Molecular Design and Electronic Structure of Polynuclear Rare Earth Complexes and Clusters

Studies on the electronic structure,molecular design,syntheses of some novel series of tetranuclear rareearth complexes in our laboratory have been reviewed.Spin-unrestricted localized INDO method was used tocalculate the electronic structure and the chemical bonding in the typical rare earth cluster Sc[Sc_6Cl_(12)Co]wasdiscussed.     

Magnetic Properties of the Nitrides of R_2Fe_(17)CN_x

The carbon and nitrogen atoms can be introduced into the R_2Fe_(17) structure by a proper heat treatment.The crystallographic and intrinsic magnetic properties of a series of R_2Fe_(17)CN_x,where R=Y,Sm,Gd,Tb,Dy,Er have been investigated by using X-ray diffraction technique and magnetic measurements.The interstitial car-bon and nitrogen atoms are found to have an effect of dilating unit cell volume,raising Curie temperature andsaturation magnetization,as well as enhancing uniaxial magnetocrystalline anisotropy.     

X射线荧光光谱分析稀土的研究进展（综述）

本文对近二十年来X射线荧光光谱仪在稀土分析方面的应用进行了综述。总结了环境、矿物、稀土富集物、单一稀土化合物、稀土金属、合金、稀土功能材料以及过程分析中稀土元素的X射线荧光光谱分析方法,检测方法涉及钢铁、有色金属、石油化工、地质、生物、电子材料等领域。展望了X射线荧光分析方法在稀土行业的应用前景。     

2,5-二巯基-1,3,4-噻二唑稀土有机配合物的合成及表征

用２,５－二巯基－１,３,４－噻二唑与三环戊二烯基或三（甲基环戊二烯基）稀土配合物反应,合成了五个分子内含Ｌｎ－Ｓ与Ｌｎ－Ｎ配键的稀土金属有机配合物。这些配合物均经过元素分析、红外光谱及质谱表征。有关数据表明,它们都是二齿配位的双核配合物。     

我国稀土化合物产业现状和展望

从我国稀土资源特点出发，介绍了我国稀土化合物的主要生产工艺和企业状况、单一或混合稀土化合物、特殊物理性能的稀士化合物和复合稀土化合物等稀土化合物产品的生产、研发及应用情况。预测了稀土化合物产业的发展趋势，并提出我国在该领域应加强应用产品研究开发，特别是Ce、La、Y、Pr等稀土元素的应用研究，保持稀土元素的消费平衡，扩大应用领域：提高企业自动控制水平，改善产品的稳定性和一致性；注意保护生态环境。     

Quantum Chemical Calculation on the Structures and Electronic Properties of Phosphonate Ester as Rare Earth Extractants

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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.     

Effect of Interstitial Atom Nitrogen on Properties of RE2Fe17 Compounds

The electronic structure and atomic magnetic moments of clusters NdFe6, NdFe6N3 and Fe8 with a dumbbell atom-pair in rare earth-transition element compounds NdEFe17Nx(x=0, 3) were studied by spin-polarized MS-Xα method. The results are as follows: There are three negative exchange couplings between Fe(c) and Fe(f) atoms in Nd2Fe17, which occur at their odd parity orbitals. Compared to the results of α-Fe calculated by the MS-Xα method, the low Curie temperature of compounds RE2Fe17 can be explained satisfactorily. (2) There is only one weaker negative exchange coupling orbital leaving in between Fe(c) and Fe(f) sites in Nd2Fe17N3. These results may be helpful for understanding the effect of interstitial atom M(M=N, H or C) in Fe2Fe17Mx on Curie temperature. The other key factors affecting the Fe-Fe exchange coupling in Fe2Fe17 compounds were also discussed.     

