Synthesis and crystal structure of a 1D chainlike rare earth coordinated tungstogermenate： [（CH3）4N]1.50H3.50[Gd（GeW11O39）（H2O）2]·2.5H2O

A 1D zigzag polyoxometalate [(CH3)4N]1.50H3.50[Gd(GeW11O39)(H2O)2]·2.5H2O(1) was synthesized by reaction of the monova-cant polyanion [α-GeW11O39]8- with Gd3+ ions in aqueous solution and characterized by IR, UV spectra, ICP, and X-ray crystallography. X-ray single-crystal structural analysis indicated that the title compound crystallized in a monoclinic lattice, C2/c space group with α=2.8201(5), b=2.2885(3), c=2.4033(4) nm,β=123.875 (2)°, V=12.878(4) nm3, Z=8, R1=0.0623, wR2=0.1287. The solid-state structure of the title compound displayed an infinite one-dimensional arrangement built up of [α-GeW11O39]8- polyanions connected by GdⅢ cations.     

Tetranuclear yttrium and gadolinium 2-acetylcyclopentanoate clusters: Synthesis and their use as spin-coating precursors for metal oxide film formation for field-effect transistor fabrication

Lanthanide clusters [Ln_4(μ_3-OH)_2(η~2-accp)_4((μ-O)-η~2-accp)_6](Ln = Y(4),Gd(5); accp = 2-acetylcyclopentanoate) are accessible by treatment of [M(NO_3)_3·6 H_2 O](M = Y(1),Gd(2)) with 3 equiv. of Haccp(3) in presence of NaOH. The molecular structures of 4 and 5 in the solid-state are discussed. The thermal behavior of 4 and 5 was studied by TG under Ar and O_2, showing multistep decomposition processes. Additionally, DSC studies were carried out under an atmosphere of O_2. PXRD measurements of the TG residues confirm the formation of Ln_2 O_3.Spin-coating experiments were carried out with 4 and 5 for Ln_2 O_3 film deposition on silicon substrates. The layers are smooth, close and are of thicknesses of 18.87±1.13 nm and 25.59 ± 4.55 nm for Ln = Y and Gd, which was evidenced by SEM and EDX studies. Field-effect transistors were successfully fabricated by deposition of carbon nanotubes on top of the Y_2 O_3 films and formation of palladium contacts by a lift-off procedure. An on/off ratio of more than 4 orders of magnitude is achieved without considerable leakage currents. These results demonstrate the potential use of spin-coated Y_2 O_3 as a gate dielectric in electronic devices.     

Self-polymerization and co-polymerization kinetics of gadolinium methacrylate

Gadolinium methacrylate(Gd(MAA)_3) was synthesized by using gadolinium oxide and methacrylic acid as the starting materials and its self-polymerization kinetic was studied based on non-isothermal and isothermal analysis. Moreover, the monomer reactivity ratios of methyl methacrylate(MMA) and Gd(MAA)_3 were evaluated by using Kelen-Tiidos method. The thermal neutron shielding properties of PMMA and poly(MMA-co-Gd(MAA)3) were calculated by MCNP program. The results show that the selfpolymerization of Gd(MAA)3 can be initiated by thermal and free radical and its activation energy is103.35 kJ/mol or 58.55 kJ/mol correspondingly in the solid state or aqueous solution. The polymerization rate,R_p,under low conversion at 65 ℃ is expressed as R_p = K[M]~(1.05)[I]~(0.60). The reactivity ratios of r_1(MMA) and r_2(Gd(MAA)_3) are 0.225 and 1.340, respectively. The ability of thermal neutron shielding of poly(MMA-co-Gd(MAA)_3) is increased by gadolinium contents and is far better than PMMA.     

STUDIES ON RARE EARTH COMPLEXES WITH CROWN ETHERS ⅩⅧ——Synthesis,Characterization and Crystal Structure of[Sc(NO_3)_3(H_2O)_2]·(15-Crown-5)

The single crystal of the complex [Sc(NO_3)_3(H_2O)_2]·(15C5) has been prepared in acetonitrile.Thenew complex has been characterized by elemental analysis,IR spectra,solubility and molar conductancemeasurements.The structure of the complex is determined by single crystal X-ray diffraction analysis.     

