Effect of rare earths on mechanical properties of plasma nitrocarburized surface layer of 17-4PH steel

The aim of this investigation is to reveal the influence of rare earths(RE) addition on mechanical properties of plasma nitrocarburized 17-4PH steel.The nitrocarburized layers were characterized by optical microscope,scanning electron microscope equipped with energy dispersive X-ray analyzer,X-ray diffractometer,microhardness tester and pin-on-disc tribometer.The results showed that RE atoms could diffuse into the surface layer of 17-4PH steel plasma nitrocarburized at 500 °C for 4 h and did not change the ...

New Rare-Earth Containing (Sr_(1-y)Eu_y)_2Al_2Si_(10)N_(14)O_4 Phosphors for Light-Emitting Diodes

Remarkable progress was made in the development of white-light-emitting diodes （LEDs）. White LEDs provided a light element having a semiconductor InGaN light-emitting chip （blue or UV LEDs） and luminescent phosphors. Here we reported the sialon s-phase of （Sr,Eu）2A12Si10N14O4. Eu^2＋ activator ions that were substituted for the strontium site represented a new type of yeUow-green phosphor that could be excited by blue LEDs used for application in the fabrication of white LEDs.

Influence of rare earth elements on corrosion resistance of BFe10-1-1 alloys in flowing marine water

The corrosion behavior of BFe10-1-1 alloy with different rare earth （RE） contents in simulated flowing marine water was investigated by X-ray diffractometer and scanning electron microscope （SEM）. It was demonstrated that the corrosion rate of BFel0-1-1 alloy with the same chemical compositions in faster flow velocity of marine water was higher than that in a lower flow velocity of marine water. Fixing the flow velocity, BFe 10-1-1 alloy had the best flushing corrosion resistance when the RE content was 0.04wt.%. The consequence of such good corrosion resistance was attributed to the formation of compact protective film on alloy surface containing RE phase such as CeNis. The RE-contained film combines with other corrosion products firmly, which was difficult to fall off from the alloy surface in the flowing marine water. Additionally, SEM analysis confirmed that pitting mechanism, which would be transformed to spalling mechanism gradually with further increasing RE content, was the prevalent mechanism when the alloy contained 0.04wt.%RE.

Syntheses, Characterization and Antitumour Activities of Rare Earth Metal Complexes with 2-(((4,6-dimethyl)-2-Pyrimidinyl)thio)-Acetic Acid

Eight rare earth metal （ Ⅲ ） complexes with 2- （ （（4,6-dimethyl）-2-pyrimidinyl） thio）-acetic acid, LnL3· n H2O [HL = 2-（（（4,6-dimethyl）-2-pyrimidinyl）thio）-acetic acid; Ln = La, Ce, Pr, Nd, Sm Eu, Gd, Tb; n = 4 or 5], were prepared and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR and ^1H- NMR. The results reveal that carboxyl group of the hgand coordinates with rare earth ions in bidentate mode after deprotonated. The water molecules exist as crystal water in the complexes. The anti-tumour activities of HL and some complexes were tested by both the MTT and SRB methods. The results show that the suppression ratios of some complexes against the tested tumour cells （HL-60 human leukemia cell lines, BGC-823 human gastric carcinoma cell lines, hela human cervix adenocarcinoma cell lines and Bel-7402 human hepatic carcinoma cell lines） are superior to HL.

Preparation of Nanocrystalline Rare Earth Mixed Oxides DyFe_x Co_(1- x)O_(3-δ) and Its Conductivity

Nanocrystalline rare earth mixed oxides DyFe x Co 1- x O 3- δ were prepared by sol gel method and characterized by X ray diffraction (XRD), thermogravimetric analysis (TG DTA) and scanning electron microscope (SEM). The results show that DyFe x Co 1- x O 3- δ has the structure of perovskite type at 800 ℃ for 2 h calcination. The conductivity of the materials at different temperature was measured by four probe instrumentation and two pole method. The results show that the conductivity of mixed oxides DyFe x Co 1- x O 3- δ is higher than those of un mixed oxides DyFeO 3 and DyCoO 3 and the conductivity is the best at x =0.8 in the matter of DyFe x Co 1- x O 3- δ . The conductivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800 ℃. However, the spinodals are different with different ration of Fe 3+ and Co 3+ . This kind of oxide is a conductive pottery material.