稀土金属基准晶形成规律研究及预测

研究了原子尺寸因数和电子因素对准晶形成的影响。利用原子尺寸因数和电子因素构成键参数坐标系统，对稀土族13个金属（La，Ce，Pr，Nd，Sm，Eu，Gd，Tb，Dy，Ho，Er，Yb，Ln）基，已有实验结果的55个准晶进行了系统的研究。研究结果表明：在键参数图中，准晶合金形成区与非形成区明显区分开，准确率为92．73％，并且区分边界可用一条椭圆函数曲线描述，椭圆曲线方程为：（x-m）^2/c^2＋（y-n）^2/d^2=1,椭圆曲线参数m，n，c，d可由基体元素的相关参数确定，同时对可能存在的新的二元准晶进行了预测。该方法为定性研究及寻找新型稀土金属基准晶合金开辟了一条新的途径，在材料研究领域具有理论指导意义。     

铸造铝硅合金中硅相变质机制的电子理论研究

通过计算机编程构造出了Al-Si铸造合金中Si(金刚石结构)相(111)表面及稀土导致的(111)孪晶表面的原子结构模型，利用连分敷方法计算了稀土处于表面及孪晶表面这两种位置时的电子结构。稀土原子处于孪晶表面时的结构能明显比处于Si(111)表面大，说明稀土原子容易占据孪晶表面的位置；稀土原子处于孪晶界时的环境敏感镶嵌能比处于表面小，说明稀土处于孪晶表面时比较稳定，同时原子间的键级积分计算也表明稀土能够占据孪晶表面的位置且在此处较稳定。这就从电子层次解释了稀土导致孪晶的事实，阐明了稀土在Al-Si铸造合金中的变质机制。     

镧系元素高氯酸盐苯丁基亚砜配合物的合成与表征

本文以稀土高氯酸盐ＲＥ（ＣｌＯ_４）_３ｎＨ_２Ｏ（ＲＥ＝Ｌａ~（３＋）、Ｃｅ~（３＋）、Ｐｒ~（３＋）、Ｎｄ~（３－）、Ｓｍ~（３－）、Ｅｕ（３＋），ｎ＝６～７）与苯丁基亚砜ＰＢＳＯ（Ｃ_６Ｈ_５Ｃ_４Ｈ_９）在无水乙醇体系中合成出六个新配合物，并对配合物进行了元素分析，稀土离子含量测定，配体ＰＢＳＯ含量测定ＣｌＯ_４~－含量测定、ＩＲ谱、导电、ＴＧ－ＤＴＡ分析及Ｘ－射线粉末衍射。确定了配合物的组成为［ＲＥ（ＢＰＳＯ）_７（ＣｌＯ_４）］（ＣｌＯ_４）_２，配位数为８，电解质类型为１：２。     

Effect of Yttrium on Mechanical Properties and Microstructure of Ceramets

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Effect of Rare Earth Element Ce on Microstructure and Properties of Aluminum Rod for Electrical Purpose

The effect of rare earth element Ce on microstructure, electrical conductivity and mechanical properties was studied.Using optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffractometer, the microstructure and phase composition of aluminum rod for electrical purpose were measured and analyzed.The results indicate that rare earth element Ce can considerably refine grain size of aluminum rod for electrical purpose,improve the regular distribution pattern of the impurity, such as silicon and iron which present in the aluminum matrix,form stable metal compound with pernicious impurity.This metal compound precipitates on the crystal boundary.As a result, the solid solubility of impurity in aluminum reduce, and the electrical conductivity of aluminum rod for electrical purpose is improved.It is found that the mechanical properties of aluminum rod for electrical purpose are improved by rare earth element in certain range of RE addition.     

