Luminescent Properties of A Novel Terbium Complex Tb（o-BBA）3（phen）

A novel rare earth complex of terbium ion with 2-benzoylbenzoic acid and 1, 10-phenathroline （Tb（o-BBA）3 （phen）, o-BBA-2-benzoylbenzoic acid, phen = 1, 10-phenathroline） was used as an electroluminescent material for the first time. The Tb complex was blended with poly（N-vinylcarbazole） （PVK） in different weight ratios and spinn to coated into films （noted as PVK ：Tb films）. The photoluminescence （PL） properties of films were investigated and the optimum weight ratio between PVK and Tb（o-BBA）3（phen） was found to be 3：1. Monolayer devices with the structure ITO/PVK： Tb/AI were fabricated and emitted green light, which was characteristic of Tb^3＋ emission. The results show that mecha- nisms for PL and EL are different. The PL is considered to be caused because of energy transfer and direct excitation to the Tb（o-BBA）3（phen） molecule, while EL is mainly on charging trapping.     

Hydrothermal Synthesis and Crystal Structure of a New Dimeric Lanthanum （Ⅲ） Complex

Recently ,considerableefforthasbeenfocusedonrareeartharomaticcarboxylatecomplexesduetotheirfascinatingstructuraldiversities ,variouscoordinationmodesandpromisingfunctionalproperties[1～ 3] .Car boxylateanionshaveversatilecoordinationmodesandthelanthanideionsarewellknownforthevariableco ordinationnumberfrom 3to 12 [4 ] ,whichhavebeenutilizedinpreparingpolymerwithone ,two ,andthree dimensionalstructures[5～ 7] .Althoughmanycomplexeswithbenzoateortheirderivativeshavebeenreported[8～ 11] ,theywere…     

Synthesis and Upconversion Luminescence of LaF3 ： Yb^3＋ , Er^＋/SiO2 Core/Shell Microcrystals

LaF3：Yb^3＋ , Er^＋ microcrystals were synthesized by a hydrothermal method, and then, the LaF3： Yb^3＋ , Er^＋ microcrystals were coated with silica. Phase identification of LaF3： Yb^3＋ , Er^＋ and LaF3： Yb^3＋ , Er^＋/SiO2 was performed via XRD. The TEM image showed that the size of LaF3： Yb^3＋ , Er^＋ was 150 nm and LaF3： Yb^3＋ , Er^＋/SiO2 presented clearly a core/shell structure with 20 nm shell thickness. The upconversion spectra of LaF3： Yb^3＋ , Er^＋ and LaF3： Yb^3＋ , Er^＋/SiO2 in solid state and in ethanol were studied with a 980 nm diode laser as the excitation source. The upconversion spectra showed that the silica shell had little effect on the properties of fluorescence of the LaF3：Yb^3＋ , Er^＋ microcrystals. At the same time, the green luminescence photo of LaF3： Yb3＋, Er3＋/SiO2 in the PBS buffer was obtained, which indicated that the LaF3： Yb^3＋ , Er^＋/SiO2 could be used in biological applications.     

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 and Characteristic Study on Complexes of Europium（Ⅲ） and Maleic Acid Doped with Non-Fluorescent Ions

Complex of europium （Ⅲ） with maleic acid, and binuclear complexes of europium（Ⅲ）with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8：2. The order of Eu^3＋ fluorescence strengthened by three doped rare earths was Gd^3＋ 〉La^3＋ 〉Y^3＋     

Spectral Properties and Upconversion Luminescence of Er^3＋, yb^3＋： BaWO4 Crystal

The optical quality of Er^3＋, yb^3＋： BaWO4 crystal was gown by Czochralski method. Absorption spectra were measured and energy levels were assigned. According to Judd-Ofelt theory, the spectral strength parameters of Er^3＋ ion were fitted to beΩ2 =0.3926 x 10^-20 cm^2, Ω4 =0.0721×10^-20 cm^2, Ω6 =0.0028 ×10.20 cm^2. Emission peaks centered at around 523,544 and 670 nm were observed under 334 nm He-Cd laser excitation and emission peaks centered at 1001 and 1534 nm were detected under 976 nm laser excitation. Strong green emission was also observed when the crystal was pumped with 808 nm and 976 nm laser. The mechanisms of frequency upconversion and sensitization were analyzed.     

