LUMINESCENCE AND ENERGY-TRANSFER OF RARE-EARTH-METAL IONS IN MG2Y8(SIO4)(6)O-2

The photoluminescence of Ce3+, Tb3+ and Sm3+, and energy transfer from Ce3+ to Tb3+, Dy3+ and Sm3+ in Mg2Y8(SiOd(4))(6)O-2 are reported and discussed. The Ce3+ ion shows blue luminescence under UV excitation, and occupies simultaneously the 4f site and 6h site in the host lattice. The optimum concentrations for the D-5(3) and D-5(4) emissions of Tb3+ and the (4)G(5/2) emission of Sm3+ are determined to be 0.04, 0.20 and 0.10 mol in every mol of Mg2Y8(SiO4)(6)O-2, respectively. The critical distances responsible for the cross-relaxation between the D-5(3)-D-5(4) and F-7(6)-F-7(0) transitions of Tb3+ and between the (4)G(5/2)-F-4(9/2) and H-6(5/2)-F-4(9/2) transitions of Sm3+ are estimated to be 1.43 and 1.06 nm, respectively. Both Tb3+ and Dy3+ can be sensitized by Ce3+, but Ce3+ and Sm3+ quench each other.

CHEMICAL-BONDS AND DIELECTRIC-CONSTANTS OF REM (RE=RARE EARTH, M=N, P, AS, SB) CRYSTALS

By using Pillips and van Vechten theory, the chemical bond parameters and dielectric constants of REM (RE=rare earth, M=N, P, As, Sb) crystals were calculated. The values calculated of dielectric constants agree with the experimental values.

Preparation and properties of rare earth hydroxides and oxides ultrafine powders in alcohol

A series of rare earth hydroxides and oxides ultrafine powders have been prepared by precipitation method using alcohol as dispersive and protective reagent. It was first to find that the crystallite size of cubic rare earth oxides had Lanthanide shrinking effect,but average crystal lattice distortion rate possessed lanthanide swelling effect;the change of diffraction intensity with atomic number presented an inverted W type, and double peaks structure was formed.

LUMINESCENCE AND ENERGY MIGRATION IN THE OXYAPATITE CA2GD8(SIO4)6O2 DOPED WITH SEVERAL RARE-EARTH AND MERCURY-LIKE IONS

Energy transfer phenomena have been observed by activating the oxyapatite host-lattice Ca2Gd8(SiO4)6O2 with Eu3+, Tb3+, Dy3+, Sm3+. This is based on the energy migration in the Gd3+ sublattice and trapping by the activators. The trapping efficiency for G

SYNTHESES, CHARACTERIZATION AND CRYSTAL-STRUCTURES OF THE COMPLEXES OF RARE-EARTH WITH O-CHLOROBENZOIC ACID

REL3.H2O (RE=Y, La is similar to Lu; HL = o-chlorobenzoic acid) were synthesized. Their thermal decomposition and IR spectra were studied. The crystal structures of the complexes of neodymium, terbium and lutetium were determined by X-ray diffraction method. They crystallize in the monoclinic space group P2(1)/n and show infinite chain structures. The coordination numbers of rare earth ions are nine.

THE SYNTHESES CHARACTERIZATION AND CRYSTAL-STRUCTURE OF RARE-EARTH COMPLEXES WITH L-PROLIN

The complexes of Ln(L-Pro)s(H2O)2(ClO4)3(Ln = Pr, Nd and Er. L-Pro = L-Proline) were synthesized and characterized by elemental analysis, IR. spectra and thermal analysis. The singal crystal Pr2(L-Pro)6(H2O)4(ClO4)6 Was also obtained. The crystal belongs to monoclinic, P2(1), a = 0.9879 (3) nm, b = 2.1883 (4) nm, c = 1.3393 (2)nm, beta = 91.23(2)-degrees, V = 2.895(1) nm3, Z = 2. R = 0.035 for 5032 observed reflections. The coordination polyhedron of Pr(III) ion comprises six oxygen atoms from L-Pro molecules and two water molecules. Each L-Pro molecule coordinates to two Pr(III) ions through its carboxyl group which serves as a bridging bidentate ligand to form onedimensional chain structure.

SYNTHESES, CHARACTERIZATION AND CRYSTAL-STRUCTURES OF THE COMPLEXES OF RARE-EARTH WITH M-METHYLBENZOIC ACID

REL3(RE=Y, La approximately Lu; HL = m-methylbenzoic acid) were synthesized, and their IR spectra were studied. The crystal structures of the complexes of neodymium and terbium were determined by X-ray diffraction method. Both of them crystallize in the monoclinic space group P2(1)/n and show infinite chain structures. The coordination numbers are nine (Nd3+) and eight (Tb3+), respectively.

SYNTHESES AND CRYSTAL STRUCTURES OF THE COMPLEXES OF RARE EARTH WITH FUMARIC ACID

Six compounds of M2F3 center dot 1.2H(2)O (M=EU, Ga, Tb, Y, Er, LU: H2F=Fumaric acid) have been synthesized. The structures of Eu(III), T b(III), Y(III), Er(III) and Lu(III) compounds have been determined by singal crystal X-ray diffraction method. The complex of Eu(III) crystallizes in tri-clinic space group P (1) over bar, and the coordination number of Eu3+ is ten. The other four complexes crystallize in monclinic space P2(1)/c, and the coordination numbers of the metal ions are eight. Each of the complexes shows a three-dimensional net structures.

STUDY ON RARE EARTH-HEDTA-SERINE TERNARY SYSTEM BY POTENTIOMETRY AND FLUORESCENCE SPECTROSCOPY

In this pare earth-HEDTA-serine (Ser) ternary system has been studied by potentiometric titration at 25 degrees C with an ionic strength of 0.15 mol.L-1 (NaCl). The excitation and fluorescence spectra of TbCl3, Tb-Ser, Tb-HEDTA and Tb-HEDTA-Ser have hem determined at room temperature. The stability constants of these ternary complexes have been obtained, It lieu been found that Tb-HEDTA-Ser ternary system exhibit characteriatic fluorescence spectrum of Tb3+ sensitized by two ligands,The results mean that the chemical hood between the control ion and the ligand in this ternary system is predominantly ionic in character,and the energy transfer from ligand to Tb8+ is performed by a kind of abort-range electron exchange action.

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 ...

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13 degrees N: Evidence from mineralogical and geochemical data

The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103 degrees 54.48'W, lat. 12 degrees 42.30'N, water depth 2655 m) on the East Pacific Rise near lat 13 degrees N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%-1.85%) and Co (65x10(-6)-704x10(-6)) contents, and contain Co+Cu+Zn+Ni > 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13 degrees N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13 degrees N are lower in Sigma REE (5.44x10(-6)-17.01x10(-6)), with a distinct negative Ce anomaly (0.12-0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13 degrees N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13 degrees N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher.