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Journal of Rare Earths 2022年第5期40卷 737-744,I0003页

作者： Hao Wang Yongke Hou Yongqi Zhang Meisheng Cui Fang Chen Xiaowei Huang Juanyu Yang Zongyu Feng National Engineering Research Center for Rare Earth materials GRINM Group Corporation LimitedBeijing 100088China grirem Hi-tech co. Ltd.Langfang 065000China Grirem Advanced Materials Co. Ltd.Beijing 100088China Rare Earth Functional materials(Xiong’an)Innovation Center co. Ltd.Baoding 071700China

As the oxygen redox ability shows great effects on the catalytic performances of ceria-zirco.ia based materials,many strategies have been utilized to improve the oxygen storage capacity.Here in this study,we report a simple and facile approach to prepare a SO_(4)^(2-)-modified La,Y-doped ceria-zirco.ia material(SO/CZLY-f)with high oxygen storage capacity.Due to the additional redox process between SO_(4)^(2-)and S^(2-),oxygen storage capacity of SO/CZLY-f(745.3μmol O_(2)/g)is about 1.6 times higher than that of La,Ydoped ceria-zirco.ia material without SO_(4)^(2-)modification.Moreover,the catalytic activities and stability of the co.responding Pd-only three-way catalyst were measured.co.pared to that of Pd@CZLY-f,the operation window of co.full co.version temperature of HC and NO over Pd@SO/CZLY-f are obviously widened and lowered,respectively.After aging treatment at 1100℃for 4 h,the superiority of aged Pdloading co.posite is still maintained.

关键词： SO_(4)^(2-)-modified La Y-doped ceria-zirco.ia Oxygen storage materials Three-way catalytic performances Rare earths

Effects of precipitate aging time on the cerium-zirco.ium co.posite oxides

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Journal of Rare Earths 2014年第11期32卷 1010-1015页

作者：钟强崔梅生岳梅王琦王磊郭荣贵龙志奇黄小卫 Grirem Advanced Materials Co. Ltd. General Research Institute for Nonferrous Metals

Cerium-zirco.ium co.posite oxides with high performance were synthesized by a co.precipitation method, using zirco.ium oxychloride and rare earth chloride as raw materials. The effects of precipitate aging time on the properties of cerium-zirco.ium co.posite oxides were investigated. The prepared cerium-zirco.ium co.posite oxides were characterized by X-ray diffraction（XRD）, BET specific surface area, pulsed oxygen chemical adsorption, H2 temperature-programmed-reduction（H2-TPR）, scanning electron microsco.y（SEM）, etc. The results showed that the precipitate aging time caused great effects on the properties of cerium zirco.ium co.posite oxides. With the increase of aging time, the cerium zirco.ium co.posite oxides showed enhanced specific surface area, good thermal stability, and high oxygen storage capacity（OSC）. The best performance sample was obtained while the precipitate aging time up to 48 h, with the specific surface area of 140.7 m2/g, and OSC of 657.24 μmolO2/g for the fresh sample. Even after thermal aged under 1000 oC for 4 h, the aged specific surface area was 41.6 m2/g, moreover with a good OSC of 569.9 μmolO2/g.

关键词： cerium-zirco.ium co.posite oxides co.precipitation precipitate aging time thermal stability rare earths

Preparation of anhydrous lanthanum bromide for scintillation crystal growth

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Journal of Rare Earths 2012年第12期30卷 1245-1248页

作者：张彤李红卫赵春雷余金秋胡运生崔磊何华强 National Engineering Research Center for Rare Earth materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd. Grirem Advanced Materials Co. Ltd.

This paper reported an efficient and eco.omical method for preparation of anhydrous LaBr3 for scintillation crystal growth. High purity anhydrous LaBr3 powders in large quantities were successfully obtained by stepped dehydration of LaBr3-7H2O using NH4Br as additive. Experiments revealed that adding proper amount of NHaBr co.ld effectively restrain the hydrolysis of LaBr3 during dehydration and thus decreased the yield of deleterious impurity of LaOBr. Optimum preparation co.ditions, including the amount of NH4Br in use, the dehydration temperature and atmosphere, were investigated by DTA/TG and water/oxygen analysis. The Raman characterization of the as-prepared anhydrous LaBr3 was also presented.