Synthesis and Fluorescence Properties of Europium,Terbium Doped Zn^2＋, Cd^2＋, and Cr^3＋ Complexes

Europium and terbium complexes with strong fluorescence intensity and long fluorescence lifetime were prepared. By replacing half of the europium or terbium ion with M （M = Zn^2＋, Cd^2＋, and Cr^3＋） using the doped method, and then incorporating it with 18-crown-6 ether and terephthalic acid, six heteronuclear samples EuZnLL＇Cl3·3H2O（1）, EuCdLL2＇Cl3·5H2O（2）, EuCrLL＇Cl4· 4H2O（3）, TbZnLL＇Cl3·4H2O（4）, TbCdLL＇2Cl3·4H2O（5）, and TbCrLL＇2Cl4 ·4H2O（6） （L = terephthalic acid, L＇= 18-Crown-6 ether） were obtained. The elemental analysis, molar conductivities, rare earth complexometry, Fourier Transform Infrared Spectroscopy （FT-IR）, ultraviolet （UV）, TGA, fluorescence intensity, and fluorescence lifetime of the samples were measured. The results showed that there were good luminescence properties for heteronuclear complexes （1）, （2）, （4）, and （5）, which were even stronger than those of the homonuclear complexes Eu2LL＇2Cl4·4H2O and Tb2LL＇2Cl4 ·4H2O, but the luminescence properties of EuCrLL＇Cl4·4H2O, TbCrLL＇Cl4·4H2O were very weak. A possible luminescence mechanism was suggested by the organic-inorganic doped mechanism and the law of intramolecular energy transfer.     

Optimization and Calculation of TbCl3-ACl（A = Li, Na, K, Rb, Cs）Phase Diagrams

Thermodynamic information of the melts involvingrare earth halides and alkali halides plays an importantrole in the preparation of rare earth metals by moltensalt electrolysis and by metallothermic reduction. Theknowledge of thermodynamics of molten s…     

Hydrothermal synthesis and crystal structure study of two novel 3-D mellitates {Nd2[C6（COO）6] （H2O）6} and {Ho2[C6（COO）6]（H2O）6}

Two novel 3-D coordination compounds, Nd2[C6（COO）6]（H2O）6 （1）and Ho2[C6（COO）6]（H2O）6 （2）, were hydrothermaily synthesized from mellitic acid and neodymium perchlorate （or holmium perchlorate） in the alkaline aqueous solution and characterized with elemental analysis, TG, IR spectrum, and single crystal X-ray diffraction. The two compounds were isostructural and crystallized in the orthorhombic system, space group Pnnm, with a=1.3531 （4） nm, b=0.6687 （2） nm, c=1.0224（3） nm, V=0.92523（5） nm^3, Z=4, D=2.630 g/cm^3, F（000）=696.0, Goof=1.052. Final R indices [1 〉2∑（Ⅰ）]： R1=0.0195, wR2=0.0382 for 1; a=1.3411 （2） nm, b=0.6586（1） nm, c=1.0116（2） nm, V=0.8935（3） nm^3, Z=4, D=2.877 g/cm^3, F（000）=724.0, Goof=1.061. Final R indices [1 〉2∑（Ⅰ）]： R1=0.0200, wR2=0.0479 for 2. In the two compounds 1 and 2, the mellitic acid ligand, in which all the carboxylate groups were deprotonated, had only one kind of coordination mode to bridge metal ions to form four-connected three-dimensional diamondiod networks.     

Syntheses,characterization, and luminescence of two lanthanide complexes [Ln2（acetate）6（HeO）4]·4H2O （Ln=Tb（1）, Sm（2））

Two dinuclear compounds [Ln2（acetate）6（H2O）4]-4H2O （Ln=Tb（1）, Sm（2）） were obtained by the hydrothermal reaction of Ln2O3 with malonic acid at 150 ℃. Both compounds were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction. The results showed that complexes 1 and 2 were isomorphous and crystallize in triclinic space group P 1. The coordination geometry around Ln（Ⅲ） ions in the complexes 1 and 2 was a distorted tricapped trigonal prism with a nine coordination. In the crystal, the molecular organization was further stabilized by well-defined weak hydrogen bonding interactions between the neutral dinuclear molecular units that led to the formation of a three-dimensional network. The fluorescence properties of the two complexes 1 and 2 in organic solvents were also studied. The results show that the ligand acetate favored energy transfer to the emitting energy level of Tb（Ⅲ） in complex 1. Some factors that influence the fluorescent intensity were also discussed in the article.     

Structure and Dielectric Study of Ce3 NbO7＋δ

The structure, phase composition, and migration of oxygen ion in Ce3 NbO7＋δ were reported on the basis of lone-pair substitution concept. X-ray diffraction study revealed that Ce3 NbO7＋δ sample was comprised of Ce3 NbO7＋δ phase and CeNbO4.25 phase. In the dielectric study of Ce3 NbO7＋δ sample, two dielectric loss peaks were observed both in temperature spectra and frequency spectra. Both peaks were shifted towards higher temperature with increase in frequency in temperature spectra and towards higher frequency with increase in temperature in frequency spectra, indicating the relaxation essence of these two peaks. It was suggested that the short distance diffusions of oxygen ions in both Ce3 NbO7＋δ phase and CeNbO4.25 phase gave rise to the two dielectric relaxation peaks.     

