Pretreatment of Chrysotile With Rare Earth Compounds Lowered Its Cytotoxicity by Lessening Surface Charges

Pathological effects of asbestos are probably dependent on the special surface properties of the fibers, such as surface charge, surface metal ions. The present study was designed to determine whether the pretreatment of chrysotile asbestos fibers (CAF) with rare earth compounds (REC) solution can reduce their pathogenicity. The results showed that REC-pretreated CAF induced less nitrogen oxide (NO) production by alveolar macrophages (AM). In addition, the pretreatment lowered the capacity of hemolysis and the methylene blue (MB) adsorption of the native CAF. These findings suggested that the pretreatment of CAF with REC solution reduced the in vitro toxicity of CAF by lessening its surface charges. Nevertheless, the pathogenicity and the carcinogenicity of REC-pretreated CAF in vivo remain to be investigated.

Rare Earth Compounds in Cemented Carbides with Trace Rare Earth Additions

The morphology,structure and distribution of the rare earth compounds in the YG8R.YT5R and YT14R cemented carbides with additions of trace light rare earths were studied with an analytical electron microscope. The particles of the rare earth compounds in these alloys are all spherical and distribute at interfaces between the Co-cement phase and WC hard phase or(TiW)C solid solution,and in the(TiW)C solid solution.In the YG8R and YTI4R alloys,the rare earth compound is RE_2O_3 with a bcc structure,while in the YT5R alloy. the rare earth compound is RE_2O_2S with a hcp structure.

Prediction of Heat of Fusion of Rare Earth Compounds from Binary Phase Diagrams

Based on the thermodynamical principle the new formula for calculation of heat of fusion and its error have been derived from binary phase diagrams which could be classified to eutectic,solid solution,degenerate eutectic and involving a compound phase diagram and so on.Using these formulae heats of fusion of some rare earth ox- ides have been predicted.

Wear-Resistance Performance of ZA-27 Alloys Reinforced by Rare Earth Compounds

The morphology of ZA-27 alloy reinforced by RE compounds and its wear-resistance were studied. It is found that some nodular second phases appear due to the addition of Si and RE, which can disperse in grain boundaries or between dendrite crystals so that the alloy has been refined. Energy spectrum analysis of scanning electron microscope shows that the second phases are complex compounds containing RE, Al, Zn and Si. The micro- hardness test indicates that micro-hardness values of the compounds are higher than those of the matrix. The wear-resis tance of ZA-27 alloy reinforced by RE compounds is 4 times as high as that of ZA-27 alloy and also higher than that of ZA-27 alloy containing Si phase. The impact toughness of the alloy containing RE and Si is higher than that of the alloy containing Si.

Theoretical Study of the Rare Earth Compounds Lafe_13-Xt_x(T= Cr, Cu, Ga, Mn, Ni) and Curie Temperature Variation

The phase stability and site preference of the intermetallics LaFe13-xTx (T=Cr, Cu, Ga, Mn, Ni) with NaZn13-type structure have been investigated by lattice inversion potentials. The calculated results indicate that each of the stabilizing elements Cr and Mn significantly decreases the cohesive energy of LaFe13-xTx and plays a role in stabilizing the 1:13 structure. The calculated lattice parameters of LaFe13-xTx (T=Al, Si) compounds are in good agreement with the experimental data. Qualitative analyses are carried out on the behavior of the Curie temperature and magnetocrystalline anisotropy. All the results indicate that the pair potentials based on the lattice inversion method can effectively give a deeper insight into the structure and property of complex materials.

Study of the Coarse Blocky Compounds in the As－cast 7075 Aluminium Alloys Containing Rare Earth Elements

The coarse blocky compounds in the as-cast 7075 aluminium alloys containing rare earth elements, neodymium, cerium or mischmetal were investigated by means of transmission electron microscope with EDX and scanning electron microscope. The blocky compounds in these alloys were identified as rare earth compounds, (Cr, Ti)2 RE (Al, X)20 (X is magnesium, copper and zinc),body-centred cubic, with 184 atoms to the unit cell , lattice parameter 1.453￣1. 458 nm, Vickers hardness 4000￣5600 MPa and calculated density 3400 kg/m3. The results show that the amount of blocky compounds in the alloys decreases with decreasing of Ti and Cr content or with increasing of cooling rate during solidification.

