ABSTRACT
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 850â °C, were investigated. Although with a full Eu3+ concentration (9.96 × 1021â ionsâ 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 (393â nm), the series of samples shows the characteristic emissions of Eu3+ ions in the visible region from 575 to 715â nm. The sample sintered at 800â °C gives the strongest emission and its lifetime sintered at 800â °C (1.88â ms) is also the longest of all.
ABSTRACT
A series of orthophosphates Na3Ln(PO4)2 (Ln = lanthanoids) have for a long time been known as good luminescent materials, yet their crystal structures have not been studied in full detail. In this work, compound Na3La(PO4)2 was prepared using molten salt (flux) method and for the first time was structurally determined on X-ray single-crystal diffraction data. Interestingly, it crystallizes in the four-dimensional incommensurately modulated structure with orthorhombic superspace group Pca21(0ß0)000 and modulation wave vector q = 0.387b*. Furthermore, to evaluate the potentiality of Na3La(PO4)2 to be used as a luminescent host material, 5 mol % Eu3+, Tb3+, and Dy3+ doped phosphors were prepared, respectively. The excitation spectra, emission spectra, decay time, quantum efficiency, and the color purity of prepared phosphors, Na3La0.95Eu0.05(PO4)2, Na3La0.95Tb0.05(PO4)2, and Na3La0.95Dy0.05(PO4)2, were studied.
ABSTRACT
Caesium aluminium dizirconium tetrakis[phosphate(V)], CsAlZr(2)(PO(4))(4), has been synthesized by high-temperature reaction and studied by single-crystal X-ray diffraction at room temperature. This represents the first detailed structural analysis of an anhydrous phosphate containing both zirconium and aluminium. The structure features a complicated three-dimensional framework of [AlZr(2)(PO(4))(4)] constructed by PO(4), AlO(4) and ZrO(6) polyhedra interconnected via corner-sharing O atoms, and one-dimensional Cs chains which are located in the infinite tunnels within the [AlZr(2)(PO(4))(4)] framework, which run along the c axis. The Cs, Al, one P and two O atoms lie on a mirror plane, while a second P atom lies on a twofold axis.
ABSTRACT
The novel hydrothermally synthesized title compound, pentabarium tetrachloride octahydrate octakis(oxovanadium phosphate), Ba(5)Cl(4)(H(2)O)(8)(VPO(5))(8), crystallizes in the orthorhombic space group Cmca with a unit cell containing four formula units. Two Ba(2+) cations, two Cl(-) anions and the O atoms of four water molecules are situated on the (100) mirror plane, while the third independent Ba(2+) cation is on the intersection of the (100) plane and the twofold axis parallel to a. Two phosphate P atoms are on twofold axes, while the remaining independent P atom and both V atoms are in general positions. The structure is characterized by two kinds of layers, namely anionic oxovanadium phosphate (VPO(5)), composed of corner-sharing VO(5) square pyramids and PO(4) tetrahedra, and cationic barium chloride hydrate clusters, Ba(5)Cl(4)(H(2)O)(8), composed of three Ba(2+) cations linked by bridging chloride anions. The layers are connected by Ba-O bonds to generate a three-dimensional structure.
ABSTRACT
In the title complex, [Zn(NO(3))(2)(C(17)H(14)N(2)O(2))(H(2)O)], the six-coordinated Zn atom is in a distorted octa-hedral geometry, the donor centers being two O atoms and one N atom from the tridentate organic ligand, a water O atom and two O atoms from two monodentate nitrate ions. In the crystal, O-Hâ¯O hydrogen bonds between the coordinated water mol-ecules and nitrate O atoms and N-Hâ¯O hydrogen bonds between the main ligand and nitrate O atoms consolidate the three-dimensional network.
ABSTRACT
In the title complex, [CuCl(2)(C(18)H(16)N(2)O(2))(2)]·CH(3)CN·H(2)O, the six-coordinated Cu atom is in a distorted octa-hedral geometry with the donor centers of two O atoms and two N atom from two bidentate ligands, and two chloride ions. In the crystal, pairs of inter-molecular N-H⯠Cl hydrogen bonds form centrosymmetric dimers and inter-molecular O-H⯠O hydrogen bonds between the ligand and the uncoordinated water mol-ecules link the dimers into chains parallel to the c axis.
ABSTRACT
In the title compound, C(16)H(10)O(8)·H(2)O, the dihedral angle between the two benzene rings is 71.63â (5)°. In the crystal structure, pairs of inversion-related mol-ecules are stacked [mean inter-planar spacing = 3.5195â (18)â Å], and O-Hâ¯O and C-Hâ¯O hydrogen bonds create a three-dimensional network.
ABSTRACT
In the title compound, C(13)H(14)N(4)O·C(3)H(7)NO, a 1,5-phenyl-carbonohydrazide mol-ecule cocrystallizes with an N,N-dimethyl-formamide mol-ecule. In the 1,5-phenyl-carbonohydrazide mol-ecule, the two phenyl rings are twisted by an angle of 45.8â (5)°. Inter-molecular N-Hâ¯O hydrogen bonds and weak inter-molecular C-Hâ¯O inter-actions contribute to a supra-molecular two-dimensional network in the (101) plane.