New Advances in Structural Studies of Barium Rare-Earth Fluor-Carbonate Minerals

This paper summarizes the new developments in the study of barium rare-earth fluor-carbonate mineral structures .The second order superstructure of cebaite -(Ce ) was solved by using high power X-ray single crystal diffractometer . Five kinds of coordination forms were found . All atoms in the cell , including C and F , were properly located . In the process of study in a cordylite-(Ce ), a new mineral was discovered , whose chemical formula is (Ca0.5□0.5) BaCe2 (CO3)4F . It is isostructural with baiyuneboite - (Ce ), but different in composition (Na in baiyuneboite- (Ce ) is substituted by Ca disorderly ) . On the basis of the studies a proposal to re-define cordylite-(Ce )as a mineral group name is put forth by the authors . Finally a new type of twinning of huanghoite-(Ce ) was found on the systematical absence of diffraction data by means of a single crystal diffractometer .

Study on Rare Earth Electrolyte of Ce_(0.9)RE_(0.1)O_(2-δ) (RE=Pr, Nd, Sm, Gd, Dy)

The solid solutions Ce_(0.9)RE_(0.1)O_(2-δ)(RE=Pr, Nd,Sm, Gd, Dy) were prepared by sol-gel method. The XRD measurement shows that the solid solution is crystallized in cubic fluorite-type structure and the cell volume of Ce_(0.9)RE_(0.1)O_(2-δ) decreases with the increase of atomic number of RE. The ionic conduction for Ce_(0.9)RE_(0.1)O_(2-δ) was measured by impedance spectroscopy and Ce_(0.9)Pr_(0.1)O_(2-δ) has better conductivity. The linear thermal expansion of Ce_(0.9)RE_(0.1)O_(2-δ) decreases with the increase of atomic number of RE.

Application of Rare Earth Spin Finishes Chloride on PET/PA Composite Super-fine Denier Fiber

The primariy application of rare - earth spin finishes on PET/PA composite super - fine denier fiber has been studied in this paper. It results in the improvement of fi-ber’s properties, such as increased whiteness, brightness and brilliance, effective and uniform spliting of compos-ite fiber into super - fine denier fiber and enhanced dye-ing effect.

基于P-TRM的中国稀土产业技术创新的政策演化路径研究

稀土被称为“工业维生素”,已成为全球各国资源争夺和技术竞争的焦点。我国是稀土资源大国,政府高度重视稀土产业技术的创新,出台了系列创新政策以推动中国从稀土大国向稀土强国转变。收集1978—2021年国家层面颁布的63份与稀土产业相关的创新政策文本,结合内容分析法,构建政策-技术路线图(P-TRM)分析框架,剖析稀土产业技术创新的政策演化历程与路径。研究发现:从创新政策工具来看,稀土产业创新政策工具呈现出进入阶段以结构型创新政策工具为主,到逐步追赶阶段结构型与功能型创新政策工具同时发力,再到跨越阶段由功能型创新政策工具占据主导的演进趋势;从政策作用技术环节来看,从进入阶段主要发力于原材料制备技术,到逐步追赶阶段聚焦关键部件加工和终端产品制造技术,最后跨越阶段延伸到废弃产品循环利用技术,呈现出从关注单一技术环节到全技术链的演进趋势;从政策演化路径来看,稀土产业创新政策随着稀土产业创新生态的演变而变化,不断完善稀土产业创新生态系统,促进稀土全产业链技术的创新。最后,针对中国稀土产业技术创新政策的优化提出政策建议。

Rare Earths and Magnetic Refrigeration

Magnetic refrigeration is a revolutionary, efficient, environmentally friendly cooling technology, which is on the threshold of commercialization. The magnetic rare earth materials are utilized as the magnetic refrigerants in most cooling devices, and for many cooling application the Nd2Fe14B permanent magnets are employed as the source of the magnetic field. The status of the near room temperature magnetic cooling was reviewed.

