ray photoelectron spectroscopy(XPS)characterization shows that the core-shell structure of YMO/CYZO has the potential to transmit active oxygen species to help realize Mn3+to Mn4+during the reaction process to enhance the conversion of NO*molecules,while NO oxidation reactions follow the MvK mechanism.
基金supported by the State Key Laboratory of Materials Low-Carbon Recycling,Beijing University of Technologysponsored by the Beijing Nova Program(20240484638),China。
文摘Replacing the oxygen evolution reaction(OER)with the anodic formaldehyde oxidation reaction(FOR)is crucial for achieving low-voltage dual-electrode hydrogen evolution.However,existing FOR catalysts face challenges such as low activity,high transition state barriers,and unclear reaction mechanisms.In this study,a three-dimensional nano-composite Cu_(2)O/Cu/Mn_(2)O_(3)heterogeneous catalyst with enhanced hydrogen spillover effect was synthesized through hydrothermal and photosensitive oxidation treatment techniques.The catalyst consists of~20 nm Cu_(2)O/Cu and 30-70 nm Mn_(2)O_(3)nanoparticles.The hydrogen spillover effect enhanced Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst demonstrated outstanding FOR performance,with an anode potential of only 0.128 V at a current density of 100 mA cm^(-2),significantly lower than that of the Cu_(2)O/Cu-CC catalyst(0.25 V)and the OER potential(1.726 V).Moreover,the Faraday efficiency of the Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst reached~100%.The electrocatalyst’s FOR performance remains stable over 50 h without decay,and its hydrogen evolution reaction(HER)performance surpasses that of Cu and MnOxelectrocatalysts.Density functional theory(DFT)calculations suggested that the Cu_(2)O/Cu/Mn_(2)O_(3)catalyst significantly lowers the energy barriers for C-H bond breaking(0.48 eV)and H-H bond formation(-0.99 eV)by promoting the hydrogen spillover effect.This study provides theoretical support for designing efficient and stable low-energy dual-electrode hydrogen evolution catalysts and validates their potential through experiments.
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2902203)the Key Research and Development Program of Guangxi Province(No.Guike-AB22080056)+2 种基金Beijing Nova Program(No.20230484379)the Science and Technology Innovation Fund of GRINM(No.2022PD0102)the Central Government Guides Local Science and Technology Development Fund Project(No.246Z4005G)。
文摘To achieve selective leaching of ion adsorption rare earth,it is necessary to thoroughly reveal the differences in the adsorption mechanisms of aluminum and rare earth elements.In this study,we investigated the adsorption processes of Dy and Al on the surface of K–homoionic kaolinite using batch experiments and sequential chemical extractions.The results revealed that the adsorption of Dy and Al,as well as the desorption of K,followed the Langmuir model.The maximum ion-exchangeable capacity of Dy was higher(9.39 mmol.kg^(-1))than that of Al(6.30 mmol.kg^(-1)).The ion exchange stoichiometry ratios of Dy–K and Al–K derived from the Langmuir model were2.0 and 2.6.The analysis of X-ray absorption fine structure(XAFS)and density functional theory(DFT)revealed that Dy and Al were adsorbed onto kaolinite as outer-sphere hydrated complexes via hydrogen bonds.Dy was adsorbed as[Dy(H_(2)O)_(10)]^(3+),and Al was adsorbed as[Al(OH)_(2)(H_(2)O)_(4)]^(+).In particular,the adsorption of Al resulted in protonation of the hydroxyl groups on the surface of the kaolinite.Based on the above insights,the higher ion exchange stoichiometry ratios are attributed to closer adsorption distances(6.04 A for Dy and 3.69 A for Al)and lower adsorption energies(-223.72 kJ.mol^(-1)for Dy and-268.33 kJ.mol^(-1)for Al).The maximum ionexchangeable capacity is related to the change of the surface electrical properties of kaolinite.The zeta potential was increased to-7.3 mV as the protonation resulted from aluminum adsorption,while Dy adsorption had a minor effect,maintaining a value of-17.5 m V.
