Synthesis, structure and spectroscopic studies of europium complex with S（＋）-mandelic acid

The Eu3+ complexes with S(+) -mandelic acid were synthesized in the form of powders by mixing aqueous solutions of EuCl3,S(+) -mandelic acid and NaOH in different molar ratios.The powders were characterized by elemental analysis,X-ray powder diffraction(XRPD) method,Fourier transform infrared(FTIR) and Raman spectroscopy,UV-vis reflectance and luminescence spectra as well as lumi-nescence lifetime measurements.It was found that all studied powders of Eu3+ complexes with S(+) -mandelic acid were isostructural and crystalline and formed compounds with the formula Eu(Man) 3(H2O) 2.     

Polymerization of ε-caprolactone by lanthanide trisborohydrides and crystal structure of [Ce（BH4）2（THF）5] [Ce（BH4）4（THF）2]

Complexes of lanthanide trisborohydrides, formally Ln(BH4)3(THF)n (Ln=La, Ce, Sm, Yb), were synthesized and their catalytic activity for polymerization of ε-caprolactone was studied. All the complexes can catalyze this polymerization. It was found that the catalytic activities decreased in the order of La>Ce>Sm>Yb. The crystal structure of cerium trisborohydride was determined for the first time by single crystal X-ray diffraction analysis. It is an ionic pair complex of [Ce(BH4)2(THF)5][Ce(BH4)4(THF)2]. The cationic part involves two η3-BH4 ligands, while the anionic part involves two η3-BH4 groups and two η2-BH4 groups.     

Hydrothermal syntheses and characterization of three lanthanide coordination complexes constructed by 2,2’:6’,2’’-terpyridine and 2,2’-biphenyldicarboxylic acid

Two 1D coordination polymers [Ln2(dpdc)3(tpy)2·H2O]n [Ln=Nd 1, Yb 2, H2dpdc=2,2’-biphenyldicarboxylic acid and tpy= 2,2’:6’,2’’-terpyridine] and one dinuclear complex Er2(dpdc)2(Hdpdc)2(tpy)2 3 were obtained via hydrothermal reactions and determined by X-ray diffraction analysis. The crystal structure data of 1 and 2 revealed that two coordination polymers were isostructural and possessed a 1D chain framework consisting of eight-coordinated Ln(III) centers. In the asymmetric unit, the two Er(III) ions in 3 were both nine-coordinated and had similar coordination environments. The Er(III) ions were bridged by dpdc2-ligands into dinuclear structures. The complexes were also characterized by IR spectra and thermogravimetric analysis. The solid fluorescence of 1 and 3 was also investigated at room temperature.     

Spectroscopic properties of ytterbium doped KLu（WO_4）_2

Monoclinic Yb3+-doped KLu(WO4)2 (Yb:KLuW) crystal with large sizes was grown by top-seeded solution growth (TSSG) method. Room-temperature absorption and fluorescence spectra were measured. The ground-state energy-level splitting was 562 cm-1. The absorption cross section, peak emission cross section as well as the minimum inversion fraction ?min and the minimum absorbed pump intensity Imin were calculated. The measured emission lifetime was 0.676 ms and the emission spectral bandwidth (FWHM) was up to 55 nm. In comparison with established laser crystals the results suggested that this crystal has potential application in efficient tunable and femtosecond laser operation.     

Photoluminescence properties and effect of Bi~（3＋） dopant of Eu~（3＋） and Dy~（3＋） co-doped Sr_3V_2O_8

Photoluminescence properties of Sr 2.5 Dy 1/3-x Eu x V 2 O 8(x=0,0.06,0.12,0.18,0.24,0.33) were investigated.The excitation spectra included a broad band in the short wavelength region and several sharp lines in the longer wavelength region,and the spectral origin were discussed.The emission spectra were measured in two different exciting ways,i.e.,exciting the VO 4 group at 270 nm and the Eu 3+ ion at 398 nm,respectively,and the energy transferring process was reasonably suggested.Furthermore,multi-color emission could be achieved in Sr 2.5 Dy 1/3-x Eu x V 2 O 8,indicating that the studied samples had potential applications in the white light emitting diodes.Further investigation showed that reducing the concentration of Eu 3+ and Dy 3+ and introducing Bi 3+ as a sensitizer ion greatly enhanced the emission intensity.     

Synthesis and luminescence properties of Sr3-z（AlxSi1-x）O5-xFx：zCe^3＋phosphors

Sr3-z(Alx,Si1-x)O -5-xFx:zCe3+ phosphors were synthesized by high-temperature solid-state reaction.The structure and luminescence properties of phosphors with various Al/Si ratios and Ce3+ concentrations were characterized using various methods such as X-ray diffraction,photoluminescence excitation and photoluminescence spectra.XRD result displayed that a complete solid solution between Sr3AlO4F and Sr3SiO5 was formed.With the increasing of x value,a broader excitation band and stronger absorption appeared in the blue light region.Moreover,the emission band shifted to a shorter wavelength and the emission intensity reached a maximum at x=0.6.By adjusting the concentration of Ce3+,a widely tunable range of emission wavelength under the excitation of 460 nm was obtained from the green to yellow regions.In addition,the concentration and thermal quenching were also discussed.     

