Electron Donating Property and Catalytic Activity ofPerovskite-type Mixed Oxides (ABO_3) Consisting of Rare Earth and 3d Transition Metals

The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have been correlated with the surface electron donor properties of these mixed oxides

Synthesis and Structures of A Series of Novel Rare Earth Transition Metal Sulfates

Seven new rare earth transition metal sulfates were synthesized by hydrothermal reactions under conditions slightly above the critical point of water. Their crystal structures were determined from single crystal X-ray data. The compositions of the new compounds can be represented by two general formulae ： REM （OH） 3 （SO4） and RE2M （OH） 3 （SO4） 2F （H2O） with RE = Gd, Tb, Dy ; M = Ni, Cu. Three different crystal structure types were found for the formula REM （OH） 3 （SO4）. The structures of the new compounds all feature infinite chains of REOn coordination polyhedra, which are connected to chains of CuO6 or NiO6 octabedra. The limited size range of the rare earth cations observed in these compounds is most likely because of interactions between the octabedral chains and the chains of REOn polyhedra. The new compounds are closely related to the known yttrium transition metal sulfates.

Infrared Polarizabilities of 3d-Transition and Rare-Earth Metals

A transition or rare-earth metal is modeled as the atom immersed in a jellium at intermediate electron gas densities specified by? rs=4.0. The ground states of the spherical jellium atom are constructed based on the Hohenberg-Kohn-Sham density-functional formalism with the inclusion of electron-electron self-interaction corrections of Perdew and Zunger. Static and dynamic polarizabilities of the jellium atom are deduced using time-dependent linear response theory in a local density approximation as formulated by Stott and Zaremba. The calculation is extended to include the intervening elements In, Xe, Cs, and Ba. The calculation demonstrates how the Lindhard dielectric function can be modified to apply to non-simple metals treated in the jellium model.

Magnetic Behavior of Some Rare-Earth Transition-Metal Perovskite Oxide Systems

Magnetic properties were investigated for the rare-earth 3d-transition metal oxides with the perovskite structure. Intriguing magnetic phenomena were reviewed for a few systems:magnetization peak effect in the titanates, magnetization reversal in the chromites and metallic ferromagnetism in the cobaltites. The results suggest an important role of the rare-earth ions for the magnetic properties of such complex oxides.

Fabrication and Characterization of Glass-Ceramics Doped with Rare Earth Oxide and Heavy Metal Oxide

Cordierite-based glass-ceramics with non-stoichiometric composition doped with rare earth oxide (REO_2) and heavy metal oxide (M_2O_3) respectively were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including compact density and apparent porosity, were examined to evaluate the sintering behavior of cordierite-based glass-ceramics. Results show that the additives both heavy metal oxide and rare earth oxide promote the sintering and lower the phase temperature from μ- to α-cordierite as well as affect the dielectric properties of sintered glass-ceramics. The complete-densification temperature for samples is as low as 900 ℃. The materials have a low dielectric constant (≈5), a low thermal expansion coefficient ((2.80～3.52)×10^(-6) ℃^(-1)) and a low dissipation factor (≤0.2%) and can be co-fired with high conductivity metals such as Au, Cu, Ag/Pd paste at low temperature (below 950 ℃), which makes it to be a promising material for low-temperature co-fired ceramic substrates.

Thermodynamics of Modifying Effect of Rare Earth Oxide on Inclusions in Hardfacing Metal of Medium-High Carbon Steel

The modifying effect of rare earth (RE) oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics. The thermodynamic analysis for inclusion formation shows that RE oxide can be reduced to RE element by carbon, then the RE element can react with oxygen and sulfur to form the RE oxide, RE sulfide and RE oxide-sulfide in hardfacing molten pool. The deoxidization and the desulphurization can be carried out and the liquid metal can be purified. In addition, RE oxide can also react with sulfur to form RE oxide-sulfide directly. Therefore, the harmful effect of sulfur can be decreased.

