Philip Lightfoot

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Organization: University of St Andrews , England

Department: School of Chemistry

Title: Professor(PhD)

TOPICS

Material Chemistry

Analytical Chemistry

solid state nmr

Chemicals
References

Reinvestigation of Na2Fe2(C2O4)3·2H2O: An Iron-Based Positive Electrode for Secondary Batteries

Co-reporter:Wenjiao Yao, Moulay-Tahar Sougrati, Khang Hoang, Jianing Hui, Philip Lightfoot, and A. Robert Armstrong

Chemistry of Materials November 14, 2017 Volume 29(Issue 21) pp:9095-9095

Publication Date(Web):October 4, 2017

DOI:10.1021/acs.chemmater.7b02764

We have reinvestigated the polyanionic compound Na2Fe2(C2O4)3·2H2O, previously reported to be electrochemically inactive in lithium-ion batteries (LIBs), as a positive electrode for sodium-ion batteries (NIBs). The present study demonstrates that it is capable of delivering a reversible capacity close to its theoretical value (117 mA h g–1) with three redox plateaus at 2.9, 3.3, and 3.6 V versus Na/Na+ in the potential range 1.7–4.2 V. The obtained energy density of 326 W h kg–1 is among the highest of all reported polyanionic cathodes in NIBs. The origin of the electrochemical activity can be traced back to the electronic structure of the compound and the low migration energy barrier of the alkali ion observed in first-principles density-functional theory calculations.

Na2Fe(C2O4)F2: A New Iron-Based Polyoxyanion Cathode for Li/Na Ion Batteries

Co-reporter:Wenjiao Yao, Moulay-Tahar Sougrati, Khang Hoang, Jianing Hui, Philip Lightfoot, and A. Robert Armstrong

Chemistry of Materials March 14, 2017 Volume 29(Issue 5) pp:2167-2167

Publication Date(Web):February 10, 2017

DOI:10.1021/acs.chemmater.6b04859

A new mixed anion compound, Na2Fe(C2O4)F2, has been prepared by hydrothermal synthesis. The crystal structure exhibits infinite chains of corner-linked FeII-centered octahedra, with coordination composed of both oxalate and fluoride ligands. This compound exhibits promising reversible lithium and sodium insertion. On extended cycling, Na2Fe(C2O4)F2 is capable of reversibly inserting 0.67 Li+ or 0.56 Na+ per formula unit up to 50 cycles at the average discharge voltages of 3.3 and 3.0 V, respectively. This represents arguably the best performance as a prospective cathode material so far observed among oxalates and is comparable to many known iron phosphate-based cathode materials.

Diverse Family of Layered Frustrated Magnets with Tailorable Interlayer Interactions

Co-reporter:Wenjiao Yao, Lucy Clark, Mingjun Xia, Teng Li, Stephen L. Lee, and Philip Lightfoot

Chemistry of Materials August 22, 2017 Volume 29(Issue 16) pp:6616-6616

Publication Date(Web):July 27, 2017

DOI:10.1021/acs.chemmater.7b02434

Crystal structure of guanidinium hexafluoridovanadate(III), (CN3H6)3[VF6]: an unusual hybrid compound related to perovskite

Co-reporter:Cameron Black

Acta Crystallographica Section C 2017 Volume 73(Issue 3) pp:244-246

Publication Date(Web):

DOI:10.1107/S2053229617001711

Vanadium fluorides with novel crystal–chemical features and interesting physical properties can be prepared by solvothermal synthetic routes. The title compound, guanidinium hexafluoridovanadate(III), has a cubic structure (space group Pa), exhibiting isolated regular VF6 octahedral units, which are hydrogen bonded to protonated guanidinium moieties. Although the VF6 octahedral units are not linked directly together, there are structural similarities between this crystal structure and those of the wider family of perovskite materials, in particular, hybrid perovskites based on extended ligands such as cyanide. In this context, the octahedral tilt system of the present compound is of interest and demonstrates that unusual tilt systems can be mediated via `molecular' linkers which allow only supramolecular rather than covalent interactions.

NaFe3(HPO3)2((H,F)PO2OH)6: A Potential Cathode Material and a Novel Ferrimagnet

Co-reporter:Irene Munaò, Elena A. Zvereva, Olga S. Volkova, Alexander N. Vasiliev, A. Robert Armstrong, and Philip Lightfoot

Inorganic Chemistry 2016 Volume 55(Issue 5) pp:2558-2564

Publication Date(Web):February 16, 2016

DOI:10.1021/acs.inorgchem.5b02922

A novel iron fluorophosphite, NaFe3(HPO3)2((H,F)PO2OH)6, was synthesized by a dry low-temperature synthesis route. The phase was shown to be electrochemically active for reversible insertion of Na+ ions, with an average discharge voltage of 2.5 V and an experimental capacity at low rates of up to 90 mAhg−1. Simple synthesis, low-cost materials, excellent capacity retention, and efficiency suggest this class of material is competitive with similar oxyanion-based compounds as a cathode material for Na batteries. The characterization of physical properties by means of magnetization, specific heat, and electron spin resonance measurements confirms the presence of two magnetically nonequivalent Fe3+ sites. The compound orders magnetically at TC ≈ 9.4 K into a state with spontaneous magnetization.

