K3Eu5(PO4)6: hydrothermal synthesis,crystal structure and photoluminescence properties

An anhydrous orthophosphate, K₃Eu₅(PO₄)₆ (tripotassium pentaeuropium hexaphosphate), has been prepared by a high‐temperature solid‐state reaction combined with hydrothermal synthesis, and its crystal structure was determined by single‐crystal X‐ray diffraction analysis (SC‐XRD). The results show that the compound crystallizes in the monoclinic space group C2/c and the structure features a three‐dimensional framework of [Eu₅(PO₄)₆]_∞, with the tunnel filled by K⁺ ions. The IR spectrum, UV–Vis spectrum and luminescence properties of polycrystalline samples of K₃Eu₅(PO₄)₆, annealed at temperatures of 650, 700, 750, 800 and 850 °C, were investigated. Although with a full Eu³⁺ concentration (9.96 × 10²¹ ions cm^?3), the self‐activated phosphor K₃Eu₅(PO₄)₆ shows s strong luminescence emission intensity with a quantum yield of 37%. Under near‐UV light excitation (393 nm), the series of samples shows the characteristic emissions of Eu³⁺ ions in the visible region from 575 to 715 nm. The sample sintered at 800 °C gives the strongest emission and its lifetime sintered at 800 °C (1.88 ms) is also the longest of all.     

Synthesis, crystal structure and luminescence properties of europium complexes with a new terpyridine-like ligand

New 1:1, 1:2 and 1:3 europium (Ⅲ) complexes with 2,4,6-tris(3,5-dimethylpyrazol-1-yl)-1, 3,5-triazine have been prepared, and their luminescence has been demonstrated to be sensitive to the π-π stacking and H-bonding interactions.     

A new noncentrosymmetric vanadoborate: synthesis, crystal structure and characterization of K2SrVB5O12

A new noncentrosymmetric vanadoborate compound, K(2)SrVB(5)O(12), is synthesized by the high temperature solution method. It crystallizes in the monoclinic space group P2(1) (no. 4) with lattice constants a = 6.618(3) ?, b = 8.378(4) ?, c = 9.974(5) ?, β = 99.789(6)°, Z = 2. The structure consists of vanadoborate anionic layers with K(+) and Sr(2+) cations filling the void spaces via electrostatic interactions to form the three-dimensional network. The TG-DSC curves and the UV-Vis-NIR diffuse reflectance spectrum were measured. Band structures and density of states were calculated. The powder second harmonic generation (SHG) effect of K(2)SrVB(5)O(12) is similar to that of KH(2)PO(4) (KDP).     

A new langbeinite‐type phosphate K2GdHf(PO4)3: synthesis,crystal structure,band structure and luminescence properties

Langbeinite‐type compounds are a large family that include phosphates, sulfates and arsenates, and which are accompanied by interesting physical properties. This work reports a new disordered langbeinite‐type compound, K₂GdHf(PO₄)₃ [dipotassium gadolinium hafnium tris(phosphate)], and its structure as determined by single‐crystal X‐ray diffraction. Theoretical studies reveal that K₂GdHf(PO₄)₃ is an insulator with a direct band gap of 4.600 eV and that the optical transition originates from the O‐2p→Hf‐5d transition. A Ce³⁺‐doped phosphor, K₂Gd_0.99Ce_0.01Hf(PO₄)₃, was prepared and its luminescence properties studied. With 324 nm light excitation, a blue emission band was observed due to the 5d¹→4f¹ transition of Ce³⁺. The average luminescence lifetime was calculated to be 5.437 µs and the CIE chromaticity coordinates were (0.162, 0.035). One may expect that K₂Gd_0.99Ce_0.01Hf(PO₄)₃ can be used as a good blue phosphor for three‐colour white‐light‐emitting diodes (WLEDs).     