Studies on electrical properties and CO-sensing characteristics of La_（0.9） _（0.1）FeO_3

Semiconducting sensors offer an inexpensive and simple method for monitoring gases. Sensors based on the ABO3-type composite oxides materials have an advantage of high stability. The perovskite structures of these compounds are preserved, when an A-site deficiency of some perovskite structure compounds was formed. However, they exhibit particular physical properties. In this paper, La0.9 0.1FeO3 powder with an orthorhombic perovskite phase was prepared by sol-gel method. The electrical properties and CO-sensing characteristics of the La0.9 0.1FeO3 were also investigated. The results demonstrated that the La0.9 0.1FeO3 was a p-type semiconductor material. Compared with LaFeO3, the conductance of La0.9 0.1FeO3 was better than that of LaFeO3. The sensor based on La0.9 0.1FeO3 showed excellent CO gas-sensing characteristics.     

Luminescent properties of Eu~（3＋） doped Gd_2WO_6 and Gd_2（WO_4）_3 nanophosphors prepared via co-precipitation method

Eu3+ doped Gd2WO6 and Gd2(WO4)3 nanophosphors with different concentrations were prepared via a co-precipitation method. The structure and morphology of the nanocrystal samples were characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The emission spectra and excitation spectra of samples were measured. J-O parameters and quantum efficiencies of Eu3+ 5D0 energy level were calculated, and the concentration quenching of Eu3+ luminescence in different matrixes were studied. The results indicated that effective Eu3+:5D0-7F2 red luminescence could be achieved while excited by 395 nm near-UV light and 465 nm blue light in Gd2WO6 host, which was similar to the familiar Gd2(WO4)3:Eu. Therefore, the Gd2WO6:Eu red phosphors might have a potential application for white LED.     

Sintering effect on ageing behavior of rare earths （Pr6O11-Er2O3-Y2O3 ）-doped ZnO varistor ceramics

The electrical properties and ageing behavior of the rare earths (Pr6O11-Er2O3-Y2O3)-doped ZnO varistor ceramics were systematically investigated at sintering temperature range of 1335-1350°C. With an increase in the sintering temperature, the sintered density increased from 5.41 to 5.64g/cm3 and the average grain size increased from 5.8 to 7.9μm. The varistor properties and ageing behavior were significantly affected by small sintering temperature range of 1335-1350°C. The breakdown field noticeably decreased from 5767 to 3628V/cm with an increase in the sintering temperature. The varistor ceramics exhibited the highest nonlinear coefficient (43.2) at the sintering temperature of 1340°C. The varistor ceramics sintered at 1350°C exhibited a surprisingly excellent stability by exhibiting 0.3% in the variation rate of the breakdown field and 0.3% in the variation rate of the nonlinear coefficient for ageing stress of 0.95 E1mA/150°C/24 h.     

Investigation of the crystal structure and magnetic properties of Nd_（3-x）GdxCo_（11）B_4 borides

Polycrystalline samples of pseudo-ternary intermetallic Nd3-xGdxCo11B4 (x=0,1,2,3) borides prepared by standard arc-melting were characterized by X-ray powder diffraction (XRPD),magnetization and differential scanning calorimetry (DSC) measurements. The X-ray diffraction patterns indicated the hexagonal Ce3Co11B4-type structure with P6/mmm space group for each composition. The substitution of Gd for Nd led to a decrease of the unit-cell parameters a and the unit-cell volume V,while the unit-cell parameter c increased linearly. Magnetic measurements indicated that all samples were ordered magnetically below the Curie temperature. The Curie temperatures increased as Nd was substituted by Gd. The saturation magnetization at 4 K decreased upon the Gd substitution up to x=1,and then increased.     

Synthesis, Characterization and Thermal Decomposition of Ln (Me2dtc)3(phen) (Ln=La, Pr, Nd, Sm)

Four solid complexes of Ln(Me2dtc)3(phen) (Ln=La, Pr, Nd, Sm) were synthesized in anhydrous ethanol by the reaction of lanthanide chloride low hydrate with the mixed ligand of sodium dimethyldithiocarbamate and 1, 10-phenanthroline·H2O (phen·H2O), and characterized by elemental analysis, IR spectroscopy, TG-DTG, and X-ray diffraction analysis. TG-DTG with X-ray powder diffraction showed that these compounds could decompose to lanthanide sulfides at relatively lower temperature, which indicated that the title complexes could be favorable precursors to prepare lanthanide sulfides.     