文摘This article briefly reviews the major research progress of 9 typical material fields,including rare earth luminescence materials,catalysis,rare earth materials for biomedical applications,magnetic materials,optical crystals,molecular-based materials,energy materials,metals and alloys,as well as rare earth extraction,separation and recycling in the year 2024.The aim of the review is to summarize the past and look into the future,and it will provide a basic overview of domestic work in related fields last year.Due to the abundance of content,the review strives to be concise.
基金Project supported by the National Natural Science Foundation of China(52274355)the National Key Research and Development Program of China(2022YFC2905305)+1 种基金the Gansu Province Science and Technology Major Special Project,China(22ZD6GD061)the Inner Mongolia Autonomous Region Science and Technology Revitalization of Inner Mongolia Cooperation Project,China(2022YFXM0001)。
文摘To solve the problem of ammonia wastewater pollution generated from preparing rare earth carbonate using the ammonium bicarbonate precipitation method,an eco-friendly precipitant,magnesium bicarbonate,was used to prepare lanthanum cerium carbonate.The lanthanum cerium sulfate solution obtained from the smelting and separation of Baotou mixed rare earth ore was used as the raw material.The influence of pH on the content of impurities,including SO^(2-)_(4)and magnesium,and the existing states of SO^(2-)_(4)n lanthanum cerium carbonate products,as well as the thermal decomposition behavior of the products,were deeply explored.SO^(2-)_(4)mainly exists in the form of rare earth sulfate complex salts in lanthanum cerium carbonate products.The fo rmation of the salts can be effectively avoided by adjusting the pH of the precipitation process.Then the content of SO^(2-)_(4)in the product is controlled.When the pH ranges from 6.00 to 7.12,the content of SO^(2-)_(4)in the product ranges from 0.42 wt%to 0.99 wt%.The content of MgO is lower than 0.04 wt%.Both contents meet the requirements of the national standard GB/T 16479-2020.In this study,lanthanum cerium carbonate products with low-content SO^(2-)_(4)were prepared.In addition,the existing states of SO^(2-)_(4)in the products are revealed.The research provides a new method for controlling the impurity content in preparing lanthanum cerium carbonate.
文摘This article briefly reviews the major research progress of 9 typical material fields,including rare earth luminescence materials,catalysis,rare earth materials for biomedical applications,magnetic materials,optical crystals,molecular-based materials,energy materials,metals and alloys,as well as rare earth extraction,separation and recycling in the year 2024.The aim of the review is to summarize the past and look into the future,and it will provide a basic overview of domestic work in related fields last year.Due to the abundance of content,the review strives to be concise.
基金Project supported by the National Key Research and Development Program(2021YFB3501101)Beijing Nova Program(20220484827)+2 种基金National Natural Science Foundation of China(52304370)Central Government Guidance Local Science and Technology Development Fund Project of Hebei Province(236Z4102G)Natural Science Foundation of Hebei Province(E2022103012)。
文摘Rare earth carbonates are essential precursors for the synthesis of oxide materials.In this study,we utilized in situ monitoring equipment to explore the alterations in the crystallization during the coprecipitation synthesis of cerium carbonate.By controlling the crystallization pathway and in the absence of any te mplating agents,we successfully synthesized a unique sphe rical self-assembled cerium oxide particle(Ceria-S).The Ceria-S exhibits excellent polishing performance.The crystallization process of cerium carbonate at 50℃persists for roughly 50 min.During the initial stages of crystallization from 0 to t_(3),the precipitated particles are amorphous.This is followed by a plateau phase of crystal growth from t_(3)to t_(5).Subsequently,during the burst crystallization phase from t_(5)to t_(6),Ce_(2)(CO_(3))_(3)·6H_(2)O and Ce_(2)O(CO_(3))_(2)·nH2O are formed,exhibiting a rod-like crystal morphology.By rapidly drying the precipitated particles at 60℃for 10 min and calcining,Ceria-S is obtained.The Ceria-S,with an average diameter of 180 nm,is assembled from primary cerium oxide nanoparticles of approximately 15 nm.Owing to the self-assembly structure of cerium oxide spherical nanoparticles,they exhibit a significantly larger specific surface area,resulting in an elevated concentration of Ce^(3+)as high as 35.5%.The Ceria-S exhibits a polishing removal rate of 420 nm/min,effectively decreasing the surface roughness(S_(a))of K9 glass from 1.605 to 0.404 nm.
