Synthesis and luminescence properties of ternary europium complexes in titania matrix in the presence of dimethylformamide by a sol-gel process

In-situ synthesis of ternary europium complex with thenoyltrifluoacetone (TTA) and 1,10-phenanthroline (phen) in titania matrix in the presence of dimethylformamide (DMF) by a sol-gel process was described, which was confirmed by the luminescence excitation spectra and infrared spectra. The titania gel that contains europium complex exhibits Eu3+ characteristic emission bands and presents a longer fluorescence lifetime than the pure complexes dissolved in ethanol solution. The concentration effect on the luminescence intensity was also investigated.

Separation of Th4+ and RE3+ with hollow fiber extraction

Separation of Th4+ and RE3+ was investigated by hollow fiber membrane extraction with N1923 in countercurrent recirculating operation. The effect of Hf concentration in aqueous phase and flow rates of aqueous and organic phases on mass transfer coefficient was tested. Then the extraction of Th4+ from RE sulfate obtained from Baotou ore was carried out. The results obtained show that the mass transfer coefficient of Th4+ changes with the flow rate of aqueous phase, but does not change with the flow rate of organic phase and H+ concentration in aqueous phase, which suggests that the mass transfer rate of Th4+ is controlled bg that in the water critical layer, The mass transfer rate of RE3+ does not change with the flow rate of water phase, changes a little with the flow rate of organic phase, and changes with H+ concentration, which suggests that the mass transfer rate is controlled by their reaction rate with N1923. Th4+ could be extracted completely in 8 h from RE sulfate solution of Baotou ore with relatively less extraction of RE3+. So the separation of radioactive element under the sealed condition could be done.

Vibrational spectrum and luminescence properties of CaAl2B2O7 : Eu3+

The vibrational spectrum of the CaAl2B2O7 was investigated. It was shown that the vibrations of the BO3 groups are present in the region of 1400 similar to 600 cm(-1), and the bands at 519 nm(-1) may originate from the AlO6 vibration. The luminescence properties of Eu3+ in CaAl2B2O7 were investigated. It was found that the Eu3+ ion in CaAl2B2O7 occupies two different sites. Investigation on the phonon sideband of Eu3+ indicates that BO3 groups are present in the:surroundings of Eu3+ ions.

Study of physicochemical properties and active oxygen in structures of layered mixed La4BaCu5-xMxO13+lambda (M = Mn, Co)

Two series of layered mixed oxides La4BaCu5-xMxO13+lambda(M = Mn, Co, x = 0 similar to 5) were prepared and characterized by means of XRD, XPS, O-2-TPD and chemical analysis. The results show that their structures are 5-layered ABO(3) perovskite, and the XPS and O-2-TPD investigation confirms that there exists synergistic effect between Cu ion and M when M ion is doped into the lattice of La4BaCu5O13+lambda,, and the synergistic effect between Mn and Cu is stronger than that of Cu-Co.

pH-potentiometric study on rare earths and calcium binary and ternary complexes with DL-malic acid and L-hydroxyproline

The stability constants of M-L binary system and M-L-L' (M = La3+ similar to Yb3+, Y3+ and Ca2+; L= DL-malic aicd, L' = L-hydroxyproline) ternary system were determined by pH-(0)-tentiometric method under the simulating physiological condition(37 degrees C, I=0.15 mol/L NaCl). The complex species MpLqLr'H-s(abbr as pqrs) in the sytems were ascertained by program COMPLEX. The results show that there are three species(1101, 1100 and 1200) in M-L binary system and one species(1010) in M-L' binary system. In addition to the above four species, a new species, 1112 was found in the M-L-L' ternary system, which is the only species of mixed ligands. Rare earth ions form more stable complexes than calcium ion does and the stability differences between their complexes in the ternary system are less than that in the binary system. The distributions of all the species in La-L-L' ternary system vs pH are discussed.

Physico-chemical properties and catalytic behavior of LnSrNiO(4) mixed oxides for NO decomposition

A series of LnSrNiO(4)(A(2)BO(4), Ln = La, Pr, Nd, Sm, Gd) mixed oxides with K2NiF4 structure, in which A-site(Sr) was partly substituted by individual light rare earth element, was prepared. The solid state physico-chemical properties including crystal structure, defect structure, IR spectrum, valence state of H-site ion, nonstoichiometric oxygen, oxygenous species, the properties of oxidation and reduction etc. as well as the catalytic behavior for NO decomposition on these mixed oxides were investigated. The results show that all of these mixed oxide catalysts have high activity for the direct decomposition of NO(at 900 degrees C the conversion of NO is more than 90%). The effect of the substitution of light rare earth elements at A-site on catalytic behavior for NO decomposition was elucidated.

Synthesis, luminescence and magnetic properties of YGa3-xCrxB4O12

The synthesis temperature of YGa3B4O12 and the effect of the synthesis temperature and chromium doping on the luminescence properties were studied. YGa3-xCrxB4O12 were synthesized and their magnetic properties were described. Results show that the fluorescence intensity increases with the increasing of synthesis temperature. The structure of compounds was stabilized, and their emission spectra were changed when small quantity of chromium was doped in. The magnetic susceptibilities increase with the increasing of Cr3+ concentration.