Relationship between Crystal Structure and Luminescence Properties of （Y0.96-x Lnx Ce0.04 ）3 Al5 O12 （LH=Gd,La, Lu） Phosphors

The doping effects of La^3＋, Gd^3＋ and Lu^3＋ on the crystal structure and luminescence properties of （Yo96-x LnxCe0.04）3Al5O12（Ln = Gd, La, Lu） phosphors were studied. The X-ray diffraction patterns presented that with the inerease of the doping concentrations of La^3＋ and Gd^3＋ ions, the d-value of （Y0.96-xLnxCe0.04）3Al5O12 （Ln = Gd, La） inereased and the larger the doping ion, the stronger the effect would be. The doping amount causing phase transition in （Y0.96-xLnxCe0.04）3Al5O12 decreased with the inerease of the ionic radii of the doping lanthanide ions （La^3＋： 0.106 nm, Gd^3＋： 0. 094 nm, Lu^3＋ ： 0.083 nm）. The bigger doping ion of Gd^3＋ made the emission of （Y0.96-xGdxCe0.04）3Al5O12 move to red spectral region, but the smaller one of Lu^3＋ made it blue.     

Synthesis, Characterization and Crystal Structure of Neutral Homoleptic Lanthanide Amide Yb（NPh2）3（THF）2

A neutral homoleptic lanthanide amide Yb(NPh2)3(THF)2 was obtained by reaction of anhydrous YbCl3 with LiNPh2 in THF. The product was characterized by elemental analysis, infrared spectrum and X-ray crystallographic analysis. The crystal data are monoclinic, P21/n space group, a=1.2052(2) nm, b=1.9369(3) nm, c=1.6523(2) nm, β=92.79(1)°, V=3.8524(9) nm3, Z=4, Dc=1.417 g*cm-3, μ=24.67 cm-1 (Mo Kα), F(000)=1668, R=0.036, Rw=0.039. The central metal ytterbium is coordinated by three terminal NPh2 groups and two THF molecules to form a five-coordinate distorted trigonal bipyramid. The mean Yb-N bond length is 0.2219(6) nm.     

Synthesis, Characterization and Crystal Structure of Neutral Homoleptic Lanthanide Amide Yb(NPh_2)_3(THF)

Ｌａｎｔｈａｎｉｄｅａｍｉｄｅｃｏｍｐｌｅｘｅｓａｒｅａｎｉｍ ｐｏｒｔａｎｔｃｌａｓｓｏｆｐｒｅｃｕｒｓｏｒｓｆｏｒｌａｎｔｈａｎｉｄｅｄｅｒｉｖａｔｉｖｅｓ .Ｉｔｃａｎｂｅｅａｓｉｌｙｔｒａｎｓｆｏｒｍｅｄｔｏｃｏｒ ｒｅｓｐｏｎｄｉｎｇｌａｎｔｈａｎｉｄｅｃｏｍｐｌｅｘｂｙｒｅａｃｔｉｎｇｗｉｔｈｉｎｖｏｌｖｉｎｇｐｒｏｔｉｃｒｅａｇｅｎｔｓ[1,2 ] .Ｔｈｅｌａｎｔｈａｎｉｄｅａｍｉｄｅｕｓｅｄａｓｓｙｎｔｈｅｔｉｃｐｒｅｃｕｒｓｏｒｉｓｎｅｕｔｒａｌｈｏｍｏｌｅｐｔｉｃｃｏｍｐｌｅｘ ,ｏｔｈ…     

Phase Behavior of BaLn2Mn2O7（Ln = Rare Earth） with a Layered Perovskite Structure

Many phases appear in BaLn2Mn2O7 family (Ln = rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K2NiF4 type stru,ture, although the X-ray diffraction patterns are clearly different : a little deformation or tilting of the oxygen oetahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb2Mn2O7, was refined including the data of high temperature X-ray diffractometry.     

Synthesis and photoluminescence studies of Ba(Gd,Ln)B9O16:Eu3+(Ln=La,Y) phosphors for n-UV LED lighting and display devices

BaGdB9O16:Eu3+ and Ba(Gd,Ln)B9O16:Eu3+(Ln=La, Y) phosphors were synthesized by solid state diffusion method. The X-ray diffraction, scanning electron microscopy(SEM) and photoluminescence properties were investigated. The as-synthesized BaGdB9O16:Eu3+ and Ba(Gd,Ln)B9O16:Eu3+(Ln=La, Y) phosphors showed strong red emission under ultraviolet light excitation. By partially substituting Gd3+ by La3+ and Y3+ ions in the host BaGdB9O16:Eu3+ materials, the maximum emission intensity was observed for the optimum composition of BaGd0.91La0.8B9O16Eu0.01 phosphor. The experimental results indicated that the Eu doped BaGdB9O16 and Ba(Gd,Ln)B9O16(Ln=La, Y) phosphors were promising red phosphors, which might find potential applications in near-UV excited LED lighting as well as display devices. Comparison of as-synthesized phosphors with standard phosphor used in CFL(compact fluorescent lamp) was also done. Energy transfer mechanism of Gd3+ to Eu3+ was also discussed in this paper.     