Synthesis and thermal behavior of [Li(thf)_3(μ-Cl)La{N(SiMe_3)_2}_3] and its investigation as spin-coating precursor for lanthanum-based layer formation

The lanthanum(Ⅲ) complex [Li(thf)_3(μ-CI)La{N(SiMe_3)_2}_3](3) was obtained by the reaction of LaCl_3 with three equiv of Li[N(SiMe_3)_2]_3 in a tetrahydrofuran solution. The molecular structure of 3 in the solid state was characterized by a tetracoordinated anionic lanthanide(Ⅲ) amide in form of an adduct with LiCl(thf)_3 as evidenced by single crystal X-ray structure analysis. In order to study the suitability of 3 as a precursor for the deposition of La_2O_3/LiLaSiO4 by thin layer deposition techniques,its thermal behavior was investigated by thermogravimetry(TG) and TG-MS-coupled studies. TG studies show a two-step decomposition process, whereby volatile decomposition products can be detected during the second decomposition step. TG measurements under an atmosphere of oxygen produced La_2O_3, Calcination processes of 3 under ambient atmosphere for 10 h at 1000 ℃ gave La_2O_3 and LiLaSiO_4,which was confirmed by PXRD studies. Metal-organic 3 was applied as spin-coating precursor for La_2O_3 thin film formation giving the as-deposited layers nearly crack-free.     

Dehydration,hydrolysis and oxidation of cerium chloride heptahydrate in air atmosphere

The thermal decomposition of CeCl_3·7 H_2 O was studied from room temperature to 800 ℃. Analysis was performed by applying TG-DTA, XRD, FESEM, EDXS, and TG-MS technologies to investigate the thermal decomposition mechanism of CeCl_3·7 H_2 O in air atmosphere. Multiple forms of hydrated cerium chloride compound were observed in the dehydration products. The CeCl_3 hydrolysis product was separated by a continuous centrifugation method and the phase composition was identified as CeO_2,Ce(OH)_3,and CeCl_3·4 H_2 O by XRD analysis. The evolved gas composition was identified as CI_2 and HCI by TG-MS system. Based on the analysis of the experimental results, the mechanism of thermal decomposition of CeCl_3·7 H_2 O was proposed with completion of the dehydration reaction at 224 ℃,the hydrolysis reaction at 170-480 ℃,and the oxidation reaction of CeCl_3 above 480 ℃.     

Kinetic Study on the Induced Coordination Reaction of Lanthanum with p-Acetylcarboxylazo

The absorption spectra of p-ACA(p-acetylcarboxylazo)and its complex with lanthanum ionswere determined.The molar ratio of metal to ligand in the complex was estimated to be 1:2.An inductionperiod was found existing in the coordination reaction between La and p-ACA and the effects oftemperature,acidity and ionic strength on the induction period were studied.The reaction mechanism wasdepicted.The rate equation is consistent with the rate law,R=k[La(H_2O)_6~(3+)][H_3O~+],obtained by kineticmethod.Finally the possible geometric structure of this complex was discussed.     

Energy transfer and 2 μm emission in Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders

(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders doped with various concentrations of Tm~(3+) and Ho~(3+) were prepared by the citrate method. The standard cubic Y_2O_3 phase can be matched in the Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2 O_3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm~(3+) to Ho~(3+) and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to ~3 F_4→~3 H_6 transition of Tm~(3+) and ~5 I_7→~5 I_8 transition of Ho~(3+), respectively.Better spectral properties were achieved in Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm~(3+) and 1 mol% Ho~(3+).     

Synthesis and luminescent properties of terbium complex with 2-amino-4-chlorobenzoic acid

A novel complex [Tb(L)_2(H_2O)_3·H_2O](where L=2-amino-4-chlorobenzoic acid) was synthesized and characterized by a series of analysis. The molecular formula of complex was confirmed by Fourier transform infrared(FT-IR) spectroscopy and thermogravimetric/differential thermogravimetric(TG-DTG) measurements. The optical properties of complex was measured by ultraviolet spectroscopy(UV) and fluorescence spectroscopy(FS). The results indicated that Tb~(3+) in the complex was coordinated by ligand, and the complex emitted bright yellow-green luminescence with main peak at 548.8 nm with excitation at 369.4 nm.     