Bioleaching of trace elements and rare earth elements from coal fly ash

Coal fly ash originated from coal combustion has high concentrations of metals. If suitable leaching techniques are identified, then coal fly ash could serve as a useful source of valuable minerals including rare earth elements (REEs). In this study, three microbial strains, Candida bombicola, Phanerochaete chrysosporium and Cryptococcus curvatus were tested on their performance of leaching trace elements and REEs from fly ash. Through comparing mineral loss and leaching efficiencies resulting from indirect leaching or use of the culture supernatant, C. bombicola was identified to be the best leading to the highest mineral loss and extracting efficiencies of trace elements and REEs among the three strains. The highest mineral loss observed from using the supernatant of this yeast strain was 59.7%. Among all trace elements, As and Mo had the highest leaching efficiency of 80.9% and 79.5%. respectively. The same leaching test led to 67.7% of Yb and 64.6% of Er dissolved from the ash. This study, thus, demonstrated that bioleaching is feasible for leaching metals out of fly ash. The C. bombicola strain deserves further investigation due to its robust actions on metal leaching.

XPS Studies on Rare Earth Oxide LSCO/YSZ Electrodes

The X ray diffraction spectra and X ray photoelectron spectroscopy were measured for Sr doped La 1- x Sr x CoO 3 materials with perovskite structure prepared by the solid state reaction method. The influence of heat treatment temperature on the average crystal size of La 1- x Sr x CoO 3 was studied. The surface chemical states of La 1- x Sr x CoO 3 cathodes with different Sr doped content were discussed. The experimental results show that average crystal size of La 1- x Sr x CoO 3 under the condition of heat treatment in the range of 900～1200 ℃ is larger than that at other temperatures, which is of benefit to forming porous electrodes. When La is replaced by Sr gradually, the oxygen vacancy concentration increases. It is of benefit to enhancing the transport property of oxygen ion.

Cluster Based Strategy to Improve Competitiveness of Rare Earth Industry in China——Taking Emerging Rare Earth Industry Cluster in Baotou As An Example

China′s rare earth industry has shown its strong competence, but notably this competence is mostly based on the comparative advantages in natural resources and production costs that will not provide a long-term momentum for the growth of the industrial competitiveness. It has become an urgent task now for China′s rare earth industry to improve its competitiveness through adjusting the product structure and enhancing the technological application, to gain much healthier and more sustainable growth in the future. This paper aims to present a new development strategy based on the industry cluster theory to improve the competitiveness of China′s rare earth industry with a case study on the emerging rare earth industry cluster in Baotou. The paper first reviews the cluster theory and explains why it matters to industrial competitiveness briefly, and then proposes a general framework for implementing cluster policies and strategies in practice. Following that, a case to study the emerging rare earth industry cluster in Baotou was presented and a cluster initiative based on the general framework was developed. The objectives of the cluster initiative and the role of government on initiative organizing and cluster upgrading were discussed in detail. In the end, general implications drawn from the case of Baotou were summarized, which try to provide some insights for applying cluster-based strategies to the rare earth industry of China.