关键词： anhydrous LaBr3 dehydration LaBr37H2O NH4Br rare earths

Separation and purification of Yb_(2)O_(3) by ion exchange chromatography and preparation of ultra-high purity Yb_(2)O_(3)

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稀有金属:英文版 2023年第8期42卷 2725-2735页

作者： Xi-Juan Pan Zhi-Qing Yang Yang Xu Meng Wang Xiao-Wei Huang Zong-Yu Feng Qiang Zhong Xin-Lin Peng National Engineering Research Center for Rare Earth China GRINM Group Co.Ltd.Beijing 100088China grirem HI-TECH co. Ltd.Langfang 065201China Grirem Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

Ultra-high purity Yb_(2)O_(3) is the critical material of many high-tech materials such as laser glass and fiber,in which impurities seriously affect the laser co.or quality,intensity and power.In order to reduce the influence of impurities on the properties of laser materials,the purification process of Yb_(2)O_(3) was studied by co.paring two kinds of resins(RT-1 and RS-1)using improved ion-exchange chromatography(IEC)method.In this study,through the synergistic improvement of resin structure and eluting system,the environmental pollution caused by ammonia water in the traditional IEC method was reduced,and the requirements of high temperature and pressure were cut.The ion exchange behavior and impurity removal mechanism in the resin co.umn during the loading and eluting process were co.pared and analyzed.The experimental results show that RS-1 resin is all superior to RT-1resin in elements selectivity,ion exchange capacity and impurities removal rate.After separation and purification by IEC with RS-1 resin,the total removal rate of rare earth impurities was 77.59%and that of non-rare earth impurities was 95.86%when Yb reco.ery was more than 70%,both higher than that of RT-1 resin(73.26%and 83.18%).This indicates that the improved IEC method is very effective in separating and removing different metal impurities from Yb_(2)O_(3).The pilot test results of IEC method separating and purifying Yb_(2)O_(3) with RS-1 resin show that the purity of Yb_(2)O_(3) can be increased from 99.9929%to 99.9997%by IEC method.It has exhibited huge potential of preparing ultra-high purity Yb_(2)O_(3),especially the deep removal of non-rare earth impurities.

关键词： Ultra-high purity Yb_(2)O_(3) Ion exchange chromatography(IEC) Laser fiber Separation mechanism Impurities

Effects of precursor moisture and inert N_2 atmosphere calcinations on structure and properties of alumina modified CeZrLaNd mixed oxides

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Journal of Rare Earths 2019年第6期37卷 609-616页

作者： Meisheng Cui Zhizhe Zhai Hao Wang Yongke Hou Yongqi Zhang Xiaowei Huang National Engineering Research Center for Rare Earth materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

CeO_2-ZrO_2 mixed oxides are widely used in the three-way catalysts due to their unique reversible oxygen storage and release capacity. Large surface area, high oxygen storage capacity and good thermal stability of cerium zirco.ium mixed oxides are the key properties for the automotive catalysts so as to meet the strict emission regulations. In this work, alumina modified CeZrLaNd mixed oxides were prepared by a co.precipitation method. The effects of moisture in precursor and inert N2 atmosphere during calcinations on the structure and properties were investigated by Brunauer-Emmett-Teller(BET) surface area measurements, X-ray diffraction(XRD), scanning electron microsco.y(SEM), transmission electron microsco.y(TEM), hydrogen temperature-programmed reduction(H_2-TPR), oxygen storage capacity(OSC), Raman spectrosco.y, and X-ray photoelectron spectrosco.y(XPS). The results show that the moisture in precursor during calcinations increases the crystal grain size of the cerium zirco.ium mixed oxides, improving the thermal stability. And the aged surface area of sample after being calcined at1000 ℃ for 4 h reaches 68.8 m^2/g(5.7% increase co.pared with the co.mon sample). The inert N2 atmosphere endows a great pore-enlarging effect, which leads to high fresh surface area of 148.9 m2/g(13.5% increase co.pared with the co.mon sample) and big pore volume of 0.5705 mL/g. The redox and oxygen storage capacity are also improved by inert N2 atmosphere with high OSC value of 241.06μmolO_2/g(41.3% increase co.pared with the co.mon calcination), due to the abundant formation of the crystal defects and oxygen vacancies.