Synthesis, crystal structure, magnetic and luminescence properties of KEuGe2O6: a europium cyclogermanate containing infinite chains of edge-sharing Eu-O polyhedra

A new Eu(III) germanate, KEuGe2O6, has been synthesized by both the flux-growth method and the high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction. The compound contains parallel zigzag chains of edge-sharing Eu-O polyhedra, which are in turn linked by sharing vertices and edges with three-membered single ring Ge3O9(6-) germanate anions to form a 3-D framework structure. The magnetic and luminescence properties were also investigated. The observed chiMT value at 300 K is 4.53 emu K mol(-1), which is in good agreement with the calculated value for three Eu3+ ions. The sharp peaks in the room-temperature emission spectrum are assigned. The number of lines in the region of the 5D0-->7F0 transition and the relative intensities of the 5D0-->7F1 and 5D0-->7F2 transitions confirm the presence of two local Eu3+ environments and strongly distorted Eu3+-ligand surroundings. The reasons for the very short emission life time is discussed. The Sm and Tb analogues have also been synthesized.     

Synthesis,crystal structure,and luminescence properties of a novel europium(III) complex

A novel europium(III) complex, [Eu(C₇H₅O₂)₂(C₇H₆O₂)₂(C₁₂H₈N₂)₂Cl], was synthesized and characterized by elemental analysis and single-crystal X-ray determination. It crystallizes in the monoclinic system, space group Cc with a = 17.2814(16), b = 17.9421(17), c = 14.9971(14) Å, β = 101.6510(10)°, Z = 4, ρ _c = 1.508 g/cm³, μ = 1.496 mm^?1, the final R = 0.0516 and wR = 0.1267 for 6435 observed reflections with I > 2σ(I). Structural analysis shows that the Eu(III) atom is nine-coordinated by one chlorine atom, four N atoms of two 1,10-phenanthroline (Phen) ligands, and four O atoms from four carboxybenzene ligands, to form a distorted tricapped trigonal prism. The luminescence spectrum of the complex indicates that the intensity of the emission wavelength at 612 nm is strongest among all emission wavelengths and the second phen ligand shows an enhancement effect on the luminescence of the complex.     

Synthesis,crystal structure,and luminescence properties of a one-dimensional europium(III) polymer

In the title complex, [Eu₂(C₈H₇O₃)₆(C₁₂H₈N₂)₂] _n , which has an inversion center midway between two Eu(III) atoms of the structural unit, forms a one-dimensional polymer bridged by two mondentate, two bidentate, and two tridentate carboxylate groups with an Eu-Eu separation of 4.1853(7) Å. Each Eu atom is nine-coordinated by two N atoms of a 1,10-phenanthroline (phen) ligand and seven O atoms from six phenoxyacetate ligands, to form a distorted tricapped trigonal prismatic. The luminescence spectrum of the polymer indicates that the intensity of the emission wavelength at 619 nm is the strongest among all emission wavelengths and the second phen ligand shows an enhancement effect on the luminescence of the complex.     

Flux synthesis, crystal structures, and luminescence properties of salt-inclusion lanthanide silicates: [K9F2][Ln3Si12O32] (Ln = Sm, Eu, Gd)

New salt-inclusion lanthanide silicates, [K 9F 2][Ln 3Si 12O 32] (Ln = Sm, Eu, Gd), have been synthesized using a KF-MoO 3 flux, and structurally characterized by single-crystal and powder X-ray diffraction. The structures of these three isostructural compounds consist of open-branched funfer silicate single layers with six-, eight-, and twelve-membered rings, which are connected via LnO 6 octahedra to form a 3-D framework. The F (-) and K (+) ions are located in the structural channels and form a F 2K 7 dimer with a structure similar to that of Cl 2O 7. The photoluminescence properties of the Eu compound have also been studied. The sharp peaks in the room-temperature emission spectrum are assigned and the relative intensities of the (5)D 0 --> (7)F 1 and (5)D 0 --> (7)F 2 transitions are consistent with the crystallography results. Crystal data for the Eu compound: triclinic, space group P1 (No. 2), a = 6.8989(2) A, b = 11.3834(4) A, c = 11.4955(4) A, alpha = 87.620(2) degrees , beta = 89.532(2) degrees , gamma = 80.221(2) degrees , and Z = 2. Crystal data for the Sm compound: The same as those for the Eu compound except a = 6.9152(6) A, b = 11.400(1) A, c = 11.531(1) A, alpha = 87.610(1) degrees , beta = 89.445(1) degrees , and gamma = 80.081(1) degrees .     

