Improvement strategy on thermophysical properties of A_(2)B_(2)O_(7)-type rare earth zirconates for thermal barrier coatings applications:A review

The A_(2)B_(2)O_(7)-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating(TBC) materials because of their low sintering rate,improved phase stability,and reduced thermal conductivity in contrast with the currently used yttria-partially stabilized zirconia (YSZ) in high operating temperature environments.This review summarizes the recent progress on rare earth zirconates for TBCs that insulate high-temperature gas from hot-section components in gas turbines.Based on the first principles,molecular dynamics,and new data-driven calculation approaches,doping and high-entropy strategies have now been adopted in advanced TBC materials design.In this paper,the solid-state heat transfer mechanism of TBCs is explained from two aspects,including heat conduction over the full operating temperature range and thermal radiation at medium and high temperature.This paper also provides new insights into design considerations of adaptive TBC materials,and the challenges and potential breakthroughs are further highlighted for extreme environmental applications.Strategies for improving thermophysical performance are proposed in two approaches:defect engineering and material compositing.

RESEARCH ON THE APPLICATION OF RARE EARTHS IN IRON AND STEEL IN RECENT YEARS

China has the biggest rare earths resource in the world,no wonder she pays much at-tention to the application of rare earth metals (REM).The application of REM in iron andsteel in China began at the end of 1950’s.The production of REM-treated iron and steelhad been made steady progress in the period of 1980’s.The production of REM-treatediron and steel in 1989 was 1.4 million tons and 250,000 tons respectively.The interest oftreating steel with REM in China keeps growing even in these years,It comes from the nat-

Rare Earth Application in Sealing Anodized Al-Based Metal Matrix Composites

A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.

Status of Applications of Rare Earth Metals to Precision Alloys

Rare earth resources in China are the most abundant, the production capability ranks second in the world. The first generation of rare earth-transition group permanent magnet alloy RECo5 developed in 1970's started using rare earths as substantial components. Because of the need of product diversity and to utilize rich resources of mixed rare earth metals, researchers are working on substitution of expensive elemental rare earth metals with cheaper cerium or mixed rare earths (rich in cerium, lanthanum or neodymium) to make lower cost permanent - magnet such as CeCo5. Ce[CoCuFe]5. etc.

The 5^(th) International Conference on Rare Earth Development and Applications ICRE′ 2007

The Second Circular Baotou/China August 7～11, 2007 Organized by The Chinese Society of Rare Earths (CSRE) Baotou National Rare-Earth Hi-Tech Industrial Development Zone Honorary Chairman: Xu Kuangdi, President, the Chinese Academy of Engineering Chairman: Gan Yong, President, General Institute of Iron & Steel; Chairman of CSRE Vice Chairmen: Zhou Chuandian, Xu Guangxian, Li Dongying, Lin Donglu, Tu Hailing, Yang Jianlin, Li Bingrong International Scientific Advisory Board: Gi-Ya Adachi(Japan), J.C.G. Bünzli(Switzerland), Patrick Burk (USA), Przemyslaw Deren(Poland),Philippe Goldner(France), K. A. Gschneider(USA), Huang Boyun(China), Dariusz Kaczorowski (Poland), Nogami Masayuki(Japan), Ni Jiazuan(China), Wieslaw Strek(Poland),Su Qiang(China), Alessandro Trovarelli(Italy), Wang Zhenxi(China), Yang Yingchang (China), Zhang Guocheng (China)

THE 6TH INTERNATIONAL CONFERENCE ON RARE EARTH DEVELOPMENT AND APPLICATIONS ICRE'2010(The Second Circular)

Beijing / China August 2-6, 2010 Organized by The Chinese Society of Rare Earths (CSRE) Co-Organized by Peking University (PKU), Roskill Information Services Ltd., Metallurgical Council

The 2nd International Conference on Rare Earth Development and Applications Held in Beijing

The 2nd International Conference on Rare Earth Development and Applications(ICRE’91),which wassponsored by the Chinese Society of Rare Earths,was held at Beijing International Convention Centre fromMay 27 through May 31,1991.290 scientists attended this conference,among them there were 63 foreign sci-entists.Prof.Yu Zongsen,vice-chairman of the Chinese Society of Rare Earths,presided over the openingceremony.Mr.Xu Daquan,deputy director of the Rare Earth Leading Group of the State Council,vice-minister

GUO BOSHENG,PIONEER FOR DEVELOPING RARE EARTH APPLICATION IN AGRICULTURE IN CHINA

Guo Bosheng, senior engineer/professor, is now a member of the Expert Group of the State Council Rare Earth Leading Group, PRC., director of Rare Earth Development Center for Agricultural Technique. He graduated from Moscow Fine Chemical Industry University in the Sovi-

The 2nd Chinese-Soviet Conference on Chemistry and Application of Rare Earths Held in Changchun and Shanghai

The 2nd Chinese-Soviet Conference on Chemistry and Application Rare Earths was held at ChangchunInstitute of Applied Chemistry, Academia Sinica, and Shanghai Institute of Metallurgy, Academia Sinica,China, on October 5～11, 1991. 10 representatives from USSR attended the conference. There were 47Chinese representatives in Changchun Conference and 77 in Shanghai Conference respectively, Prof. Nijiazan, Chinese chief representative, gave a lecture entitled“Progress and Research on Rare Earth Chemistryin China”, and Prof. I.A. Smirnov gave another lecture entitled“Physico-Chemical Investigation and Per-spective of Practical Application of CeO-PrO”.

