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Synthesis and photoluminescence properties of octahedral K_2(Ge,Si)F_6:Mn^(4+) red phosphor for white LED

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Journal of Rare Earths 2016年第12期34卷 1173-1178页

作者：金玉明刘荣辉陈观通刘元红马小乐邵冷冷王磊 National Engineering research Center for Rare Earth Materials General Research Institute for Nonferrous Metalsand Grirem Advanced Materials Co.Ltd.

A novel red-emitting K2（Ge,Si）F6：Mn^4＋ phosphor with uniform morphology was synthesized by co-precipitation method. The pure K2GeF6 phase with P63 mc space group other than P3m1 space group was affirmed just by incorporation of Si in K2GeF6 at room temperature according to XRD characterization. SEM images showed lamellar and octahedron grain morphology for K2GeF6：Mn^4＋ and K2（Ge,Si）F6：Mn^4＋ phosphors, respectively. It was also found that the photoluminescence excitation（PLE） and photoluminescence（PL） showed slight displacement in K2GeF6：Mn^4＋ and K2（Ge,Si）F6：Mn^4＋ system. And the zero-phonon line（ZPL） of the PL spectrum of K2GeF6：Mn^4＋ with Si showed a strong peak. Meanwhile crystalline field surrounding Mn^4＋ changes could affect the decay time in this fluoride system. The color gamut of the LED devices based on K2（Ge,Si）F6：Mn^4＋ and K2GeF6：Mn^4＋ reached up to 94.58% NTSC（National Television Standards Committee） and 94.386% NTSC, respectively, that was much higher than that based on nitride red phosphors. All these original characteristics in K2（Ge,Si）F6：Mn^4＋ phosphor are desirable for potential applications as a red phosphor for improving lighting and display quality of conventional white LEDs.

关键词： K2(Ge Si)F6:Mn4+ fluoride PLE and PL decay time phosphors rare earths

Effect of impurity ions on preparation of novel saponifier for rare earth extraction

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Journal of Rare Earths 2013年第9期31卷 905-910页

作者：肖燕飞冯宗玉黄小卫黄莉徐旸侯永可王猛 National Engineering research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsGrirem Advanced Materials Co.Ltd.

Magnesium bicarbonate, prepared by the carbonation of magnesium hydroxide slurry, was used as a novel saponifier to eliminate the ammonia nitrogen pollution in the rare earth extraction separation process. The effect of impurity ions introduced by system on the carbonation reaction of magnesium hydroxide was studied in the work. The results showed that the presence of Ca2＋could lead to side reactions so as to reduce the conversion rate of magnesium hydroxide, and a small number of rare earth ions would have great influence on the carbonation reaction. What’s more, there was no influence on carbonation reaction with the low concen-tration of Na＋or Mg2＋, the conversion rate of magnesium hydroxide could reach above 96%. This paper showed a practical theory which could provide scientific guidance for the preparation of novel saponifier in rare earth extraction separation process.

关键词： rare earths magnesium bicarbonate saponifier carbonation impurity ions

Technology development for rare earth cleaner hydrometallurgy in China

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Rare Metals 2015年第4期34卷 215-222页

作者： Xiao-Wei Huang Zhi-Qi Long Liang-Shi Wang Zong-Yu Feng National Engineering research Center for Rare Earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

China is the global leader in rare earth （RE） production using hydrometallurgical processes. Advantageous extraction techniques of rare earths from Baotou mixed rare earth minerals, bastnaesite, and ion-adsorption clays of rare earth deposits have been developed in China. The separation and purification technologies have also achieved rapid development. The industrial application processes for rare earth hydrometallurgy were summarized in the present paper. With the large demands and rapid development of rare earths, the issues of resources and environment are more prominent. This review gives an overview of the main processes that were developed in the past toward greener hydrometallurgy of rare earths in China. Based on the development of the rare earth industry, comprehensive utilization and cleaner production should still be focused on in the future, to support the sustainable development.