Synthesis,crystal structure,and luminescence of a quaternary binuclear europium complex [Eu2(phth)2(Hphth)2(phen)2(H2O)4]

A quaternary binuclear europium complex [Eu₂(phth)₂(Hphth)₂(phen)₂(H₂O)₄] (H₂phth?=?phthalic acid, phen?=?1,10-phenanthroline) has been synthesized. The structure was determined by X-ray crystallography which reveals that it is binuclear with each europium nine-coordinate. Intermolecular hydrogen bonds link the complex units to form a 3D supermolecular network. Its properties have been studied by means of luminescence spectrum and thermal analysis. Fluorescence spectra show that the complex exhibits strong red emission.     

Synthesis,crystal structure and properties of a new congruently melting compound,K3ZnB5O10

A new compound, K₃ZnB₅O₁₀, has been synthesized by solid-state reaction. It crystallizes in the monoclinic system, space group P2₁/n with unit–cell parameters a = 7.6391(5) Å, b = 19.2304(13) Å, c = 7.6905(5) Å, β = 116.698(4)° and Z = 4. The structure of the compound is solved by the direct methods and refined to R1 = 0.0286 and wR2 = 0.0600. K₃ZnB₅O₁₀ contains a two-dimensional ZnB₅O₁₀ layer, which forms by connecting isolated double ring [B₅O₁₀] groups and ZnO₄ tetrahedra. The K atoms filling in the interlayer and intralayer link the layers together. Functional groups presented in the sample were identified by FTIR spectrum. UV–vis–NIR diffuse reflectance spectrum exhibits ultraviolet cutoff edge is about 190 nm. The DSC analysis proves that K₃ZnB₅O₁₀ is a congruently melting compound.     

Synthesis,crystal structure and luminescence of three europium complexes with 2-iodobenzoic acid

Three new complexes, [Eu(2-IBA)₃?·?H₂O] _n (1), [Eu(2-IBA)₃?·?2,2′-bpy]₂ (2), and [Eu(2-IBA)₃?·phen]₂ (3) (2-IBA?=?2-iodobenzoato; 2,2′-bpy?=?2,2’-bipyridine; phen?=?1,10-phenanthroline) were synthesized, and their crystal structures determined by X-ray diffraction. In complex 1, Eu³⁺ ions are linked through carboxylate groups via bridging – chelating – bridging coordination modes to form a one-dimensional polymeric chain. The carboxylate groups are tetradentate-bridged. Complex 2 is binuclear with an inversion center, in which europium is nine-coordinated with seven oxygen atoms from five 2-IBA ligands and two nitrogen atoms from one 2,2′-bpy molecule in a distorted monocapped square antiprism. The crystal structure of 3 is similar to that of 2. These complexes emit red light luminescence. The ⁵ D ₀?→?⁷ F _j (j?=?1–4) transition emission of Eu³⁺ ion has been observed.     

Electronic structure,morphology-controlled synthesis,and luminescence properties of YF3: Eu3+

Journal of Sol-Gel Science and Technology - Studying electronic structure plays a key role in improving the photoluminescence (PL) properties of materials. Therefore, the electronic structure of...     

