DETERMINATION OF TRACE AMOUNT OF 14 RARE-EARTH IMPURITIES IN HIGH-PURITY YTTRIUM-OXIDE WITH ICP-AES

A method of analysis of high purity yttrium oxide with ICP-AES was described with emphasis on the study of Y_2O_3 matrix effects. The results showed that the line intensities of ana]ytes decreased with the increase of Y_2O_3 concentration in solution because of following factors. (1) The presence of matrix resulted in the decrease of the amount of analytes reaching ICP. (2) Matrix Y_2O_3 entering the plasma decreased the excitation temperature of the plasma and depressed the ionization of analytes in the pl...

STUDY OF BIMETALLIC COMPLEXES OF RARE-EARTH LITHIUM - SYNTHESIS AND CRYSTAL-STRUCTURE OF THE (LACL)DME(MU-2-CL)5(MU-3-CL) (LA.DME)LI(THF)2

The reaction between LaCl_3 and LiCl in THF at room temperature, with hexane as precipitant and glycol dimethyl ether as complexing agent, has been studied. A complex with the composition of (LaCl)DME(μ_2-Cl)_5(μ_3-Cl)(La·DME)Li(THF)_2 has been synthesized, its structure was studied by single crystal X-ray diffraction technique. The diffraction intensities were collected at about —100℃. The complex belongs to the triclinic space group P1 with α=11.123(3), 6=16.564(5), c=8.653(3)A, α=95.16(3), β=...

SYNTHESIS AND CRYSTAL-STRUCTURES OF THE BIMETALLIC RARE-EARTH COMPLEXES AND STUDIES ON INSERTION MECHANISM OF DIENES POLYMERIZATION

The deepening of the studies on essentials of rare earth coordination catalyst brings about more and more reports on model compounds as active centre of the catalyst. Among them the most significant researches are those with identification of the crystal structures of compounds.

SYNTHESIS AND VIBRATIONAL SPECTRUM STUDIES OF RARE EARTH COMPLEXES WITH CYCLOHEXANE CARBOXYLIC ACID

The solid state complexes of trivalent lanthanid, yttrium and scandium with cyclohexane carboxylic acid have been isolated and characterized by IR and Raman spectroscopy. It was found that there are only chelated carboxylate groups in the scandium complex and that there are the chelated, bridged and chelate-bridged carboxylate groups in other rare earth complexes. The former is a mononuclear complex and the latter is a polynuclear polymer. The RE—O coordinate bonds possess the characters of convalent ionic ...

Geochemistry of rare earth elements in cobalt-rich crusts from the Mid-Pacific M seamount

Rare earth elements (RFEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimetric method. The results showed that they were hydrogenous crusts with average Sigma REE content of 2084.69 mu g/g and the light REE (LREE)/heavy REE (HREE) ratio of 4.84. The shale-normalized PEE patterns showed positive Ce anomalies. The total content of strictly trivalent REEs increased with water depth. The Ce content and LREE/HREE ratios in Fe-Mn crusts above 2000 in were lower than those below 2000 m. The change in RE E with water depth could be explained by two processes: adsorptive scavenging by setting matters and behaviors of REE in seawater. However, the Ce abundance took no obvious correlation with water depth reflects the constant Ce flux. The Cc in crusts existed mainly as Ce(IV), implying that the oxidative-enriching process was controlled by kinetic factors.

A preliminary study on fingerprinting approach in marine sediment dynamics with the rare earth elements

Locating the quantitized natural sediment fingerprints is an important work for marine sediment dynamics study. The total of 146 sediment samples were collected from the Shelf of the East China Sea and five rivers, including Huanghe (Yellow), Changjiang (Yangtze), Qiantang, Ou and Min River. The sediment grain size and the contents of rare earth elements (REEs) were measured with laser particle size analyzer and ICP-MS technology. The results show that absolute REE content (Sigma REE) and the concentration ratio of light REEs to heavy REEs (L/HREE) are different in the sediments among those rivers. There are higher REE contents in being less than 2 m and 2-31 mu m fractions in the Changjiang Estuary surface sediments. The REE contents of bulk sediment are dominated by the corresponding values of those leading size-fractions. Sigma REE of sediment is higher close to the estuaries and declines seaward on the inner shelf of the East China Sea (ECS). The L/HREE ratio has a tendency of increase southward from 28 degrees N. Hydrodynamic conditions plays a predominate role on spacial distributions of the surficial sediment's REE parameters. In some situations, the currents tend to remove the coarser light grains from initial populations, as well as the deposit of the finer heavy mineral grains. In other situations, the currents will change the ratio of sediment constituents, such as ratio between silts and clays in the sediments. As a result, the various values of Sigma REE or L/HREE ratio in different bulk sediments are more affected by the change of size-fractions than source location. Under the long-term stable hydrodynamic environment, i.e., the East China Sea Shelf, new sediment transport model based on the size and density gradation concept may help to understand the spatial distribution patterns of REE parameters.

Genesis of Th-230 excess in basalts from mid-ocean ridges and ocean islands: Constraints from the global U-series isotope database and major and rare earth element geochemistry

Based on Th-230-U-238 disequilibrium and major element data from mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs), this study calculates mantle melting parameters, and thereby investigates the origin of Th-230 excess. (Th-230/U-238) in global MORBs shows a positive correlation with Fe-8, P (o), Na-8, and F-melt (Fe-8 and Na-8 are FeO and Na2O contents respectively after correction for crustal fractionation relative to MgO = 8 wt%, P (o)=pressure of initial melting and F (melt)=degree of melt), while Th-230 excess in OIBs has no obvious correlation with either initial mantle melting depth or the average degree of mantle melting. Furthermore, compared with the MORBs, higher (Th-230/U-238) in OIBs actually corresponds to a lower melting degree. This suggests that the Th-230 excess in MORBs is controlled by mantle melting conditions, while the Th-230 excess in OIBs is more likely related to the deep garnet control. The vast majority of calculated initial melting pressures of MORBs with excess Th-230 are between 1.0 and 2.5 GPa, which is consistent with the conclusion from experiments in recent years that D (U)> D (Th) for Al-clinopyroxene at pressures of > 1.0 GPa. The initial melting pressure of OIBs is 2.2-3.5 GPa (around the spinel-garnet transition zone), with their low excess Ra-226 compared to MORBs also suggesting a deeper mantle source. Accordingly, excess Th-230 in MORBs and OIBs may be formed respectively in the spinel and garnet stability field. In addition, there is no obvious correlation of K2O/TiO2 with (Th-230/U-238) and initial melting pressure (P (o)) of MORBs, so it is proposed that the melting depth producing excess Th-230 does not tap the spinel-garnet transition zone. OIBs and MORBs in both (Th-230/U-238) vs. K2O/TiO2 and (Th-230/U-238) vs. P (o) plots fall in two distinct areas, indicating that the mineral phases which dominate their excess Th-230 are different. Ce/Yb-Ce curves of fast and slow ridge MORBs are similar, while, in comparison, the Ce/Yb-Ce curve for OIBs shows more influence from garnet. The mechanisms generating excess Th-230 in MORBs and OIBs are significantly different, with formation of excess Th-230 in the garnet zone only being suitable for OIBs.