Browsing by Author "Lu, KT"

Now showing 1 - 9 of 9
  • No Thumbnail Available
    Item
    Dioxo-vanadium(V), oxo-rhenium(V) and dioxo-uranium(VI) complexes with a tridentate Schiff base ligand
    (Royal Society of Chemistry, 2016-08-03) Zhang, YJ; Fanna, DJ; Shepherd, ND; Karatchevtseva, I; Lu, KT; Kong, L; Price, JR
    The complexation of a julolidine–quinoline based tridentate ligand with three oxo-metal ions, dioxo-vanadium(V), oxo-rhenium(V) and dioxo-uranium(VI), has been investigated with four new complexes being synthesised and structurally characterised. (VO2L)·2/3H2O (1) {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} has a VO2L neutral mononuclear structure with a five-fold coordinated vanadium metal centre in a distorted trigonal bipyramidal geometry. (ReOL2)2(ReCl6)·7DMF (2) [DMF = dimethylformamide] exhibits a mixed valent rhenium complex with a (ReOL2)+ cationic unit in a distorted octahedral metal coordination geometry, charge balanced with (ReCl6)2− anions. [(UO2)L(H2O)2]2·2(NO3)·HL·4H2O (3) and [(UO2)L(CH3OH)2](NO3)·CH3OH (4) both have (UO2L)+ cationic mononuclear structures with either coordinated water or methanol molecules in pentagonal bipyramidal coordination geometries for the uranium metal centres. Intra-/intermolecular interactions including hydrogen bonding and π–π interactions are common and have been discussed. In addition, optical absorption and photoluminescence properties have been investigated. © 2016 The Royal Society of Chemistry
  • No Thumbnail Available
    Item
    Dysprosium complexes with mono-/di-carboxylate ligands—from simple dimers to 2D and 3D frameworks
    (Elsevier, 2014-11-01) Zhang, YJ; Bhadbhade, MM; Scales, N; Karatchevtseva, I; Price, JR; Lu, KT; Lumpkin, GR
    Four dysprosium (Dy) single carboxylates, a formate, a propionate, a butyrate and an oxalate have been synthesized and structurally characterized. The structure of Dy(HCO2)3 (1) contains nine-fold coordinated Dy polyhedra in perfect tricapped trigonal prisms. They are linked through trigonal O atoms forming 1D pillars which are further linked together through tricapped O atoms into a 3D pillared metal organic framework. The network structure is stable up to 360 °C. The structure of [Dy2(C2O4)3(H2O)6]·2.5H2O (2) contains nine-fold coordinated Dy polyhedra linking together through μ2-bridging oxalate anions into a 2D hexagonal layered structure. Both [Dy2(Pr)6(H2O)4]·(HPr)0.5 (3) [Pr=(C2H5CO2)−1] and [Dy2(Bu)6(H2O)4] (4) [Bu=(C3H7CO2)−1] have similar di-nuclear structures. The Raman vibration modes of the complexes have been investigated. © 2016 Elsevier B.V.