Lanthanide Complex [Nd(dpdo)_4(H_2O)_3][ClO_4]_3·4.5H_2O·dpdo Containing Framework Based on 4,4′-Dipyradine-Dioxide

Ｃｒｙｓｔａｌｅｎｇｉｎｅｅｒｉｎｇｏｆｃｏｏｒｄｉｎａｔｉｏｎｐｏｌｙ ｍｅｒｓｗｉｔｈｏｐｅｎｆｒａｍｅｗｏｒｋｓａｓｓｅｍｂｌｅｄｆｒｏｍｏｒ ｇａｎｉｃ ｍｅｔａｌｃｏｍｐｏｕｎｄｓｈａｓｂｅｅｎｏｆｇｒｅａｔｉｎｔｅｒ ｅｓｔｓｏｗｉｎｇｔｏｔｈｅｉｒｐｏｔｅｎｔｉａｌｐｒｏｐｅｒｔｉｅｓａｓｎｏｖｅｌｍａｔｅｒｉａｌｓｓｕｃｈａｓｇａｓａｄｓｏｒｐｔｉｏｎ[1,2 ] ,ｉｏｎ ｅｘ ｃｈａｎｇｅ[3] ａｎｄｃａｔａｌｙｓｉｓ[4] .Ｔｈｅｃｏｎｓｔｒｕｃｔｉｏｎｏｆｃｏｏｒｄｉｎａｔｉｏｎｐｏｌｙｍ…     

Synthesis and Characterization of Ln(NO_3)_3-Phen-Fu Ternary Complexes

ＳｙｎｔｈｅｓｉｓａｎｄＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆＬｎ（ＮＯ３）３ＰｈｅｎＦｕＴｅｒｎａｒｙＣｏｍｐｌｅｘｅｓＬｉｎＪｉｙｕｎ（林纪筠），ＭａＤｅｊｉａｎ（马德建）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＥａｓｔＣｈｉｎａＮｏｒｍ...     

Spectroscopic and fluorescence properties of Sm~(3+)-doped zincfluorophosphate glasses

Optical absorption and fluorescence spectra of Sm3＋-doped zincfluorophosphate glasses with molar composition of 44P2O5＋17K20＋9Al2O3＋（30-χ）ZnF2＋χSm2O3 （χ=0.01 mol.%, 0.05 mol.%, 0.1 mol.%, 0.5 mol.%, 1.0 mol.%, 2.0 and 3.0 mol.%） referred as PKAZFSm were prepared by melt quenching technique and were characterized through Raman, absorption, emission and decay curve analysis. From the absorption spectra, Judd-Ofelt intensity parameters were determined and were used to predict radiative properties such as transition probabilities （AR, radiative lifetimes （τR）, branching ratios （βR）, effective bandwidths （△λeff） and stimulated emission cross-section （σ（λp）） for the excited 4G5/2 luminescent level. The decay curve for the 4G5/2 level was single exponential for lower concentration and became non-exponential for higher concentrations. The non-exponential nature of the decay curves of the 4G5/2 level increased with increase in Sm3＋ ions concentration accompanied by decrease in lifetime due to energy transfer processes among the Sm3＋ ions. The non-exponential decay curves was well fitted to the generalized Inokuti-Hirayama model for S=6, indicating that the energy transfer among optically active ions was of dipole-dipole interaction. The cross-relaxation mechanism responsible for the quenching of lifetimes and the effect of variation of concentration on the spectroscopic properties were also discussed.     

Investigation on pumping oxygen characteristics of (Bi2O3)0.73(Y2O3)0.27 solid electrolyte

(Bi2O3)0.73(Y2O3)0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen characteristics in non-dehydrated Ar gas were investigated, where a ZrO2 (Y2O3 stabilized) oxygen sensor was used to measure the oxygen partial pressure Po2. The results showed that the Po2 value reached magnitudes of 1×10-20-1×10-10 Pa at the applied pumping oxygen voltage of 0.5 V, 1×10-37-1×10-27 Pa at 1.0 V and 1×10-53-1×10-47 Pa at 2.0 V within the temperature range from 550 to 650 ℃. Moreover, no cracks were found in the tested solid electrolyte tubes. Thus, the Bi2O3-Y2O3 system might be used in solid electrolyte oxygen pump for purifying gases.