Study on Simultaneous Catalytic Reduction of Sulfur Dioxide and Nitric Oxide on Rare Earth Mixed Compounds

CeO2/γ-Al2O3, La203/γ-Al2O3, CeO2-La203/γ-Al2O3 and CeO2-La2O3, which were prepared by impregnating in certain ratio, were used as the catalysts for the reduction of SO2 and NO by CO. Separate and simultaneous removal of SO2 and NO over LaEO3/γ-Al2O3, CeOE/γ-Al2O3, CeOE-LaEO3/γ-Al2O3 were investigated. The phase characteristics of catalysts were also analyzed by X-ray diffraction. The result shows that the conversions of SO2 and NO are above 98 % over CeOE/γ-Al2O3 and CeOE-LaEO3/γ-Al2O3. After SO2 is added in the NO-CO-N2 system （NO ：SO2 = 1：2 - 1 ： 3）, the conversions of SO2 and NO are both above 98%. Furthermore, it is found that CeO2-La2O3 with various ratios has different activity for the simultaneous reduction of SO2 and NO.

Review of magnetic properties and magnetocaloric effect in the intermetallic compounds of rare earth with low boiling point metals

The magnetocaloric effect （MCE） in many rare earth （RE） based intermetallic compounds has been extensively in- vestigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal（s） （Zn, Mg, and Cd）. Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi2B2C superconductors is also presented.

Analysis of Valence Electron Structure in Compound Layer of Steel 42CrMo Plasma Nitrided with Rare Earth Addition

The valence electron structure (VES) in compound layer of steel plasma-nitrided at 560°C with rare earth (RE) addition was calculated based on the empirical electron theory (EET) of solids and molecules and BLD method. The results show that the presence of RE atoms diffused into surface layer leads to an increase of phase structure factor, which explains the catalyzing and micro-alloying effects of RE.

Lubricity of Rare Earth Compounds in Oil

The lubricities of fifteen rare earth compounds of lanthanum, praseodymium, samarium, europium and gadolinium are evaluated on a four ball tester and compared with that of ZDDP(Zinc Dialkyldithiophosphate). Results show that some of rare earth compounds provide much better lubricities than ZDDP, and the hexagonal type of rare earth metal compounds exhibit better lubricites than the body centered cubic type of metal compounds.

STUDY ON SYNTHESIS,CHARACTERIZATION AND STRUCTURE OF A NEW RARE EARTH COORDINATION COMPOUND WITH BENZOIC ACID

In this paper,a new rare earth benzoate coordination compound,[TbL_3(HL)(H_2O)]_2 (HL=C_7H_6O_2=benzoic acid) is synthesized and characterized by elemental analysis DTA,TG,DTC,and IR spectra.The title compound crystallizes in triclinic,space.group P with a=9.148(1),b=11.460(2), c=13.506(2);α=112.76(1),β=91.83(1),γ=91.99(1)°;Z=1;V=1303.3.The final R factor is 0.0235.The rare earth ion is nine-coordinated to form a distorted monocapped square antiprism.

Study of Properties of Intermetallic Compounds of Rare Earth Metals by Artificial Neural Networks

The results of an expert system of lanthanide intermetallic compounds using artificial neural networks and chemical bond parameter method were reported. Two pattern recognition neural models, one for prediction of the occurrence of 1 : 1 lanthanide intermetallic compounds with CsClstructure and the other for prediction of congruent or incongruent melting types, were developed. Four regression neural models were also developed for prediction of melting point of these compounds. In order to get rid of overfitting, cross-vahdation method was used for the neural models. And satisfactory results were obtained in all of the neural models in this paper.

Preparation and Characterization of Layered Compound Zirconium Bis(monohydrogenphosphate) Intercalated with Rare Earth Complex

Layered compound zirconium bis(monohydrogenphosphate)(alpha-ZrP) intercalated with rare earth complex Eu(DBM)(3)phen was prepared. The pre-intercalation of p-methoxyaniline into alpha-ZrP makes the interlayer separation large enough to exchange PMA with europium complex, thus, the luminescent assembly was prepared. This was confirmed by X-ray diffraction, UV-visible spectra and elemental analysis. The fluorescence spectra and lifetime of the assembly were also presented.