Rare earth ion modified TiO_2 sols for photocatalysis application under visible light excitation

TiO_2 sols modified by rare earth (RE) ions (Ce^(4+), Eu^(3+), or Nd^(3+))were prepared by coprecipitation-peptization method. The photocatalysis activity was studied byinvestigating the photodegradation effects of active brilliant red dye X-3B. It is found that TiO_2sols modified by Ce^(4+), Eu^(3+), or Nd^(3+) have the anatase crystalline structure, which areprepared at 70℃. All RE^(n+)-TiO_2 sol samples have uniform nanoparticles with similar morphology,which are homogenously distributed in aqueous colloidal systems. The particle sizes are 10, 8, and12 nm for Nd^(3+)-TiO_2, Eu^(3+)-TiO_2, and Ce^(4+)-TiO_2, respectively. The character of ultrafineand positive charge sol particles contributes to the good adsorption of X-3B dye molecule on thesurface of titania (about 30% X-3B adsorption amount). Experimental results exhibit thatRE^(n+)-TiO_2 sol photocatalysts have the capability to photodegrade X-3B under visible lightirradiation. Nd^(3+)-TiO_2 and Eu^(3+)-TiO_2 show higher photocatalytic activity than Ce^(4+)-TiO_2,which is due to the difference of standard redox potential of RE^(n+)/RE^((n-1)+). RE^(n+)-TiO_2sols demonstrate more excellent interfacial adsorption and photodegradation effects to X-3B thanP_(25) TiO_2 crystallites. Moreover, the degradation mechanism of X-3B is proposed as dyephotosensitization and electron scavenging by rare earth ions.

Advances on Rare Earth Application in Pollution Ecology

The use of rare earth for inducing plant resistance was reviewed. The important developments in recent years were described, and rare earth can alleviate the pollution of acid rain, ozone, pesticide, heavy metals etc. in environment. The authors suggest that the mechanism of rare earth to inducing plant resistance and reducing plant injury is to control biochemical metabolism web in plant cell, to adjust its protection system of free radical, to maintain its photosynthesis, to protect cell membrane system and to carry through its function on mineral metabolism. Meanwhile some problems in the field were discussed as well.

Adsorption of Ce(Ⅳ) Anionic Nitrato Complexes onto Anion Exchangers and Its Application for Ce(Ⅳ) Separation from Rare Earths(Ⅲ)

Ce （Ⅳ） nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine （PVP） and quatemized PVP incorporated into porous silica matrix. The effect of nitric acid concentration （0.5～6 mol·L^-1） and temperature （278 ～318 K） on Ce（ Ⅳ ） sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce（NO3）6]^2- complex is the main adsorbed Ce（Ⅳ） species. Oxidation of sorbents by adsorbed Ce （ Ⅳ ） species resulting in Ce （ Ⅲ ） release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce（ Ⅳ ） reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce （ Ⅳ ） from La （ Ⅲ ） and Y （ Ⅲ ） was carried out from 6 mol·L^-1 nitric acid with PVP based anion exchanger. Reasonable Ce （Ⅳ） breakthrough capacity （0.7 mol·kg^-1 PVP） was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce （Ⅲ） leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L^- 1 nitric acid was successful （recovery 100% ± 4% ） and Ce solution of high purity （ 〉 99.97% ） with respect to La and Y content was gained.

Rare earth permanent magnets Sm_2(Co, Fe, Cu, Zr)_17 for high temperature applications

Sintered Sm（Coba1FexCu0.1Zr0.03）7.5 （x=0.09-0.21） permanent magnets with higher Fe content were found to have higher remanence Br and maximum energy product （BH）max at room temperature. Br and （BH）max reached maximum of 0.96 T and 176.7 kJ/m^3, respectively at room temperature when the Fe content x reached 0.21. However, the intrinsic coercivity Hci at room temperature increased gradually when the Fe content x increased from 0.09 to 0.15, but when x further increased to 0.21, Hcidecreased. Hci attained its peak value of 2276.6 kA/m with Fe content x=0.15 at room temperature. For magnets with x=0.15, Br, （BH）max and Hc1 reached 0.67 T, 81.2 kJ/m^3 and 509.4 kA/m at 500 ℃, respectively, showing good high temperature stability, which could be used in high temperature applications.

Development of Auto Exhaust Catalysts and Associated Application of Rare Earths in China

There are at least three obvious trends in the developments of automotive market in China: the evolution of emission standards from Euro Ⅱ to Euro Ⅲ, the demand of lean-burn gasoline engine and the time of diesel vehicles. The latest application and advances of exhaust catalysts by Chinese researchers, using some high effcient, economical and durable methods to meet these changes in emission regulations laws and engine technologies, were described. Rare earth oxides, such as lanthana, ceria-based solid solutions and perovskite-type oxides, are widely used as excellent promoters for thermal stability, oxygen storage capacity and oxidation/reduction activity in these catalysts. Four phases in the development of the auto exhaust catalyst industry in China since the mid 1970s were reviewed. It is argued that China will become the center of global auto exhaust catalysts industry in the next decades with its economic, technical and environmental incentives, which greatly depends on the research and development of rare earth.

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....