关键词： Rare earths Cleaner production Separation and purification Hydrometallurgy

Ammonium-iodide route to anhydrous EuI_2: mechanism and preparation

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Journal of Rare Earths 2015年第11期33卷 1189-1195页

作者：刁成鹏余金秋李红卫彭鹏吴浩何华强颜世宏胡运生 National Engineering research Center for Rare Earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

Anhydrous EuI2 is an essential raw material for novel Eu^2＋-doped halide scintillators such as SrI2：Eu, CsBa2I5：Eu and BaBrI ：Eu. An efficient and economic method to produce high purity anhydrous EuI2 is critical for future development and applications of these scintillators. In this paper, the ammonium-iodide route to anhydrous EuI2 was investigated, and anhydrous EuI2 with purity of 99.95 wt.% was successfully prepared. The dehydration mechanisms of europium iodide hydrate and its mixture with NH4I were comparatively investigated by X-ray diffraction（XRD）, thermal analysis and fluorescence spectroscopy. The thermal decomposition process of individual europium iodide hydrate was revealed as follows： EuI3·9H2O→EuI 3·8H2O→EuI 3·7H2O→EuI 2·H2O→EuI2, and the hydrolysis mechanism of europium hydrate was comprehensively studied. When europium iodide hydrate was dehydrated with NH4I, NH4Eu2I5 formed as an intermediate product, and the hydrolysis of EuI2 was effectively restrained. The role of NH4I as an iodination agent was also discussed.

关键词： anhydrous EuI2 ammonium iodide route scintillator rare earths

Preparation of scandia stabilized zirconia powder using microwave-hydrothermal method

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Journal of Rare Earths 2015年第7期33卷 746-751页

作者：敖红敏刘向生张赫周静黄小卫冯宗玉徐宏 Grirem Advanced Materials Co. Ltd. National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous Metals

Scandia stabilized zirconia powder （ScSZ） was first synthesized by a microwave-hydrothermal method. The crystalline and aggregated particle sizes were investigated by means of X-ray diffraction （XRD）, Raman, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Weakly agglomerated and well crystallized ScSZ powder was prepared by microwave-heating to 150 ℃ and 2.5 h. The structure of the ScSZ powder changed from a tetragonal to a cubic phase, and accordingly, the powder conductivity was increased from 90.55 to 120.56 ms/cm by the introduction of the mineralizer solutions （KOH＋K2CO3） during the microwave-hydrothermal processing.

关键词： scandia stabilized zirconia preparation microwave-hydrothermal mineralizer rare earths

Characterization of CeO_2-ZrO_2 mixed oxides prepared by two different co-precipitation methods

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Journal of Rare Earths 2013年第3期31卷 251-256页

作者：岳梅崔梅生张娜龙志奇黄小卫 National Engineering research Center for Rare Earth Materials General Research Institute for Nonferrous Metalsand Grirem Advanced Materials Co. Ltd.

A series of cerium zirconium mixed oxides were prepared by two co-precipitation methods using magnesium hydrogen carbonate （MHC） and mixed ammonia-ammonia hydrogen carbonate （AAHC） as precipitant respectively. The crystal structure, BET surface area and morphology of the produced cerium zirconium mixed oxides were characterized by X-ray diffraction （XRD）, Bru- mauer-Emmett-Teller （BET） and scanning electron microscopy （SEM） techniques. The reduction-oxidation behavior and oxygen storage capacity （OSC） performance were also studied by temperature programmed reduction （TPR） and oxygen pulse chemical adsorption methods. The XRD results demonstrated that the cerium zirconium mixed oxides obtained by both methods possessed struc ture of cubic solid solution phase. The fresh surface area calcinated at 600 ℃, aged surface area after 1000 ℃and OSC at 500 ℃ of cerium zirconium mixed oxides were determined to be 89.337, 34.784 ma/g, and 567 pmol O2/g for MHC method and 122.010, 46.307 m2/g, and 665 pmol O2/g for AAHC method, respectively.

关键词： cerium zirconium mixed oxide magnesium hydrogen carbonate mixed ammonia-ammonia hydrogen carbonate co-pre-cipitation rare earths

Recent Progress on Thermal Energy Storage for Coal-Fired Power Plant

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Journal of Thermal Science 2024年第6期33卷 2138-2150页

作者： WANG Wei ZHANG Jianyuan GU Yi LUO Qing ZHOU Guiqing LI Ang LU Guozhong MA Tingshan ZHAO Yuanzhu CHANG Yiming XUE Zhaonan Xi'an thermal power research institute CO. LTD.Xi'an 710054China State grid Liaoning electric power supply CO. LTD.Shenyang 110004China GD power Dalian Zhuanghe power generation CO. LTD.Zhuanghe 116431China

With countries proposing the goal of carbon neutrality,the clean transformation of energy structure has become a hot and trendy issue *** energy generation will account for the main proportion,but it also leads to the problem of unstable electricity *** present,large-scale energy storage technology is not yet *** the flexibility of coal-fired power plants to suppress the instability of renewable energy generation is a feasible *** energy storage is a feasible technology to improve the flexibility of coal-fired power *** article provides a review of the research on the flexibility transformation of coal-fired power plants based on heat storage technology,mainly including medium to low-temperature heat storage based on hot water tanks and high-temperature heat storage based on molten *** current technical difficulties are summarized,and future development prospects are *** combination of the thermal energy storage system and coal-fired power generation system is the foundation,and the control of the inclined temperature layer and the selection and development of molten salt are key *** authors hope that the research in this article can provide a reference for the flexibility transformation research of coal-fired power plants,and promote the application of heat storage foundation in specific coal-fired power plant transformation projects.