  • Thumbnail Image
    Item
    Exploring the influence of pH on the structural intricacies of uranium oxide hydrates containing both Cd(ii) and K(i) ions
    (Royal Society of Chemistry, 2023-05-28) Ablott, TA; Lu, KT; Wei, T; Zhang, YJ
    We report the synthesis of two new dual-cation uranium oxide hydrate (UOH) materials, containing both Cd2+ and K+ ions, along wxrith their characterisation by means of single-crystal X-ray diffraction and a range of other structural and spectroscopic techniques. The materials were found to differ in structures, topology and uranium to cation ratios, with the layered UOH-Cd crystallising in a plate morphology and containing a U : Cd : K ratio of 3 : 1.5 : 1. Conversely, the framework-type UOF-Cd incorporates much less Cd, with a U : Cd : K ratio of 4.4 : 0.2 : 1 and is found as needle-like crystals. A common feature in both structures is the presence of β-U3O8 type layers with a distinct uranium centre which lacks the expected uranyl bonds, highlighting the importance of the β-U3O8 layer in the subsequent self-assembly and preferential formation of a variety of structural types. Most importantly, by exploiting the additional flexibility provided by monovalent cation species (i.e., K+) as secondary metal cations to synthesise these novel dual-cation materials, this work highlights the potential for broadening the scope of viable synthetic UOH phases towards furthering the understanding of these systems in their roles as alteration products in the surrounds of spent nuclear fuel in deep geological repositories. © The Authors - Open Access CC BY Licence
  • No Thumbnail Available
    Item
    Hydrothermal synthesis, structures and properties of two uranyl oxide hydroxyl hydrate phases with Co(II) or Ni(II) ions
    (Royal Society of Chemistry., 2016-04-11) Zhang, YJ; Čejka, J; Lumpkin, GR; Tran, TT; Aharonovich, I; Karatchevtseva, I; Price, JR; Scales, N; Lu, KT
    Two new iso-structured uranyl oxide hydroxyl hydrate (UOH) phases with the incorporation of cobalt(II) or nickel(II) ions have been synthesised under hydrothermal conditions and structurally characterised. Both K4Co(OH)3(H2O)9[(UO2)12(O)7(OH)13] (1) and K4Ni(OH)3(H2O)9[(UO2)12(O)7(OH)13] (2) have two-dimensional (2D) polymeric uranyl oxohydroxyl layers with either potassium and hydroxyl cobalt(II) (1) or potassium and hydroxyl nickel(II) (2) ions between layers via uranyl–cation interactions. This work highlights the feasibility of making new UOH phases via a hydrothermal route at relatively higher solution pHs. It also demonstrates that other transition metal ions which are readily available in the environment may also be incorporated into such UOH phases during the natural weathering of uraninite as well as during the storage and disposal of spent nuclear fuels. © 2016 The Royal Society of Chemistry
  • Thumbnail Image
    Item
    An investigation of LnUO4 (Ln = Dy and Ho): structures, microstructures, uranium valences and magnetic properties
    (Elsevier, 2021-09-12) Lu, KT; Zhang, YJ; Wei, T; Zhang, ZM; Avdeev, M; Zheng, RK
    The phase formation, structures, microstructures, uranium valences and magnetic properties of LnUO4 (Ln = Dy and Ho) were investigated. Although sintering of the precursors in argon at 1450 °C for seven days and 1400 °C for six hours both resulted in the desired phase, sintering at higher temperature for longer duration led to the formations of well crystalized lanthanide monouranates with much better homogeneity. Cubic fluorite structures were determined using X-ray diffraction data, which was confirmed with transmission electron microscopy and Raman spectroscopy. The nature of pentavalent uranium was verified with a combination of diffuse reflectance and X-ray photoelectron spectroscopies. The magnetic suseptability measurements revealed that they are paramagnetic with no long-range magnetic orders, likely due to the extensive short-range oxygen defects. Overall the improved structural and spectroscopic understandings of LnUO4 have implications in nuclear materials especially for potential accident tolerance fuels and spent fuel management. Crown Copyright © 2021 Published by Elsevier Ltd.
  • Thumbnail Image
    Item
    Lanthanide mononuclear complexes with a tridentate Schiff base ligand: structures, spectroscopies and properties
    (Elsevier, 2019-03-21) Zhang, YJ; Avdeev, M; Price, JR; Karatchevtseva, I; Fanna, DJ; Chironi, I; Lu, KT
    A series of six lanthanide mononuclear complexes with a julolidine-quinoline based tridentate Schiff base ligand have been synthesized and structurally characterized. The complexes [NdL2(CH3OH)(NO3)]·CH3OH (1) and [LnL2(NO3)] [Ln = Eu (2), Gd (3), Dy (4), Ho (5), Lu (6)] {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} all have mononuclear structures with a metal to ligand ratio of 1:2. The Ln(III) ions are nine-fold coordinated by two tridentate Schiff base ligands and a bidentate nitrate anion except for complex 1 in which Nd(III) ion is ten-fold coordinated with an additional MeOH molecule. The coordination of a bidentate nitrate anion makes chirality to the complexes with equal enantiomers presence in the solid state. Lanthanide contraction has been observed with the average Ln–O/Ln–N bond lengths decreasing along the lanthanide series. Vibrational modes (2–5), electronic structures (1–3), thermal stability (2) and magnetic properties (3) have been further investigated and reported. Crown Copyright © 2019 Published by Elsevier Ltd.
