Significantly improved high k dielectric performance: Rare earth oxide as a passivation layer laminated with TiO2 film

In order to achieve a super gate dielectric performance,rare earth oxides featuring for large band gap,good thermodynamic stability and relatively high k value were selected to be laminated with TiO₂ film to prepare bilayer dielectric films.As an example,the microstructure,morphology,band gap structure and electrical performance of TiO₂-Y₂O₃ bilayer films were systematically investigated.Results show that stacking sequence of TiO₂ and Y_...     

Advances in gas sensors of tetrapyrrolato-rare earth sandwich-type complexes——Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

In recent years,sandwich-type rare earth tetrapyrrole derivatives,have attracted more and more attention as material for conductimetric sensors.They have not only great chemical stability and processability,but also flexible molecular structure,which is a key to adjustable semiconductor properties.In this mini review,we focus mainly on the development of tetrapyrrolato-rare earth sandwich-type complexes as the semiconducting active layer in the gas sensors published in the last ten years(2010-2020).The main part includes two sections.In the single component gas sensing of sandwich rare earth tetrapyrrole complexes,we describe the influence factors of the single-component semiconducting active layer on the sensing performance of tetrapyrrolato-rare earth sandwich-type complexes,including substituents,central metals and π-conjugate systems.In the multi-component gas sensors,the synergistic effect between tetrapyrrolato-rare earth sandwich-type complex and other materials on improving sensitivity and conductivity has been discussed briefly.     

Advances in Rare Earth Application to Semiconductor Materials and Devices

The development of rare earths (RE) applications to semiconductor materials and devices is reviewed. The recent advances in RE doped silicon light emitting diodes (LED) and display materials are described. The various technologies of incorporating RE into semiconductor materials and devices are presented. The RE high dielectric materials, RE silicides and the phase transition of RE materials are also discussed. Finally, the paper describes the prospects of the RE application to semiconductor industry .     

Use of rare earth elements in single-atom site catalysis:A critical review——Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Rare earth metals are strategic resources with potential applications in optics,metallurgy and catalysis.In recent years,single-atom site catalysts(SASCs) have attracted increasing attention owing to their 100%atom efficiency and unique catalytic performances.Over the past decade,rare earth elements,including rare earth metals and their oxides,have shown great potential in SASCs.However,systematic analyses of data are still handful.In this mini-review,the use of rare earth metals and their oxides in SASCs was summarized and the results are discussed.A particular focus was paid to the synthetic strategies,characterization of rare earth-containing SASCs,and applications as catalysis supports,promoters and active sites.Current issues faced by rare-earth metals and their oxides in SASCs,as well as future prospects were also provided.     

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.However,all samples showed high dielectric constant in broad frequency range(10 MHz).The cutoff frequency(f0) was remarkably shifted to higher frequency from 13 MHz(pure CCTO ceramics) to 80 MHz(Gd-doped CCTO ceramics).Meanwhile,the dielectric loss tangent rapidly decreased approximately 10 times.These improvements of dielectric properties by rare earth doping are very useful in wide frequency chip capacitor and LTCC devices.     

Progress of Flotation Reagents of Rare Earth Minerals in China

The development and application of several flotation reagents of rare earth minerals in China since 1960s and their performance were described. Furthermore, the development trends of flotation reagents of rare earth minetttla were discussed.     

Optical Absorption Properties of Electron Beam Evaporated a-Si_(1-x)Gd_x Films

Optical absorption properties of electron beam evaporated a-Si films(a-Si_(1-x)Gd_x films)are studied forvarious composition x.It is shown from the experimental results that variation of chemical composition in thiskind of materials will lead to a change in near infrared absorption.For 0.1 at%相似文献   

RARE EARTH DISSOLVED IN SOLID SOLUTION OF STEEL AND ITS EFFECT ON MICROSTRUCTURE

The amounts of rare earth in the solid solution in steel 16Mn were determined by means of inductivecoupling plasma(ICP)spectroscopy.While the RE/S ratio was less than 1.9,the amounts of rare earth insolid solution were not more than 8 ppm,which rised slightly with the increase of the rare earth content in thesteel.While the RE/S was more than 1.9,MnS disappeared completely in the steel and the amounts of rareearth in solid solution increased rapidly with the increasing of the rare earth content.The solubility of ceriumin steel 16 Mn(St 52)is less than 0.011 wt% at room temperature.The results also indicate that rare earth insolid solution can reduce the amount of pearlite and increase that of ferrite and its mierohardness.The rela-tionship between microhardness(Hv)and the amount of rare earth in solid solution can be expressed by theequation of Hv=117 7 RE(ppm).     