STUDY ON THE COORDINATION COMPOUNDS OF RARE EARTHS WITH DIPEPTIDE-COORDINATION OF RARE EARTHS WITH DL-ALANYL-ALANINE

In this paper protonation constants of the title lisand and stability constants of its coordination compounds with rare earths have been determined by potentiometric titration at 25±0.1℃ and ionic strength of 0.10mol.dm^(-3)NaClO_4. The coordination of rare earths with DL-alanyl-alanine has been discussed. The stability of the coordination compound shows 'tetrad effect'. The position for yttrium shifts from its usual Bo-Er region to the vicinity of Tb.

Research and Development of Rare Earth Advanced Materials in China

China is rich in resources of rare earths(REs). Based on tremendous work, China has made great achievements in research and development of REs since 1980s, and the production of RE has won the leading position in the world. The application of RE elements in advanced materials have progressed significantly during the past years. The wide range of rare earth application in China has been reviewed and discussed in this paper, including the development of advanced RE materials (RE-Al alloys, rare earth nonferrous metal alloys, rare earth luminescent materials, rare earth hydrogen storage materials, rare earth permanent magnet and rare earth compounds used in agriculture, i.e., rare earth micronutrient fertilizer etc.) End the research of new RE materials (high T-c rare earth superconductor, rare earth electronic and photonic materials, rare earth ceramics and rare earth precious metal alloys). Finally, the further development works to be required are as follow: (1) to enhance the applied fundamental research, study the intrinsic properties of rare earth elements and develop less well known uses; (2) to undertake the applied research of median and heavy rare earth and find a way out of the unbalance of RE resources in the various applications; (3) to strengthen the applied research of RE element's in energy field, solving the energy-related, energy-saved and environmental problems.

SYNTHESIS AND IDENTIFICATION OF CONDUCTING POLYANILINE DOPED WITH RARE EARTH CHLORIDE

Polyaniline doped with rare earth chloride was synthesized in organic solvent and identified by elemental analysis and infrared spectroscopy. The experimental results show that there exists both doping and complexation at the same time in the resulting product. When pH4. Moreover, polyaniline doped with rare earth chloride exhibits better thermal stability than that doped with hydrochloric acid.

Study on Nanocrystalline Rare Earth Mg-Based System Hydrogen Storage Alloys with AB_3-Type

A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1). after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).

Analysis of Rare-Earth Phase in a W-Mo-Ni-Fe-Mn-La Heavy Alloy

Besides W-phase and Ni-phase, there is a micro new phase in W-Mo-Ni-Fe heavy alloy added with La and Mn. The micro phase can he extracted as an electrolytic residue by the following method: A mixture of the new phase and the Ni-phase is isolated when an alloy sample is electrolyzed in 5%NaOH+1% tartaric acid solution. And the new phase can be isolated alone when the mixture is electrolyzed in 10% acetylacetone +1%LiCl methanol solution. The result of the quantitative phase analysis indicates that the new phase is a complex oxide rich in La, W and Mn.The interfacial segregation of oxygen decreases and the binding force between W-Ni Phases increases because of the existence of the oxide. So the mechanical properties of the alloy are improved.

Synthesis and Properties of Rare Earth Complexes with p-Methoxybenzoyl-Benzoylmethane and / or Amines

p-Methoxybenzoyl-benzoylmethane(HA)and its complexes LnA_4QH and LnA_3·xH_2O(for Ln=La～ Yb,Q=n-tributyl amine,diethyl amine,hexahydropyridine)were synthesized and characterized by elemental analysis,molar conductivity measurement,infrared spectroscopy,UV-visible absorption spectroscopy,thermal analysis and ~1H NMR spectra.Possibilities of using praseodymium and europium complexes as shift reagent are also discussed.

Effects of La-Rich Rare Earth Alloys on Structure and Mechanical Properties of ZL101A Alloy

The effects of La rich rare earth alloys on structure and mechanical properties of ZL101A alloy in as cast, heat treated and remelted states were investigated. The appropriate quantity of the addition of RE alloys and the reasonable heat treatment parameters for integral casting wheel made by low pressure die casting have been suggested.