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.

THERMAL-DECOMPOSITION PROCESS OF SOME RARE-EARTH NITRILOTRIACETIC ACID SERINE MIXED COMPLEXES

Thermal decomposition processes of the mixed complexes of nitrilotriacetates of Pr, Sm, Tb, Ho and Tm with 2-amino-3-hydroxypropionic acid have been investigated. The results indicate that serine may coordinate to the rare earth ion via its hydroxyl group, not by means of its carboxyl group. From the thermogravimetric and the derivative thermogravimetric curves it can be deduced that there may be six or seven steps in the thermal decomposition process of these mixed complexes, and that not all thermal decomposition processes in these mixed complexes are the same. Some possible thermal decomposition reactions have been proposed, and the differences between the thermal decomposition processes of these complexes are also discussed.

A NEW HYDROGEN SENSOR WITH RARE-EARTH COMPLEX FLUORIDE

A new type of solid-state galvanic cell for detecting a small amount of hydrogen in air at room temperature is proposed. The sensor cell is a potentiometric cell using Ce0.95Ca0.05F2.95 as solid-state electrolyte. The cell exhibits good sensing properties to hydrogen in air at room temperature.

STUDY ON COMPLEXES OF RARE-EARTH WITH L-PHENYLALANINE BY POTENTIOMETRY WITH CALORIMETRY

The stability constants and thermodynamic functions for complexes of rare earth with L-phenylalanine have been determined by potentiometry and calorimetry at 25-degrees-C and ionic strength of 0.15mol.dm-3(NaCl). Stability of the complexes shows the "Tetrad effect". The entropy change makes a predominant contribution to the stability of these complexes. The ligand is coordinated to rare earth ions through its -CO2- and -NH2 group, and dehydration of ions plays an important role in coordination reaction.

INVESTIGATION OF THE PHOTOELECTRONIC PROPERTIES OF RARE-EARTH MONOPHOSPHIDES

The optical, electrical and photoelectronic properties of rare earth monophosphides (LnP, Ln = La, Nd, Sm and Y) have been studied. The experimental results indicate that their resistivities are low, the electric conduction in all of them is N-type, the energy gaps of LaP, NdP, SmP and YP are 1.46eV, 1.15eV, 1.1eV and 1.0eV, respectively. The SmP/Si and YP/Si junctions exhibit the photovoltaic effect. They may be used as photoelectronic sensors.

THE PHOTOELECTRIC PROPERTIES OF THIN-FILMS OF RARE-EARTH MONOPHOSPHIDES

The optical, electrical and photoelectric properties of rare earth monophosphides (LnP, Ln = La, Nd, Sm, Y, Dy and Yb) have been studied in thin films. The films exhibit semiconducting behaviour with energy gaps of 1.0-1.46 eV and n-type electrical conduction. Their resistivities are 10(-2) OMEGA-cm with corresponding Hall mobilities of 8.5-400 cm2 V-1 s-1. The films are deposited on a p-type silicon substrate in vacuum. Voltage-current characteristic measurements show that a p-n junction has been formed between LnP and silicon. Spectral sensitivity and a photovoltaic effect have been observed in LnP-Si junctions. They may be useful photoelectric materials.

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.

XPS STUDY ON RARE-EARTH PHTHALOCYANINE COMPLEXES

The rare earth monophthalocyanine complexes, LnPcCl and LnPc(OAc)2 (Ln = Tb, Ho, Tm, Lu, Pc=Phthalocyanine, OAc = Acetate), were synthesized. The electronic structures of the complexes have been studied by means of XPS. The experimental results of binding energies for the complexes indicate that the bonds of the complexes have a certain covalent character depending on L-->Ln charge transfer. This L-->Ln charge transfer process of phythalocyanine complexes differs from that of crown ether complexes. Both coordination and substitution are included in the former case, but only coordination in the latter. Phthalocyanine ring is an electrophilic group and its electronegativity is large. So, the O1s binding energies of coordinating oxygen atoms of acetate in LnPc(OAc)2 are larger than those of Ln(OAc)3. The magnitude of valent charge delocalized from ligand onto metal atom is dependent on electronegativity, coordination number, valence state and so on. Because coordination number of Ln in LnPc(OAc)2 is larger than that in LnPcCl and electronegativity of Clin LnPcCl is larger than that of O in LnPc(OAc)2, the Ln4d5/2 binding energies of LnPc (OAc)2 are less than those of LnPcCl.

DIELS-ALDER REACTION CATALYZED BY RARE-EARTH CHLORIDES

Rare earth chlorides were used to catalyze the synthesis of 2-butoxy-3, 4-dihydro-2H-pyran using equimolar acrolein and vinyl butyl either. The cycloadduct is unstable which undergoes catalytic ring opening oligomerization. The way to stabilize the cyclo adduct has been studied, thus high yields of 90-95% were obtained.

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.