Hydrogen production from coke oven gas over LiNi/γ-Al_2O_3 catalyst modified by rare earth metal oxide in a membrane reactor

The performance of LiNi/γ-Al2O3 catalysts modified by rare earth metal oxide （La2O3 or CeO2） packed on BCFNO membrane reactor was discussed for the partial oxidation of methane （POM） in coke oven gas （COG） at 875 ℃. The NiO/γ-Al2O3 catalysts with different amounts of La2O3 and CeO2 were prepared with the same preparation method and under the same condition in order to compare the reaction performance （oxygen permeation, CH4 conversion, H2 and CO selectivity） on the membrane reactor. The results show that the oxygen permeation flux increased significantly with LiNiREOx/γ-Al2O3 （RE = La or Ce） catalysts by adding the element of rare earth especially the Ce during the POM in COG. Such as, the Li15wt%CeO29wt%NiO/γ-Al2O3 catalyst with an oxygen permeation flux of 24.71 ml·cm^-2·min^-1 and a high CH4 conversion was obtained in 875 ℃. The resulted high oxygen permeation flux may be due to the added Ce that inhibited the strong interaction between Ni and Al2O3 to form the NiAl2O4 phase. In addition, the introduction of Ce leads up to an important property of storing and releasing oxygen.

Kinetics of Glass Transition and Crystallization in Carbon Nanotube Reinforced Mg-Cu-Gd Bulk Metallic Glass

Mg65Cu25Gd10 bulk metallic glass and its carbon nanotube reinforced composite were prepared. Differential scanning calorimeter （DSC） was used to investigate the kinetics of glass transition and crystallization processes. The influence of CNTs addition to the glass matrix on the glass transition and crystallization kinetics was studied. It is shown that the kinetic effect on glass transition and crystallization are preserved for both the monothetic glass and its glass composite. Adding CNTs in to the glass matrix reduces the influence of the heating rate on the crystallization process. In addition, the CNTs increase the energetic barrier for the glass transition. This results in the decrease of GFA. The mechanism of the GFA decrease was also discussed.

Research progress in rare earths and their composites based electrode materials for supercapacitors

Supercapacitor is an imminent potential energy storage system,and acts as a booster to the batteries and fuel cells to provide necessary power density.In the last decade,carbon and carbonaceous materials,conducting polymers and transition metal oxide/hydroxide based electrode materials have been made to show a remarkable electrochemical performance.Rare-earth materials have attracted significant research attention as an electrode material for supercapacitor applications based on their physicochemical properties.In this review,rare earth metals,rare earth metal oxides/hydroxides,rare-earth metal chalcogenides,rare-earth metal/carbon composites and rare-earth metal/metal oxide composites based electrode materials are discussed for supercapacitors.We also discuss the energy chemistry of rare-earth metal-based materials.Besides the factors that affect the performance of the electrode materials,their evaluation methods and supercapacitor performances are discussed in details.Finally,the future outlook in rare-earth-based electrode materials is revealed towards its current developments for supercapacitor applications.

Using Atomic Microstates and Atomic Number Parity in Support of Lutetium and Lawrencium Classification as Transition Metals

Unlike other groups of elements, Group 3 constituency remains unsettled. This article argues that ground level microstates and atomic number parity suggest Sc-Y-Lu-Lr Group 3 membership.

Spontaneous Magnetic Transitions and Corresponding Magnetoelastic Properties of Intermetallic Compounds RMn_2Ge_2(R=Gd, Tb and Dy)

The spontaneous magnetic transitions and corresponding magnetoelastic properties of intermetallic compounds RMn2Ge2（R=Gd, Tb and Dy） were investigated by using the X-ray diffraction method and magnetic measurement. The results showed that the compounds experience two magnetic transitions, namely the second-order paramagnetic to antiferromagnetic transition at temperature TN（TN=368, 423 and 443 K for Gd Mn2 Ge2, Tb Mn2 Ge2 and Dy Mn2 Ge2, respectively） and the first-order antiferromagnetic-ferrimagnetic transition at temperature Tt（Tt=96, 80 and 40 K for Gd Mn2 Ge2, Tb Mn2 Ge2 and Dy Mn2 Ge2, respectively） as the temperature decreases. The temperature dependence of the lattice constant a（T） displays a negative magnetoelastic anomaly at the second-order transition point TN and, at the first-order transition Tt, a increases abruptly for Gd Mn2 Ge2 and Tb Mn2 Ge2, Da/a about 10^（-3）. Nevertheless, the lattice constant c almost does not change at these transition points indicating that such magnetoelastic anomalies are mainly contributed by the Mn-sublattice. The transitions of the magnetoelastic properties are also evidenced on the temperature dependence of magnetic susceptibility χ. The first-order transition behavior at Tt is explained by the Kittel mode of exchange inversion.

Broadband 1.53 μm emission in Er^(3+)-doped Ga-Bi-Pb-Ge heavy metal oxide glasses

We investigated the thermal stability and spectroscopic properties of the 1.53 μm emission from ^4I13/2→^4I15/2 transition of Er^3＋ ions in Er^3＋/Yb^3＋-codoped Ga-Bi-Pb-Ge heavy metal oxide glass for use in broadband fiber amplifiers. It was noted that the addition of GeO2 effectively enhanced the thermal stability of the heavy metal oxide glass studied. The emission peak located at approximately 1530 nm with a full width at haft-maximum of approximately 58 nm. The measured lifetime and the calculated emission cross-section of this transition were -3.2 ms and -10.3×10^-21 cm^2, respectively. As a result, Ga-Bi-Pb-Ge heavy metal oxide glasses were assumed to be potential host material for the 1.53 μm broadband optical fiber amplifiers.

Measurement of Residual Stress Field of Hardfacing Metal with RE Oxide and Its Numerical Simulation

The temperature and residual stress fields of a medium-high carbon steel, welded by a cracking resistance electrode with rare earth (RE) oxide, were measured by thermo-vision analyzer and X-ray stress analyzer respectively. Meanwhile, the martensitic transformation temperatures of matrix, hard-face welding (hardfacing) metal welded by conventional hardfacing electrode and that welded by cracking resistance electrode with RE oxide were determined. According to the experimental data and the thermo-physical, mechanical parameters of materials, finite element method (FEM) of temperature and stress fields was established. In this FEM, the effect of martensitic transformation on residual stress of hardfacing metal of medium-high carbon steel was taken into account. The results show that, by adding RE oxide in the coat of hardfacing electrode, the martensitic transformation temperature can be decreased, so that the residual tensile stress on the dangerous position can be decreased. Therefore, the cracking resistance of hardfacing metal can be improved.

Synthesis,Structure and Bonding Feature of New Metallic Zintl Phases RE_3Cu_3Sb_4(RE= Nd ,Sm ,Tb , Dy , Ho)

RE 3Cu 3Sb 4(RE=Nd, Sm, Tb, Dy, Ho) was synthesized by arc melting method and their crystal structures were characterized by powder X ray method. The compounds crystallize in cubic system, Y 3Au 3Sb 4 type, space group I43d (No.220), Pearson code cI40. The unit cell parameters are: Nd 3Cu 3Sb 4: a =0 96749(1) nm, V =0 90561(3) nm 3; Sm 3Cu 3Sb 4: a =0 96145(1) nm, V =0 88875(3) nm 3; Tb 3Cu 3Sb 4: a =0 95362(1) nm, V =0 86721(3) nm 3; Dy 3Cu 3Sb 4: a =0 95088(1) nm, V =0 85975(3) nm 3; Ho 3Cu 3Sb 4: a =0 9488(2) nm, V =0 8541(5) nm 3; Z =4. The structures are characterized by covalent bonded Cu Sb tetrahedra which form three dimensional networks by sharing corners. The rare earth atoms are distributed in the cages. The formula with the charge balance can be written as RE 3+ 3Cu 1+ 3Sb 3- 4 which are metallic Zintl phases having the weak metallic conductivity. The bonds have typical transitional features. General atomic coordination environment rules are followed. The unit cell parameters show the lanthanide contraction.

Selected multiferroic perovskite oxides containing rare earth and transition metal elements

Multiferroic materials are currently the subject of intensive research worldwide, because of both their fundamental scientific problems and also possible technological applications. Among a number of candidates in the laboratories, compounds consisting of rare earth and transition metal perovskite oxides have very unusual structural and physical properties. In contrast to the so-called type I multiferroics, ferroelectricity may be induced by magnetic ordering or by applying external fields. In this review, the recent progress on the experimental and theoretical studies of some selected type II multiferroics is presented, with a focus on the perovskite oxides containing rare earth and transition metal elements. The rare earth orthoferrite crystals, rare earth titanate strained film, and rare earthbased superlattices are systematically reviewed to provide a broad overview on their promising electric, magnetic, and structural properties. The recent experimental advances in single-crystal growth by optical floating zone method are also presented. First-principles investigations, either supported by experimental results or awaiting for experimental verifications, are shown to offer useful guidance for the future applications of unconventional multiferroics.

Effects of flaky rare earth oxide additives on the high temperature performance of nickel electrodes

Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...

Magnetocrystalline anisotropy and spin reorientation transition of DyMn_6Sn_6 compound

The spin-reorientation transition of intermetallic compound DyMn6Sn6 was investigated by applying the molecular field theory. The temperature dependence of easy magnetization direction of compound and the magnetic moment directions of Dy and Mn ions were theoretically calculated and they have good agreement with the experimental data. In the framework of single ion model, the temperature dependence of magnetocrystalline anisotropic constants K1R and K2R of Dy ion were also calculated. The results show that the fourth-order crystal field parameter, B 40, and the corresponding second-order magnetocrystalline anisotropic constant, K2R, of Dy ion must be taken into account in order to explain the spin-reorientation transition satisfactorily. The competition between K2R and K1R plays a key role in the spin-reorientation transition of DyMn6Sn6.

Lithofacies Phases Analysis of Cover Flux in Tundish for Rare Earth Treated Steel

Lithofacies structure of commercial cover flux and experimental slags were analyzed,and states of rare earth oxides in cover flux were studied. The results show that under the experiment conditions,the mineral structures of original slags are mainly the calcium feldspar,a lot of magnesium olivine and Fe-bearing silicate. Rare earth oxides in the cover flux exist mainly as rare earth silicates. When the content of rare earth oxides reaches a certain value,rare earth oxides precipitate in molten cover flux. It means that the solubility of rare earth oxides is limited. Rare earth oxides may be partly substituted for CaO to form rare earth-silicate which may increase with the basicity reducing.

Applications of Rare Earth Promoted Transition Metal Sulfides in Electrocatalysis

With the rapid consumption of fossil fuels and the resulting environmental problems,researchers are working to find sustainable alternative energy and energy storage and conversion methods.Transition metal sulfur compounds have attracted extensive attention due to their excellent electrical conductivity,low cost,adjustable components and good electrocatalytic performance.As an alternative to noble metal catalysts,they have emerged as a promising electrocatalyst.However,their low catalytic activity and poor stability limit their large-scale practical applications.Rare earth elements,known as industrial vitamins,are widely used in various fields due to their special redox properties,oxygen affinity and electronic structure.Therefore,the construction of rare earth promoted transition metal sulfides is of far-reaching significance for the development of catalysts.Here,we review the applications of various rare earth promoted transition metal sulfides in energy storage and conversion in recent years,which focuses on three ways in rare earth promoted transition metal sulfide,including doping,interfacial modification engineering and structural facilitation.As well,these materials are used in electrochemical reactions such as OER,HER,ORR,CO_(2)RR,and so on,in order to explore the important role of rare earth in the field of electrocatalysis,the future challenges and opportunities.