Inorganic Speciation of Rare Earth Elements in Chaohu Lake and Longganhu Lake, East China

Inorganic speciation of dissolved rare earth elements （REEs） were calculated for Chaohu Lake and Longganhu Lake by using the program MINTEQ 2.30. The result shows that REE-Carbonate complexes, which account for more than 93% of total REE are the dominate and typically species in solution. Moreover, carbonator complexes （LnCO3^＋ ） were predicted to be the dominant species when pH between 7.2 and 8.0 and bicarbonate complexes （Ln （CO3）2^-） were predicted to be the dominant species when pH 〉 8.0. The free ion specie （i .e., Ln^3＋ ） increases in these waters with pH decreasing and accounts for about 5.03 %. The percentage of REE-phosphate complexes account for 1.61% of the dissolved REEs. REE-phosphate for light REEs complexes are supersaturated in Chaohu Lake and Longganhu Lake. Furthermore, LnPO4 for heavy REEs are supersaturated in west of Chaohu Lake in high water period. PO4^3- is responsible for limiting the dissolved REEs concentrations. REE-sulfate, REE-chloride, REE-fluoride and REE-hydroxide complexes, are negligible and generally account for less than 1% of the total dissolved REEs.

The World Production and Trade of Rare Earth Elements： The Position of the Pacific Area

In this paper we analyze the characteristics of the so-called rare earth elements （REEs） and its industrial applications. We present the policy, or lack thereof, in the countries in the Pacific Rim for its mining and commerce, and the current and future weight that rare earth minerals will have in international trade. The technological revolution experienced over the last 25 years, has brought the REEs to the public＇s attention for being instrumental in obtaining catalysts, lasers and optical fiber, luminescent substances and LEDs, superconductors, permanent magnets, batteries and ultra-capacitors. China＇s leading position as the supplier of these minerals worldwide, and its recent export restriction policy for domestic industrial activities have driven up international prices. Price increase for REEs is leading to the need for both recycling and its replacement. It has also led other countries in the Asia Pacific Rim to prospect new potential sites on their own territories, or even to restart operations in deposits that had been previously abandoned. Those strategies will likely gain greater importance as environmental pollution problems associated with the exploitation, processing, and recovery of REEs increase.

Preparation and Properties of Eu^(3+) Rare Earth Complex and Fluorescent Fiber

A novel Eu^3＋ rare earth complex, composed of 4 - hydroxybenzolate acid and 1, 10 - phenanthroline ligands was synthesized. The apparent morphology, composition, thermal stability and fluorescent property of the rare earth complex were measured by TEM, Element analysis, IR, TG and Fluorescence spectrometer. The results indicated that this rare earth complex has sphere-like morphology and its diameter was about 100 nm. The complex has good thermal stability due to the strong coordination between the Eu^3＋ ions and the ligands. Based on the composition analysis, the complex structure formula was： Eu （HOC6 H4 COI）3 （phen） ·H2O Fluorescence spectra showed that the rare earth complex emission peaks were corresponding to the transition of ^5D0→7FJ（J=0,1,2,4）,. and the highest intensity fluorescence peak was at 617 nm. The luminescent fiber was prepared by blending melt-spinning with rare earth complex and polypropylene resin. It also has a good luminescent quality, which the strongest emission peak was at 619 nm. It could be considered suitable for industrial application.

Fractionation characteristics of rare earth elements(REEs) linked with secondary Fe, Mn, and Al minerals in soils

Soil secondary minerals are important scavengers of rare earth elements(REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs(La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs(LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs(HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of HREEs.The substantial fractions of REEs in soils extracted byoxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile(10 %–30 %), which were similar to the mass fraction of Fe(10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation.

Consolidation of rare earth enterprises to be finished in four years

'Rare Earth Industry Development Plan (2016-2020)' was formally introduced recently. According to the plan, by the end of 2020, the six rare earth groups will complete restructure of enterprises engaged in rare earth mining, smelting & separation and resources comprehensive utilization throughout the country. In the next step, the six groups, including CHINACLO, China Northern Rare Earth, Xiamen Tungsten, China Minmetals, Guangdong Rare Earth and China Southern Rare Earth Group, will continue to target at advancing rare earth industry consolidation with deliberate work plan and time schedule;