Crystal structure and infrared spectrum of thallium holmium polyphosphate,TIHo（PO3）4

Crystals of thallium-holmium polyphosphate T1Ho（PO3）4 were grown by flux method technique and characterized by single crystal X-ray diffraction. Structure of T1Ho（PO3）4 was solved for the first time, and it crystallized in the monoclinic P21/n space group with the following unit-cell dimensions： a=1.02225（3） nm, b=0.88536（2） nm, c=1.09541（4） nm, β=105.888（1）°, V=0.95354（5） nm^3 and Z=4. The crystal structure was solved from 2174 independent reflections with final R1（F^2）=0.0442 and Rw（F^2）=0.0861 refined with 164 parameters. The atomic arrangement could be described as a long chain polyphosphate organization. Holmium atoms had eightfold coordination. The structure of T1Ho（PO3）4 consisted of HoO8 polyhedra sharing oxygen atoms with phosphoric group PO4. Infrared spectrum was investigated at room temperature in the frequencies range, 350--4000 cm^-1, showing some characteristic vibration bands of infinite chain structure of PO4 tetrahedra linked by bridging oxygen.     

Flux and concentration effect on Eu^3＋ doped Gd2（MoO4）3 phosphor

A novel red emitting phosphor Gd2（MoO4）3：Eu^3＋ was prepared by solid reaction, using Gd2O3, Eu2O3 and WO3 as starting matedals and NH4F as flux. The effects of flux content and Eu^3＋ concentration on the crystal structure, morphology and luminescent properties were investigated using XRD, SEM and fluorescent spectrum measurement. The XRD patterns showed that the resultants had the monoclinic structure. With the increase in flux amount, their crystallization significantly improved. The SEM images indicated that the mean size of the phosphor particles was around 2 μm, and agglomeration of the phosphor particles appeared while introducing higher flux amount. The excitation spectra exhibited more intense f-f transitions originating from ground state 7^F0 to upper states 5^L6 and 5^D2 than the charge transfer band. The concentration quenching of Eu^3＋ emission indicated that energy transfer from Eu^3＋ to molybdate host existed even at lower Eu^3＋ concentration.     

Luminescent properties of amorphous phosphor 1.4YeO3·2.5Al2O3·0.1Tb2O3 prepared by sol-gel method

Amorphous phosphor 1.4YeO3·2.5Al2O3·0.1Tb2O3 （the same composition as Y2.8Tb0.2Al5O12） was prepared via a sol-gel method at relatively low temperature （i.e., below 650℃）, which is much lower than that for the preparation of polycrystalline Y3Al5O12：Tb^3＋ （above 1400℃）. The amorphous phosphor prepared in the optimized conditions showed a bright green-yellowish luminescence, the intensity of which was comparable with that of polycrystalline sample and the emissions of which were assigned to 5D4 → 7Fj transitions of Tb^3＋. Besides the emissions of Tb^3＋, the amorphous samples prepared at temperatures below 500 ℃ presented a weak blue emission band around 420 nm.     

Paramagnetic Anisotropy of CdGd2（WO4） 4-δ Single Crystal

CdGd2 （WO4）4 -δ single crystal was grown using the Czochralski＇s method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of （WO4）^2- , therefore, there were some Gd^2＋ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance （ESR） experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2＋ and Gd^3｜ ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3＋ ions to 63.2% of Gd^2＋ ions in the Gd ions of the CdGd2（WO4）4-δ crystal was calculated, and δ was 0.638 in the single crystal.     

Synthesis and Crystal Structure of a 4f-3d Complex [La(DMF)_6(H_2O)_3][Cr(CN)_6]·2H_2O

Ｒｅｃｅｎｔｌｙ ,ｔｈｅｒｅｈａｓｂｅｅｎｃｏｎｓｉｄｅｒａｂｌｅｉｎ ｔｅｒｅｓｔｉｎｌａｎｔｈａｎｉｄｅ(Ⅲ )ｈｅｘａｃｙａｎｏｆｅｒｒａｔｅｓａｎｄｔｈｅａｎａｌｏｇｏｕｓｃｏｂａｌｔ(Ⅲ )ａｓｗｅｌｌａｓｃｈｒｏｍｉｕｍ(Ⅲ )ｃｏｍｐｌｅｘｅｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｐｏｔｅｎｔｉａｌａｓｃａｔａｌｙｔｉｃ ,ｓｅｍｉｃｏｎｄｕｃｔｉｖｅ ,ａｎｄｍａｇｎｅｔｉｃｍａｔｅ ｒｉａｌｓ[1～ 4] .Ｆｏｒｅｘａｍｐｌｅ ,ｍａｇｎｅｔｉｃｓｔｕｄｉｅｓｏｎａｓｅｒｉｅｓｏｆｔｈｒｅｅ ｄｉｍｅｎｓｉｏ…