关键词： thermal energy storage coal-fired power station flexible regulation water tank heat storage mol saltheatstorage

The structure–activity relationships of Rh/CeO_(2)-ZrO_(2) catalysts based on Rh metal size effect in the three-way catalytic reactions

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Nano research 2024年第8期17卷 6870-6878页

作者： Dongming Chen Weixin Zhao Zihao Xu Zheng Zhao Juanyu Yang Yongke Hou Yongqi Zhang Zongyu Feng Meisheng Cui Xiaowei Huang National Engineering research Center for Rare Earth Grirem Advanced Materials Co.Ltd.Beijing 100088China Grirem Hi-Tech Co. Ltd.Sanhe 065201China General research Institute for Nonferrous Metals Beijing 100088China

With the continuous tightening of automotive emission regulations and the increasing promotion of energy-efficient hybrid vehicles,new challenges have arisen for the low-temperature performance of three-way catalysts(TWCs).To guide the design of next-generation TWCs,it is essential to further develop our understanding of the relationships between microstructure and catalytic ***,Rh/CeO_(2)–ZrO_(2) catalysts were synthesized with different Rh metal dispersion by using a combination of the wet impregnation method and reduction *** catalysts included Rh single-atom catalysts,cluster catalysts,and nanoparticle *** results showed that the Rh nanoparticle catalyst,with an average size of 1.9 nm,exhibited superior three-way catalytic performance compared to the other *** on the catalytic activity in a series of simple reaction atmospheres such as CO+O_(2),NO+CO,and hydrocarbons(HCs)+O_(2) and operando infrared spectroscopy,we found that metallic Rh sites on Rh nanoparticles are the key factor responsible for the low-temperature catalytic performance.

关键词： Rh/CeO_(2)-ZrO_(2) catalyst Rh metal size effect Rh nanoparticles three-way catalytic performance

Blue-emitting Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) phosphors for high CRI white LEDs

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Journal of Rare Earths 2021年第6期39卷 627-633,I0001页

作者： Yipeng Zhou Yunsheng Hu Ronghui Liu Yuanhong Liu Weidong Zhuang Min Cao Tongyu Gao Junhang Tian Yanfeng Li Guantong Chen National Engineering research Center for Rare Earth Materials GRINM Group Co.Ltd.Beijing100088China CRIREM Advanced Materials Co. Ltd.Beijing 100088China General research Institute for Nonferrous Metals Beijing 100088China

A broadband blue-emitting Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+)(x=0-0.2) phospho rs were synthesized,which can be used for near-UV pumped white light-emitting diodes(w-LEDs).The crystal structures,photoluminescence pro perties,external quantum efficiency,the rmal stability and application perfo rmance of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+),by partially substituting Sr^(2+) with Ca^(2+)(x=0-0.2),were studied by various analytical *** the Ca/Sr ratio of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) gradually increases,the emission peak of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) red-shiftes from 459 to 465 nm,corrected external quantum efficiency increases from 31.8% to 42.9%,and the thermal stability is also *** mechanism of the changes of the photoluminescence emission and excitation spectra,external quantum efficiency and thermal stability properties was also investigated in *** addition,a w-LED was fabricated by using SrLu_(2)O_(4):Ce^(3+)(blue),β-sialon:Eu^(2+)(green) and(Sr,Ca)AlSiN_(3):Eu^(2+)(red) phosphors combined with a 405 nm near-UV LED chip,and its color rendering index(CRI) reaches *** Sr_(0.8)Ca_(0.2)Lu_(2)O_(4):Ce^(3+) is applied as blue phosphor to substitute SrLu_(2)O_(4):Ce^(3+),the obtained w-LED devices have high luminous efficiency,and CRI greater than *** re sults show that the Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) can be potential blue phosphors for n-UV pumped high CRI w-LEDs application.

关键词： n-UV pumped w-LED Blue phosphor Red shift Excellent thermal stability High color rendering index Rare earths