Hydrothermal synthesis,crystal structure,and solid-state NMR spectroscopy of a new indium silicate: K2In(OH)(Si4O10)

A new indium(III) silicate, K(2)In(OH)(Si(4)O(10)), has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the monoclinic space group P2(1)/m (No. 11) with a = 11.410(1) A, b = 8.373(1) A, c = 11.611(1) A, beta = 112.201(2) degrees, and Z = 4. The structure, which is analogous to that of K(2)CuSi(4)O(10), consists of unbranched vierer 4-fold chains of corner-sharing SiO(4) tetrahedra running along the b axis linked together via corner sharing by chains of trans-corner-sharing InO(4)(OH)(2) octahedra to form a 3-D framework which delimits 8-ring and 6-ring channels to accommodate K(+) cations. The presence of hydroxyl groups is confirmed by IR spectroscopy. The (29)Si MAS NMR exhibits four resonances at -88.6, -90.1, -97.4, and -98.2 ppm corresponding to four distinct crystallographic Si sites. A (1)H --> (29)Si CP/MAS NMR experiment was performed to assign the four resonances.     

High-pressure synthesis, crystal structure, and properties of BiPd2O4 with Pd2+ and Pd4+ ordering and PbPd2O4

BiPd(2)O(4) and PbPd(2)O(4) were synthesized at high pressure of 6 GPa and 1500 K. Crystal structures of BiPd(2)O(4) and PbPd(2)O(4) were studied with synchrotron X-ray powder diffraction. BiPd(2)O(4) is isostructural with PbPt(2)O(4) and crystallizes in a triclinic system (space group P1, a = 5.73632(4) ?, b = 6.02532(5) ?, c = 6.41100(5) ?, α = 114.371(1)°, β = 95.910(1)°, and γ = 111.540(1)° at 293 K). PbPd(2)O(4) is isostructural with LaPd(2)O(4) and BaAu(2)O(4) and crystallizes in a tetragonal system (space group I4(1)/a, a = 5.76232(1) ?, and c = 9.98347(2) ? at 293 K). BiPd(2)O(4) shows ordering of Pd(2+) and Pd(4+) ions, and it is the third example of compounds with ordered arrangements of Pd(2+) and Pd(4+) in addition to Ba(2)Hg(3)Pd(7)O(14) and KPd(2)O(3). In PbPd(2)O(4), the following charge distribution is realized Pb(4+)Pd(2+)(2)O(4). PbPd(2)O(4) shows a structural phase transition from I4(1)/a to I2/a at about 240 K keeping basically the same structural arrangements (space group I2/a, a = 5.77326(1) ?, b = 9.95633(2) ?, c = 5.73264(1) ?, β = 90.2185(2)° at 112 K). BiPd(2)O(4) is nonmagnetic while PbPd(2)O(4) exhibits a significant temperature-dependent paramagnetic moment of 0.46μ(B)/f.u. between 2 and 350 K. PbPd(2)O(4) shows metallic conductivity, and BiPd(2)O(4) is a semiconductor between 2 and 400 K.     

High-pressure synthesis, crystal structure, and electromagnetic properties of CdRh2O4: an analogous oxide of the postspinel mineral MgAl2O4

The postspinel mineral MgAl(2)O(4) exists only under the severe pressure conditions in the subducted oceanic lithosphere in the Earth's deep interior. Here we report that its analogous oxide CdRh(2)O(4) exhibits a structural transition to a quenchable postspinel phase under a high pressure of 6 GPa at 1400 °C, which is within the general pressure range of a conventional single-stage multianvil system. In addition, the complex magnetic contributions to the lattice and metal nonstoichiometry that often complicate investigations of other analogues of MgAl(2)O(4) are absent in CdRh(2)O(4). X-ray crystallography revealed that this postspinel phase has an orthorhombic CaFe(2)O(4) structure, thus making it a practical analogue for investigations into the geophysical role of postspinel MgAl(2)O(4). Replacement of Mg(2+) with Cd(2+) appears to be effective in lowering the pressure required for transition, as was suggested for CdGeO(3). In addition, Rh(3+) could also contribute to this reduction, as many analogous Rh oxides of aluminous and silicic minerals have been quenched from lower-pressure conditions.     