Electrochemical behavior of Nd3+ and Ho3+ in LiCl-KCl eutectic melt

The electrochemical behavior of Nd3+ and Ho3+ ions on molybdenum electrode in the LiCl-KCl eutectic melts has been studied by cyclic voltammetry and open-circuit potentiometry. The results show that the reduction process of Nd3+ and Ho3+ ions on molybdenum electrode is one-step three electron reversible reaction. The diffusion coefficients of Nd3+ and Ho3+ ions are 1.13 x 10(-6) cm(2).s(-1)(450 degrees C) and 2.142 x 10(-5) cm(2).s(-1)(450 degrees C), respectively. The measured standard electrode potential of Ho3+/Ho is 2.987 V(vs. Cl/Cl-), being more negative than the theoretical one, the reason of which is also discussed.

Luminescence properties of Ce3+ in KMF3(M=Mg, Ca, Sr, Ba) hosts with perovskite structure

KMF3(M = Mg, Ca, Sr, Ba) compounds were synthesized by solid state reaction under argon atmosphere. Their structures were determined by X-ray diffraction. It belongs to cubic system with perovskite structure. The excitation and emission spectra of KMF3:Ce3+ were measured. According to the characteristics of spectral structures, the occupation site of Ce3+ is discussed.

Two-step-method extraction of endohedral metallofullerenes

A new and efficient extraction method of endohedral metallofullerenes, especially of rare-earth elements encapsulated metallofullerenes, has been reported in this paper. Soxhlet-extraction of raw soot with toluene was used in the first step to wash away most accompanying C-60, C-70. Then pyridine was chosen as solvent to obtain high-temperature and high pressure extract. Two kinds of extract were analysed by DEI-MS and LDI-MS, the results indicate that this two-step method can provide the extract which has the highest fraction of endohedral metallofullerenes. So it will greatly simplify the following separation and purification processes of metallofullerenes.

Roles of oxygen vacancy and lower valence metallic ion in direct decomposition of NO over La-2-x(Sr,Th)(x)CuO4+/-lambda

Two systems of La2-xSrxCuO4+/-lambda and La2-xThxCuO4+/-lambda, mixed oxides with K2NiF4 structure were synthesized. The compositions and structures of the catalysts were characterized by means of XRD, XPS, chemical analysis and so on. The catalytic behavior for the direct decomposition of NO has been investigated. The results show that the catalytic activity is closely related to the oxygen vacancy and lower valence metallic ion in the direct decomposition of NO. The presence of oxygen vacancy is necessary for mixed oxide to have steady activity in NO decomposition.

Relationship between the dissolution behaviours and current efficiencies of La, Ce, Pr and Nd in their chloride molten salts

The dissolution behaviours of La and Nd in their chloride molten salts were studied by means of the see-through cell, electrochemical weak polarization and quantum chemistry (extended Huckel molecular orbital). The reasons for the low current efficiencies of rare earth metals and the difference between La and Nd in their own chloride electrolytes on the basis of the solubility, rate of dissolution, and existing state of the metals dissolved as well as the structure of the melts, are discussed.

INTERACTION OF LANTHANUM AND CALCIUM WITH HUMAN ERYTHROCYTE-MEMBRANES

The effect of lanthanum and calcium on the structure and function of human erythrocyte membranes was investigated by fluorescence polarization, spin- labeled electron spin resonance (ESR) and laser Raman spectroscopy. The results showed that low concentration of La3+ (0.5 mu mol/L) activated a Little (Na++K+)-ATPase and Mg2+-ATPase activities, and it inhibited obvi ously the ATPase activities with increasing its concentrations. La3+ lowered the lipid fluidity of human erythrocyte membranes and decreased the vibration intensity of alpha-helix of the protein in the Amide I '. The effect of Ca2+ on the lipid fluidity and alpha-helix of the protein in the Amide I ' was smaller than that of La3+.

POLYMERIZATION OF ACRYLONITRILE INITIATED BY DI(2,6-DI-TERT-BUTYL-4-METHYLPHENOXO) SAMARIUM COMPLEX

The polymerization of acrylonitrile initiated by organolanthanide complexes alone is studied for the first time. The effect df polymerization conditions on catalytic activity of the title complex and molecular weight of the polymers produced have been studied.

EFFECTS OF METAL-IONS ON THE CONFORMATION OF POLAR HEADGROUP OF SPHINGOMYELIN BILAYER

With the wide application of rare earth in agriculture, medicament, especially the application of Gd-DTPA as nuclear magnetic resonance image reagent in clinical practice([1]), the studies on the toxicology in biological body, as well as the study on the use as informative probes instead of divalent calcium ion in biological and biochemical research have attracted intensive concern([2]). Phospholipids bilayers have served as a model of biomembrane in the last two decades. The effects of metal ions on the conformation of polar headgroup of dipalmitoylphosphatidylcholine (DPPC) bilayers have been reported([3]). Sphingomyelin is major component of several biological tissues such as brain and nerve cells and has identical polar headgroup to DPPC. The interaction of metal ions with sphingomyelin bilayer remains nonrevealed. This note presents the results of the study on this aspect.