[Y(dbm)_3(H_2O)]:Synthesis,thermal behavior and spin-coating precursor for Y_2O_3 layer formation

The synthesis,structure and thermal behavior of [Y(dbm)_3(H_2 O)](3)(dbm = 1,3-diphenyl-1,3-propandionate) and its use as a spin-coating precursor for Y_2 O_3 deposition is reported. Complex 3 was prepared by the reaction of [Y(NO_3)_3·6 H_2 O](1) with 3 equiv of Hdbm(2) in presence of NaOH. The molecular structure of 3 in the solid-state was determined by single X-ray crystal diffraction. Both C_1 symmetric crystallographically independent species of 3 possess a YO7 coordination setup with minor deviation from an ideal capped octahedron coordination geometry(∧ enantiomer). Complex 3 forms a1 D chain, due to intermolecular hydrogen bonds between the coordinated H_2 O molecule and the 0 atom of the dbm ligand, respectively. The thermal decomposition behavior of 3 was investigated by thermogravimetric studies in the temperature range of 40-800 ℃ and 40-1300 ℃ under an oxygen and argon atmosphere, respectively. Powder X-ray diffraction(PXRD) measurements of the residues confirmed the formation of Y_2 O_3. Complex 3 was applied as a spin-coating precursor for yttrium oxide film formation on either Si wafers with a continuous 100 nm thick SiO_2 film, or with a native oxide layer.The as-deposited Y_2 O_3 layers are smooth, conformal, dense and transparent and are of a thickness of 27 and 30 nm, respectively.     

INFLUENCE OF Pr_6O_(11) ON THE GAS SENSING CHARACTERISTICS OF SnO_2 SEMICONDUCTOR

This paper is to discuss the sensing characteristics of SnO_2 semiconductor components in whichPr_6O_(11) is added.When experimenting under 11 gases of CH_3COCH_3,C_2H_5OH.C_6H_5CH_3,H_2,NH_3,CO,CO_2 CH_4,C_4H_10,n—C_6H_(14)and n—C_7H_(16),we find that the components have selectivity to CH_3COCH_3,C_2H_5OH and that the ideal amount of Pr_6O_(11) in the components is about I.Owt%.The experiments also showthat with the increase of the amount of Pr_6O_(11),the ideal working temperature,the response and restorationtime decrease.     

IN-SITU HVEM STUDY ON PHASE TRANSITION OF YBa_2Cu_3O_(7-x) SUPERCONDUCTING COMPOUND IN PROCESS OF HEATING

In-situ HVEM observation on phase transition of the YBa_2Cu_3O_(7-x) superconducting compound in pro-cess of heating was carried out,and high temperature X-ray diffraction analysis in air and X-ray diffractionphase analysis for the sample treated in vacuum condition were made.The results showed that the temperatureof phase transition is related to oxygen content in the sample and in general,is 100℃ to 120℃ lower in vacu-um condition than in air.At 320℃ to 350℃ twin bands begin to disappear,and some Cu_2O are formed on thesurface of the sample and transit from orthorhombic YBa_2Cu_3O_(7-x) to arthorhombic Y_2BaCuO_5 compound.This transition was completed at about 500℃.Above 900℃,this compound consists of the Y_2BaCuO_5,BaCuO_2,Y_2O_3 and some other minor compounds.No phase transition was observed during cooling thesample.     

Substituent effects on novel lanthanide(Ⅲ) hydrazides complexes

New lanthanide(Eu~(3+) and Gd~(3+)) complexes were successfully synthesized and the effect of the p-phe nyl substituent on the Eu~(3+)luminescent properties was evaluated.In this sense,benzhydrazide,p-toluic hydrazide,4-hydroxybenzhydrazide and 4-aminobenzoic hydrazide were used as ligands and the complexes were obtained by mixing the lanthanide salts with hydrazides in ethanol at room temperature and keeping the reaction for 2 h under mechanical stirring.Crystal of Gd-amino was obtained and its structure was elucidated by single-crystal X-ray diffraction,revealing that Gd~(3+)centered in a distorted tricapped trigonal-prismatic molecular geometry.IR spectroscopy and the elucidated structure confirm hydrazides acting as bidentate ligands binding to Ln~(3+)ions through the oxygen of carbonyl group and the nitrogen of terminal amine,forming a five-membered ring,CHN analyses confirm the molecular formulas [Gd(amino)4(H_2 O)](NO_3)_3·(C_2 H_5 OH) and [Eu(toluic)3(H_2 O)_3](NO_3)_3.Lower T_1 state energies are observed for ligands p-substituted with higher electron donating capacity groups,such as p-NH_2 and pOH.In contrast,higher lifetimes and quantum efficiencies are obtained for Eu~(3+)complexes with ligands p-H and p-CH_3 substituted,which are not deactivator groups.     

A hydrometallurgical method of energy saving type for separation of rare earth elements from rare earth polishing powder wastes with middle fraction of ceria

This study described a hydrometallurgical method to investigate the separation of rare earth elements(REEs)from rare earth polishing powder wastes(REPPWs)containing large amounts of rare earth oxides with a major phase of CeO_2 and minor phases of La_2O_3,Pr_2O_3,and Nd_2O_3 using a process devised by the authors.The suggested approach consisted of five processes:the synthesis of NaR E(SO_4)_2·xH_2O from rare earth oxides in Na_2SO_4-H_2SO_4-H_2 O solutions(Process 1),the conversion of NaR E(SO_4)_2·xH_2O into RE(OH)_3 using NaO H(Process 2),and the oxidation of Ce(OH)_3 into Ce(OH)_4 using air with O_2 injection(Process 3),followed by Processes 4 and 5 for separation of REEs by acid leaching using HCl and H_2SO_4,respectively.To confirm the high yield of NaR E(SO_4)_2·xH_2O in Process 1,experiments were carried out under various Na_2SO_4 concentrations(0.4–2.5 mol/L),sulfuric acid concentrations(6–14 mol/L),and reaction temperatures(95–125 oC).In addition,the effect of the pH value on the separation of Ce(OH)_4 in HCl-H_2 O solutions with Ce(OH)_4,La-,Pr-,and Nd(OH)_3 in Process 4 was also investigated.On the basis of above results,the possibility of effective separation of REEs from REPPWs could be confirmed.     

Metal-organic frameworks of lanthanide iminodiacetates and tartrates:Synthesis,structural characterization and luminescence properties——Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Two series of lanthanide-containing metal-organic frameworks(Ln-MOFs) of the general formula{[Ln(HIDA)_2 H_2 O]ClO_4·H_2 O}_n(Ln = La(1),Nd(2),Eu(3),Gd(4),Tb(5),Eu:Tb(6);H_2 IDA=iminodiacetic acid) and [Ln(TT)(HTT)(H_2 O)_3]_n(Ln=Eu(7),Gd(8),Tb(9),Dy(10),and Eu:Tb(11);H_2 TT=tartaric acid)were synthesized by reacting Ln(ClO_4)_3 with iminodiacetic acid and L-tartaric acid,respectively.All compounds were structurally characterized by single-crystal X-ray diffraction.Elemental analyses are co nsistent with the corre sponding crystallographically generated formulas.Mo reover,the luminescence properties of both the single and mixed-lanthanide complexes were studied.Near infrared,red,and green emissions that are characteristic of Nd(Ⅲ),Eu(Ⅲ),and Tb(Ⅲ) are observed for 2,3/7,and 5/9,respectively.For the two mixed-lanthanide complex systems 6 and 11,depending on the relative amount of Eu(Ⅲ) and Tb(Ⅲ),the color of emission can be fine-tuned.It is found that a small amount of Eu(Ⅲ) is adequate for the observation of the most intense transition of Eu(Ⅲ).This is believed to be a result of energy transfer from Tb(Ⅲ) to Eu(Ⅲ) within the same complex-a conclusion supported by the significantly shortened lifetime of Tb(Ⅲ) and the accompanying enhanced lifetime of Eu(Ⅲ) in the mixedlanthanide complex with respect to the corresponding values for the pure Tb(Ⅲ) and Eu(Ⅲ) complexes with the same ligand.     

Synthesis,photoluminescence properties and thermal investigation by TG-MS of RE(DAS)_3·xH_2O(RE=Eu~(3+),Tb~(3+))

Rare earth(Ⅲ) diphenyl-4-amine sulfonates(RE(DAS)_3·xH_2O,RE=Eu~(3+),Tb~(3+))phosphors were synthesized by precursor method from barium diphenyl-4-amine sulfonate and rare earth sulfates.FTIR,TG/DSC coupled to mass spectrometry(TG/DSC/MS),X-ray powder diffraction(XPD),scanning electron microscopy(SEM) and photo luminesce nce(PL) spectroscopy were utilized to structurally and morphologically characterize the samples.Thermal decomposition of Eu(DAS)_3·7H_2O and Tb(DAS)_3·2H_2O at 973 K under dynamic air atmosphere results in crystalline Eu_2O_2SO_4 and Tb_2O_2SO_4 materials,respectively.Accordingly,MS spectra reveal the liberation of thermal decomposition products of precursors,largely as CO_2,NO_2 and SO_2 gases.The diphenyl-4-amine sulfonate(DAS) ligand demonstrats a good stabilizing property for Eu~(3+) and Tb~(3+) ions.The Eu(DAS)_3·7H_2O and Tb(DAS)_3·2H_2O compounds display efficient red and green emissions,under UV excitation,arising from the ~5D_0→~7F_J(J=0-4) and ~5D_4→~7F_J(J=0-6) transitions of the Eu~(3+) and Tb~(3+) ions,respectively.     

Synthesis and characterization of monodisperse Eu~(3+) doped gadolinium oxysulfide nanocrystals

Gd_2O_2S:Eu~(3+) nanoparticles were synthesized using two step process consisting of sulfuration of basic carbonates obtained by homogenous precipitation.Annealing of lanthanide nitrates at total concentration of 5×10~(-3) mol/L in a water solution containing relatively high,three molar concentration of urea ensured the optimal conditions for the reproducible preparation of uniform and small spherical particles.During sulfuration step elemental sulfur was mixed with precursor which eliminated necessity of using an auxiliary furnace and provided sulfur-reach reaction atmosphere.Such optimized protocol afforded synthesis of spherical and non-agglomerated nanoparticles with diameter smaller than 100 nm.The precursors morphology was maintained,but particles size was reduced by 15%-20%during sulfuration.The results indicated that higher emission intensity was observed for Gd_2O_2S:Eu~(3+)(8%)oxysulfide sample synthesized using crystalline Gd(CO_3)OH precursor,than for that obtained from amorphous Gd_2(OH)_2(CO_3)_2·H_2O precursor,although some further efforts to improve morphology of the former are still required.     

杂多配合物的催化性能研究 (Ⅰ)K_(19)[Ln(α_2—P_2MO_(16)VO_(61))_2]·nH_2O型杂多酸盐的合成与表征

本文首次报道通式为K_(19)〔Ln(α_2—P_2Mo_(16)VO_(61))_2〕·nH_2O的四元杂多酸盐的合成条件、结构及基本物理化学性质研究的有关内容。用元素分析、电导测定及离子交换实验、红外、紫外及热分析鉴定了这些配合物,从而推测配体P_2Mo_(16)VO_(61)-为α_2—型Dawson结构,当配体与稀土离子Ln~(3+)形成配合物后,Ln~(3+)与配体空穴外沿的桥氧进行配位,形成配位数为8、结构与K_(16)[Cc(IV)(α_2—P_2W_(17)O_(61))_2]·50H_2O相似的四方反棱柱型配合物。     

Construction of NIR luminescent nanoscale lanthanide complexes with new flexible Schiff base ligands

Four mono-and bi-nuclear lanthanide complexes [LnL~1(No_3)(H_2O)DMF](Ln=Nd(1) and Yb(2)) and[Ln_2(L~2)_2(OAc)_2](Ln=Nd(3) and Yb(4)) were synthesized by using two new Schiff base ligands with long(CH_2)_2 NH(CH_2)_2 backbone.The lengths of the Schiff base ligands are about 1.8 nm.The bi-nuclear lanthanide complexes 3 and 4 have nanoscale structures with sizes of approximately 0.7 nm×1.1 nm×1.6 nm.For 3,the molar ratio of Nd:Br:O obtained by the energy dispersive X-ray spectroscopy analysis is in agreement with the crystal structure.The chromogenic Schiff base ligands in1-4 can efficiently transfer energy to lanthanide ions,thus,these complexes exhibit the typical NIR luminescence of lanthanide ions.Interestingly,3 and 4 have higher NIR emission quantum yields(Φ_(em))than 1 and 2,respectively.     

Synthesis and characterization of aminophenolate-ligated rare-earth metal amide complexes and their catalytic activity for lactides polymerization

Amine elimination of Ln[N(SiMe_3)_2]_3(μ-Cl)Li(THF)_3 with aminophenol H[ON] {H[ON]=2-(CH_2 NC_5 H_(10))-4,6-~tBu_2-C_6 H_3OH} in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]_2 LnN(SiMe_3)_2(Ln=Yb(1),Y(2),Gd(3),Sm(4),Nd(5)) in 57%-73% isolated yields.All these complexes were characterized by elemental analysis.The molecular structures of complexes 1-4 were determined by single crystal X-ray diffraction.These complexes are highly active for L-Iactide polymerization to give high molecular weight polymers with unimodal molecular weight distributions.In addition,these complexes can also initiate rac-lactide polymerization with high activity to afford heterotactic-rich polylactides.