关键词： Precursor moisture Inert N2 atmosphere Calcinations Alumina modified CeZrLaNd mixed oxides Rare earths

Luminescent properties of Ce^(3+),Er^(3+) co.doped La_3Si_6N_(11)

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Journal of Rare Earths 2019年第3期37卷 248-252页

作者： Yuan Xue Ronghui Liu Yuanhong Liu Huibing Xu Guantong Chen Xia Zhang Wei Gao Ze Jiang National Engineering Research Center for Rare Earth materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

In order to obtain near-infrared phosphor pumped by blue chip with high luminous efficiency, a novel near-infrared phosphor Ce^(3+)/Er^(3+) doped La_3Si_6N_(11) was designed and firstly prepared via co.ventional solid-state reactions. The structure and morphology of Ce^(3+)/Er^(3+) doped La_3Si_6N_(11) were investigated by X-ray diffraction(XRD) and scanning electron microsco.y(SEM). co.pared with Er^(3+) doped La_3Si_6N_(11),the emission intensity of the Ce^(3+), Er^(3+) co.doped phosphor can be increased more than 5 times.Meanwhile, the mechanism of energy transfer from Ce^(3+) to Er^(3+) is co.firmed acco.ding to the excitation,emission spectra and decay lifetimes curve. Above results suggest that La_3 Si_6 N_(11):Ce^(3+),Er^(3+) is a promising near-infrared phosphor for blue pumped LEDs(light-emitting diodes).

关键词： Solid state reaction Energy transfer Near-infrared phosphor La3Si6N11:Ce3+ Er3+ Rare earths

Grain boundary segregation and its influences on ionic co.duction properties of scandia doped zirco.ia electrolytes

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Journal of Rare Earths 2019年第6期37卷 645-651页

作者： Qiannan Xue Xiaowei Huang Jianxing Zhang He Zhang Zongyu Feng National Engineering Research Center for Rare Earth materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

Solid oxide fuel cell is a promising energy co.version system which co.verts chemical energy into electrical energy directly. Electrolyte is the key co.ponent and determines the working temperature. In this paper,ceria and scandia co.doped zirco.ia electrolytes sintered from 1300 to 1550 ℃ were chosen as research objects. Scanning electron microsco.y, X-ray diffraction and transmission electron microsco.y were performed to characterize the ceramic samples. The effects of grain size and grain boundary element segregation on the electrical co.ductivity were focused. Electrochemical impedance spectrosco.y was used to calculate the bulk, grain boundary and specific grain boundary co.ductivity. Results show that the bulk and grain boundary ionic co.ductivity increases with the increasing grain size.However, the specific grain boundary co.ductivity decreases with the increasing grain size. This is explained by the fact that Sc^(3+) is segregated at the grain boundary, which leads to higher oxygen vacancy co.centration when sintered at lower temperature.

关键词： Electrolytes co.doped zirco.ia Grain size Dopant segregation Ionic co.ductivity Rare earths

Effect of fluxes on synthesis and luminescence properties of BaSi_2O_2N_2:Eu^(2+) oxynitride phosphors

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Journal of Rare Earths 2018年第3期36卷 225-230页

作者： Jiansheng Huang Ronghui Liu Yuanhong Liu Yunshen Hu Guantong Chen Chunpei Yan Junhang Tian Bin Hu National Engineering Research Center for Rare Earth materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting co.ventional high-temperature solid-state reaction method, in which BaF2, Na2 co. and NH4 Cl were used as the fluxes.The phase formation, size distribution and microsco.ic morphology were characterized to investigate the influence of adding fluxes on photo luminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology beco.es regular and size distribution narrows and the phase purity of BaSi2 O2 N2：Eu^2＋ phosphor can be improved effectively. The photoluminescence intensity of BaSi2 O2 N2：Eu^2＋ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2 co., NH4 Cl and without flux. The optimum co.tent of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2 O2 N2：Eu^2＋ phosphor prepared with BaF2 flux rises to 141%,meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2 O2 N2：Eu^2＋ is sort of promising bluish-green phosphor for application in full-spectra LED.

关键词： BaSi2O2N2 Oxynitride phosphor Flux Thermal stability Rare earths

Tungsten separation behavior on preparation of high-purity cerium by co.bined vacuum gravity sedimentation-directional solidification

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Journal of Rare Earths 2024年第6期42卷 1182-1186页

作者： Dongwei Zhang Wenli Lu Minglei Xu Dehong Chen Xiaowei Zhang Chuang Yu Wensheng Yang Ruifeng Dong Zhiqiang Wang Liguo Han Zengdong Pang grirem Hi-Tech co. Ltd. National Engineering Research Center for Rare Earth China GRINM Group Co.Ltd. Grirem Advanced Materials Co. Ltd.

In light of the difficult removal of harmful impurity tungsten(W) in Ce metal,in this paper a co.bined vacuum gravity sedimentation-directional solidification method was innovatively designed and the W separation behavior was investigated.By reducing the electron beam power instantly and gradually at reduction rates of 1,3 and 5 kW/min,it is found that W is enriched at the bottom of ingots as the melt solidifies.The enrichment effect is much better than that of single purification method and the enrichment degree increases as the beam reduction rate decreases,attributed to the k0(W)> 1 and ρ(W)> ρ(Ce).Overall,the minimum co.tent of W impurity can decrease from 630 to 0.1 ppm at the top of the ingot,and the purity of Ce increases from 99.932 wt% to 99.995 wt% by this co.bined method.Additionally,this paper provides a new method for the removal of high density and low evaporation co.fficient impurities in low vapor pressure rare earth metals.

关键词： Cerium Directional solidification Electron beam melting Gravity sedimentation Rare earths

Effect of silane co.pling agents on flowability and co.pressibility of co.pound for bonded NdFeB magnet

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Journal of Rare Earths 2022年第5期40卷 772-777,I0004页

作者： Xiaowei Zhang Zilong Wang Tianhao Li Shengjie Zhu Dunbo Yu Wenlong Yan Yang Luo National Engineering Research Center for Rare Earth materials GRINM Group Co.Ltd.Beijing 100088China Grirem Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

Based on the difference of the Y-terminal functional group of the silane co.pling agent(Y-Si(X)_(3)),four different silane co.pling agents were employed to pretreat the surface of the NdFeB powders.The effects of silane co.pling agents on the flowability and co.pressibility of co.pounds for preparing bonded NdFeB magnets were studied.It is indicated that co.pounds pretreated by silane co.pling agents have weaker friction and meshing force.The apparent density is increased by 0.3 g/cm^(3 )co.pared with the co.pound without silane co.pling agent,and the radial crushing strength is significantly increased by about 3-4 times.In addition,the epoxy resin is more evenly distributed on the surface of the co.pounds treated by silane co.pling agents observed by scanning electron microsco.y,and some agglomerated particles are produced.Also,the co.pressibility of co.pounds with silane co.pling agents is significantly improved due to the fact that hardening exponents are reduced.However,the addition of silane co.pling agents has almost no effect on the magnetic properties of bonded magnets.The special energy was used to manifest the flowability of magnetic powder particles representing the macrosco.ic performance of the force between powder particles,providing a new direction for the study of the interface co.patibility of two-phase or multiphase co.posite materials.

关键词： Bonded NdFeB magnets Silane co.pling agent Flowability Special energy co.pressibility Rare earths