Preparation and Luminescence Properties of LB Films Based on 4-Hexadecyloxybenzoic Terbium

LB films of 4-hexadecyloxybenzoic-terbium by using the subphase containing Tb^3 were prepared. The mono-layer behavior of 4-bexadecyloxybenzoic acid (HOBA) on the subphase containing rare earth ions was studied. IR and UV spectra show that the rare earth ions were bound to carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The luminescence spectra show that the LB films have the fine luminescence properties, and the LB films emit strong luminescence under UV light irradiation.     

Doping Effects of Rare Earth on Dielectric Properties of Fine－Grained BaTiO3－Based Ceramics

The doping effects of rare earth oxides Ho2O3 and Er2O3 on dielectric properties of BaTiO3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho2O3 and Er2O3 were added to BaTiO3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites.Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat.Meanwhile, the dielectric strength Eb becomes higher.     

Effect of hydroxyl groups on hydrophilic and photocatalytic activities of rare earth doped titanium dioxide thin films

Rare earth(Y, La and Nd) doped TiO2 thin films were prepared on glass slides by sol-gel method. The photocatalytic decomposition of methylene blue in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of hydroxyl groups on hydrophilic and photocatalytic activities were investigated by means of techniques such as X-ray diffraction(XRD), atomic force microscopy(AFM), Fourier transform infrared(FTIR), optical contact angle, UV-Visible spectroscopy and VIS spectroscopy. The results showed that an appropriate doping of rare earth could cause the TiO2 lattice distortion, inhibited phase transition from anatase to rutile, accelerated surface hydroxylation and produced more hydroxyl groups, which resulted in a denser surface and smaller grains(40–60 nm), and a significant improvement in the hydrophilicity and photoreactivity of TiO2 thin films. The optimal content of rare earth was between 0.1 wt.% and 0.3 wt.%. Moreover, the modification mechanism of rare earth doping was also discussed.     

Study on vacuum ultraviolet spectra of amorphous Er_2O_3 films on Si（001） substrates

Amorphous Er2O3 films have been fabricated on p-type Si(001) substrates using radio frequency magnetron sputtering technique. Vacuum ultraviolet spectra were employed to investigate the samples. An optical gap of 6.17 eV for Er2O3 films was obtained from the ab-sorption coefficient spectra. A possible reason was put forward to explain the inconsistent results about the band gap of Er2O3 in literatures. Emission spectra exhibited a strong emission band at 494 nm with the incident ultraviolet light of 249 nm. The observed high density of emission bands of Er2O3 films in the visible wavelength indicated that Er2O3 films could be used in Si solar cells for increasing conversion efficiency.     

Multiferroic and in-plane magnetoelectric coupling properties of BiFeO_3 nano-films with substitution of rare earth ions La~(3+) and Nd~(3+)

Single-phase multiferroic BiFeO_3 and Bi_(0.9)(La/Nd)_(0.1)FeO_3(doped with rare earth ions La~(3+) and Nd~(3+)) films grown on(111)-Pt/Ti/SiO_2/Si substrate were prepared via sol-gel method and a subsequent rapid thermal process. The phase composition, microstructure, ferroelectric, dielectric, ferromagnetic properties were investigated, and meanwhile, the in-plane magnetoelectric(ME) coupling effects of the films were reported and studied for the first time in this work. Structural characterization by X-ray diffraction and scanning electron microscopy showed that both BiFeO_3 and Bi_(0.9)(La/Nd)_(0.1)FeO_3 exhabited a rhombohedral structure with(111) preferred orientation. The results of the physical properties indicated that the introduction of rare earth ions improved significantly the polarization, magnetization and dielectric properties than the undoped BiFeO_3 crystals, and it enhanced effectively the in-plane ME coupling(the ME coupling coefficient αE increased from 0.13 in the pure BiFeO_3 to 0.21 in Bi_(0.9)La_(0.1)FeO_3 and 0.34 V/(Oe·cm) in Bi_(0.9)Nd_(0.1)FeO_3). The mechanism of these phenomena was investigated systematically.     

Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...     

Preface

<正>The International Conference on RARE EARTH MATERIALS(REMAT),which was organized in Wroc?aw in Poland on 26-28 April,2013 for the third time has undertaken the most recent aspects of novel rare earth materials,their applications and the problems with Rare Earth Elements(REE)supply.The conference was divided into three thematic sessions in which the leading issues were:the recycling of materials containing rare earth ions,mining these rare earth metals and the application of their ions in optical and magnetic materials.It     

China Limits the Mining Quantity of Tungsten and Rare Earth

Based on a notice issued by the Ministry of Land Resources, China's tungsten mining quantity in 2006 will be controlled to 59,060 tons in concentrates form, which include 4,250 tons of recycled tungsten. And the rare earth mining quantity in 2006 will also be controlled to 86,620 tons (REO) including 8,320 tons of heavy rare earth and 78,200 tons of light rare earth.     

Formation of intermetallic compound at interface between rare earth elements and ferritic-martensitic steel by fuel cladding chemical interaction

The intermetallic compounds formation at interface between rare earth elements and clad material were investigated to demonstrate the effects of rare earth elements on fuel-cladding chemical interaction(FCCI)behavior.Mischmetal(70Ce-30La)and Nd were prepared as rare earth elements.Diffusion couple testing was performed on the rare earth elements and cladding(9Cr2W steel)near the operation temperature of(sodium-cooled fast reactor)SFR fuel.The performance of a diffusion barrier consisting of Zr and V metallic foil against the rare earth elements was also evaluated.Our results showed that Ce and Nd in the rare earth elements and Fe in the clad material interdiffused and reacted to form intermetallic species according to the parabolic rate law,describing the migration of the rare earth element.The diffusion of Fe limited the reaction progress such that the entire process was governed by the cubic rate law.Rare earth materials could be used as a surrogate for high burnup metallic fuels,and the performance of the barrier material was demonstrated to be effective.     

Rare Earth Industry in Baotou Hi-tech Zone Quickened the Pace of Transition & Upgrading

<正>For the rare earth industry which is now in an inactive period,the recent benefits granted to the Rare Earth hi-tech Zone brought new hope to the development of the entire industry like a waft of spring breeze.In June this year,the rare earth industry transitionupgrading pilot implementationplan of Baotou City received approval from the Finance Ministry and the MIIT.Within 3 years,     

Humidity sensing properties of La^3＋ and K^＋ co-doped Ti0.9Sn0.1O2 thin films

The humidity sensing properties of La3+ and K+ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of thin films were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It was found that the addition of rare earth ion La3+ and alkali ion K+ was beneficial for improving the humidity sensitive properties of the samples and La0.003K0.5Ti0.9Sn0.1O2 sintered at 500 ℃ for 4 h showed the best humidity sensing properties. The impedance of this thin film decreased from 109 to 104 Ω with excellent linearity in the humidity range of 11%-95%. Narrow hysteresis loop, prominent stability and high sensitivity were obtained. The effects of dopant con-tent and doping mechanism on humidity sensitivity were also discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystalline and influence of K+ on the decrease in the intrinsic resistance of the materials, and increase in the number of wa-ter adsorption sites.     

Research progress of rare earth composite shielding materials

With the rapid development of nuclear technology,nuclear protection has received extensive attention.As an important strategic resource,rare earth plays an important role in the field of nuclear shielding materials.In this review,the shielding principles of rare earth materials are first introduced.According to the type of matrix,the characteristics and current research status of metal-based,inorganic nonmetallic-based and polymer-based rare earth shielding materials are reviewed.Meanwhile,the f...