  • No Thumbnail Available
    Item
    Microstructural evolution of an ion irradiated Ni–Mo–Cr–Fe alloy at elevated temperatures
    (Materials Transactions, 2014-01-01) de los Reyes, M; Edwards, L; Kirk, MA; Bhattacharyya, D; Lu, KT; Lumpkin, GR
    The irradiation behavior of a Ni–Mo–Cr–Fe alloy, of the type currently being considered for use in future molten salt cooled reactors, has been investigated in situ using 1 MeV Kr ions at temperatures of 723 and 973 K. When irradiated to 5 dpa, experimental observations reveal the instantaneous formation and annihilation of point defect clusters, with such processes attributed to the long range elastic interactions that occur between defects through multiple intra-cascade overlap. Corresponding differences in the defect cluster density and size distribution suggest that changes to the microstructure were dependent upon temperature and dose, affecting the growth, accumulation and mobility of irradiation-induced defect clusters under these conditions. © 2014,The Japan Institute of Metals and Materials.
  • No Thumbnail Available
    Item
    Solvothermal synthesis of uranium(VI) phases with aromatic carboxylate ligands: a dinuclear complex with 4-hydroxybenzoic acid and a 3D framework with terephthalic acid
    (Elsevier B.V., 2016-02-01) Zhang, YJ; Karatchevtseva, I; Bhadbhade, MM; Tran, TT; Aharonovich, I; Fanna, DJ; Shepherd, ND; Lu, KT; Li, F; Lumpkin, GR
    With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H2phb) or terephthalic acid (H2tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO2)2(Hphb)2(phb)(DMF)(H2O)3]·4H2O (1) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ2-bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO2)(tph)(DMF)] (2) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ4-terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1, and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been investigated. © 2015 Elsevier Inc.
  • No Thumbnail Available
    Item
    Uranium(VI) hybrid materials with [(UO2)3(µ3‐O)(µ2‐OH)3]+ as the sub–building unit via uranyl–cation interactions
    (John Wiley and Sons, 2016-01-14) Zhang, YJ; Clegg, JK; Lu, KT; Lumpkin, GR; Tran, TT; Aharonovich, I; Scales, N; Li, F
    The hydrothermal reaction of uranyl nitrate with 1,4-benzenedicarboxylic acid (H2bdc) in the presence of strontium or potassium hydroxides and nitrates afford the formation of two new uranyl hybrid materials featuring extensive uranyl-strontium or uranyl-potassium interactions with [(UO2)3(µ3-O)(µ2-OH)3]+ as the sub-building unit. Sr1.5[(UO2)12(O)3(OH)13(bdc)4]⋅6H2O (1) contains one-dimensional (1D) uranyl oxohydroxyl ribbons made of trinuclear pentagonal bipyramidal uranyl units. The ribbons are linked together via uranyl-strontium interactions to form 2D inorganic domains which are further connected through µ4-bdc anions forming a 3D hybrid structure. This is the first reported uranyl-strontium interaction in extended hybrid solid with the shortest Sr-O−yl bond length of 2.596 (8) Å. K3[(UO2)12(O)3(OH)13(bdc)4]⋅8H2O (2) has a similar 3D hybrid structure built up through extensive K-O−yl interactions with the shortest K-O−yl bond length of 2.620 (6) Å. Raman spectroscopy has confirmed the presence of oxo-bridging (U−O−U) vibrations. Thermal stabilities and photoluminescent properties are reported. © 2016 Wiley‐VCH Verlag GmbH & Co.