Effect of rare-earth doping on adsorption of carbon atom on ferrum surface and in ferrum subsurface: A first-principles study

The adsorption of carbon atom on Fe surface and in Fe subsurface with and without rare earth (La and Ce) substitution in the surface layer and subsurface layer was studied by first-principles calculations. The carbon atom is predicted to adsorb at hollow and long bridge site on Fe(100) and Fe(110), respectively. However, the carbon atom shifts to occupy preferentially hollow site on both Fe(100) and Fe(110) with rare earth atom doping at surface layer. The lower adsorption energies involved with stronger adsorption abilities were obtained for carbon atoms on Fe surface with rare earth doping at surface layer, which was determined by the electronic structure of the surface atoms. The La atom was pulled out the surface after carbon adsorption due to strong interaction of La–C, which is consistent with the more charge transfer. In the subsurface region, the carbon atom prefers to occupy at octahedral site with rare earth doping at surface layer in Fe slab. These strong adsorption energies of the carbon atoms on Fe surface and in Fe subsurface with rare earth pose relevant insights into the interaction between carbon and rare earth, which helps to understanding the influence mechanism of rare earth in carburizing.     

Expression of the leptin receptor in human leukaemic blast cells

The highly conserved residue F208 in protein R2 of E. coli ribonucleotide reductase is close to the binuclear iron center, and found to be involved in stabilizing the tyrosyl radical Y122. in wild type R2. Upon the reconstitution reaction of the mutant R2 F208Y with ferrous iron and molecular oxygen, we observed a new EPR singlet signal (g = 2.003) formed concomitantly with decay of the transient tyrosyl radical Y122. (g = 2.005). This new paramagnetic species (denoted Z) was stable for weeks at 4 degrees C and visible by EPR only below 50 K. The EPR singlet could not be saturated by available microwave power, suggesting that Z may be a mainly metal centered species. The maximum amount of the compound Z in the protein purified from cells grown in rich medium was about 0.18 unpaired spin/R2. An identical EPR signal of Z was found also in the double mutant R2 F208Y/Y122F. In the presence of high concentration of sodium ascorbate, the amounts of both the transient Y122. and the new species Z increased considerably in the reconstitution reaction. The results suggest that Z is most likely an oxo-ferryl species possibly in equilibrium with a Y208 ligand radical.     

稀土在12MnReHP钢中的应用

通过大生产试验,阐述了稀土在钢中的作用,确定了稀土金属合理的加入方法和加入量,通过对比,检验分析了１２ＭｎＲｅＨＰ钢中夹杂物数量、形状、分布以存在形式。     

Synthesis and Thermal Decomposition Mechanism of Rare Earth Benzoates

Rareearthbenzoatesareakind0fstablecompounds.Theco0rdinationcomP0undsf0rmedbyrareearthandcarboxylicacidshaveunusualstructuresandinterestinglundnesceniProperties.Bymeansoff0rmingc0njugaedcomplexes,rareearthmetalsandcarb0xylicacidscanf0rmnetorlayerp0lymerandchangetheirlundnescentprop-erties.S0merareearthcomplexeshavebeenap-Pliedinagricultureaslight-transfeedngmaeri-al8-Althoughthermaldecompositi0nmechanismofrareearthbenz0ateshasbeenreported,itdealswith0nlys0lidphaseproducts["'1,litdeab0utgasPha…     

稀土粉体性能的评价体系(Ⅰ)： 晶粒与表面特性的评价

稀土粉体(氢氧化稀土、稀土碳酸盐、稀土草酸盐、稀土氧化物和氟化物等)的颗粒性能方面的指标对稀土新材料的开发具有重要意义。晶粒特性、表面特性、颗粒特性、颗粒群特性和应用特性等五方面构成了稀土粉体性能的评价体系。本文对晶粒特性和表面的评价进行了讨论。晶粒大小和晶体结构是描述晶粒特性的两个指标,比表面积、表面电位、比表面能和表面亲和性是描述表面特性的四个指标。     

变价稀土氧化物对催化剂性能的影响

本文从原子结构分析了变价稀土元素原子的结构特点 ,从机理上分析了变价稀土氧化物对催化剂原子氧化价的稳定性、贮氧能力和热稳定性等性能增强的根源 ,从理论上深入认识了稀土氧化物的助催化作用。     

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.