Morphology controllable synthesis and luminescence properties of NaLa(WO4)2:Eu microcrystals

NaLa(WO₄)₂:Eu microcrystals with shapes of four-arris shuttle, quadrangled star, and quadrangled dendrite were hydrothermally synthesized at 180 °C for 16 h. The concentration of the reactants and cetyltrimethyl ammonium bromide (CTAB) influenced the morphologies of the products. As La(NO₃)₃, Na₂WO₄ and CTAB was 0.375, 1.0, and 1.0 mmol, respectively, four-arris shuttle was obtained. As the concentration of the reactants doubled and the amount of CTAB ranged from 0.4 to 2.0 mmol, quadrangled dendrite, quadrangled star and four-arris shuttle were prepared, respectively. Luminescence intensity measurement of the three morphologies of NaLa(WO₄)₂:Eu showed that quadrangled dendrite was the strongest and four-arris shuttle was the lowest.     

K2[Te4O8(OH)10]: synthesis,crystal structure and thermal behavior

Dipotassium octaoxodecahydroxotetratellurate, K₂[Te₄O₈(OH)₁₀], has been prepared hydrothermally in acidic medium under autogenous pressure. It crystallizes in space group P2₁/c of the monoclinic system with Z=2 in a cell of dimensions a=5.592(1) Å, b=8.283(2) Å, c=16.255(3) Å, and β=99.62(3)°. The outstanding feature of the structure is a tetrameric [Te₄O₈(OH)₁₀]^2– anion built up from edge and corner sharing TeO₆ octahedra. These anions and K⁺ cations are held together by electrostatic interactions and by hydrogen bonds. The compound decomposes in two steps at 350 and 420 °C, corresponding to a water and an oxygen loss, respectively, and affording the mixed valence oxide K₂Te^VI₃Te^IVO₁₂.     

Synthesis,crystal structure and properties of a quaternary oxide with a new structure type,BiGaTi4O11

A new quaternary oxide, BiGaTi₄O₁₁ (bismuth gallium tetratitanium undecaoxide), was prepared by heating a mixture of the binary oxides at 1373 K in air. BiGaTi₄O₁₁ melts at 1487 K and prismatic single crystals were obtained from a sample melted at 1523 K and solidified by furnace cooling. The structure of BiGaTi₄O₁₁ was analyzed using single‐crystal X‐ray diffraction to be of a new type that crystallized in the space group Cmcm. A Bi³⁺ site is coordinated by nine O^2? anions, and three oxygen‐coordinated octahedral sites are statistically occupied by Ga³⁺ and Ti⁴⁺ cations. A relative dielectric constant of 46 with a temperature coefficient of 57 ppm K^?1 in the temperature range 297–448 K was measured for a polycrystalline ceramic sample at 150 Hz–1 MHz with a dielectric loss tan δ of less than 0.01. Electrical resistivities measured at 1073 K by alternating‐current impedance spectroscopic and direct‐current methods were 1.16 × 10^?4 and 1.14 × 10^?4 S cm^?1, respectively, which indicates that electrons and/or holes were conduction carriers at high temperature. The optical band gap estimated by the results of diffuse reflectance analysis was 2.9–3.0 eV, while the band gap obtained from the activation energy for electrical conduction was 3.5 eV.     

Synthesis,crystal structures and luminescence properties of europium and terbium picolinamide complexes

The novel coordination structures of europium and terbium chloride-picolinamide complexes （EuCl3-（C6H6N2O）2.5H2O, Eu-pa and TbCl3.（C6H6N2O）2.5H2O, Tb-pa） are reported. The crystal structures in the solid state are characterized by X-ray single crystal diffraction, FTIR, Raman, FIR, THz and luminescence spectroscopy. In the crystal structures, the pyridyl nitrogen and carbonyl oxygen atoms in picolinamide are coordinated to the metal ions to form a five-membered ring structure. The experimental results indicate the similar coordination structures of Eu and Tb-pa complexes and the changes of hydrogen bonds and conformation provide models for the coordination structures of the ligands induced by complexation. The results of lanthanide ions with ligands having amide groups.