V2O2F4(H2O)2H2O: a new V4+ layer structure related to VOF3

Co-reporter:Cameron Black

Acta Crystallographica Section C 2016 Volume 72( Issue 1) pp:80-83

Publication Date(Web):

DOI:10.1107/S2053229615024122

V^IV oxyfluorides are of interest as frustrated magnets. The successful synthesis of two-dimensionally connected vanadium(IV) oxyfluoride structures generally requires the use of ionic liquids as solvents. During solvothermal synthesis experiments aimed at producing two- and three-dimensional vanadium(IV) selenites with triangular lattices, the title compound, diaquatetra-μ-fluorido-dioxidodivanadium(IV) monohydrate, V₂O₂F₄(H₂O)₂·H₂O, was discovered and features a new infinite V⁴⁺-containing two-dimensional layer comprised of fluorine-bridged corner- and edge-sharing VOF₄(H₂O) octahedral building units. The synthesis was carried out under solvothermal conditions. The V⁴⁺ centre exhibits a typical off-centring, with a short V=O bond and an elongated trans-V—F bond. Hydrogen-bonded water molecules occur between the layers. The structure is related to previously reported vanadium oxyfluoride structures, in particular, the same layer topology is seen in VOF₃.

Extending the Family of V4+ S= Kagome Antiferromagnets

Co-reporter:Dr. Lucy Clark;Dr. Farida H. Aidoudi;Dr. Cameron Black;Dr. Kasun S. A. Arachchige;Dr. Alexra M. Z. Slawin;Dr. Russell E. Morris ;Dr. Philip Lightfoot

Angewandte Chemie 2015 Volume 127( Issue 51) pp:

Publication Date(Web):

DOI:10.1002/ange.201506869

Abstract

The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C₃H₅N₂][V₉O₆F₂₄(H₂O)₂] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V⁴⁺ S= ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V⁴⁺, means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long-range magnetic order down to 2 K despite considerable antiferromagnetic exchange.

Extending the Family of V4+ S= Kagome Antiferromagnets

Co-reporter:Dr. Lucy Clark;Dr. Farida H. Aidoudi;Dr. Cameron Black;Dr. Kasun S. A. Arachchige;Dr. Alexra M. Z. Slawin;Dr. Russell E. Morris ;Dr. Philip Lightfoot

Angewandte Chemie International Edition 2015 Volume 54( Issue 51) pp:

Publication Date(Web):

DOI:10.1002/anie.201506869

Abstract

Re-entrant structural phase transition in a frustrated kagome magnet, Rb2SnCu3F12

Co-reporter:Lewis J. Downie, Stephen P. Thompson, Chiu C. Tang, Simon Parsons and Philip Lightfoot

CrystEngComm 2013 vol. 15(Issue 37) pp:7426-7429

Publication Date(Web):14 Aug 2013

DOI:10.1039/C3CE41422A

Rb2SnCu3F12 has been studied using synchrotron powder X-ray diffraction, powder neutron diffraction and single crystal X-ray diffraction at a range of temperatures (100–500 K). A broad but clear phase transition, possibly of re-entrant character, is found to occur in the powder form, whereas the corresponding transition is not seen in the single crystal.

Structural Study of La1–xYxScO3, Combining Neutron Diffraction, Solid-State NMR, and First-Principles DFT Calculations

Co-reporter:Karen E. Johnston, Martin R. Mitchell, Frédéric Blanc, Philip Lightfoot, and Sharon E. Ashbrook

The Journal of Physical Chemistry C 2013 Volume 117(Issue 5) pp:2252-2265

Publication Date(Web):January 14, 2013

DOI:10.1021/jp310878b

The solid solution La1–xYxScO3 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) has been successfully synthesized using conventional solid-state techniques. Detailed structural characterization has been undertaken using high-resolution neutron powder diffraction and multinuclear (45Sc, 139La, 89Y, and 17O) solid-state NMR and is supported by first-principles density functional theory calculations. Diffraction data indicate that a reduction in both the unit cell parameters and unit cell volume is observed with increasing x, and an orthorhombic perovskite structure (space group Pbnm) is retained across the series. 45Sc multiple-quantum (MQ) MAS NMR spectra proved to be highly sensitive to subtle structural changes and, in particular, cation substitutions. NMR spectra of La1–xYxScO3 exhibited significant broadening, resulting from distributions of both quadrupolar and chemical shift parameters, owing to the disordered nature of the material. In contrast to previous single-crystal studies, which reveal small deficiencies at both the lanthanide and oxygen sites, the powder samples studied herein are found to be stoichiometric.

Solvothermal indium fluoride chemistry: Syntheses and crystal structures of K5In3F14, β-(NH4)3InF6 and [NH4]3[C6H21N4]2[In4F21]

Co-reporter:Anil C.A. Jayasundera, Richard J. Goff, Yang Li, Adrian A. Finch, Philip Lightfoot

Journal of Solid State Chemistry 2010 Volume 183(Issue 2) pp:356-360

Publication Date(Web):February 2010

DOI:10.1016/j.jssc.2009.11.022

The solvothermal syntheses and crystal structures of three indium fluorides are presented. K5In3F14 (1) and β-(NH4)3InF6 (2) are variants on known inorganic structure types chiolite and cryolite, respectively, with the latter exhibiting a complex and apparently novel structural distortion. [NH4]3[C6H21N4]2[In4F21] (3) represents a new hybrid composition displaying a unique trimeric metal fluoride building unit.Solvothermal synthesis has been used to prepare three indium fluorides, including a novel hybrid material containing a unique [In3F15] trimer templated by tren.

Solvothermal Synthesis and Luminescent Properties of Two Organically Templated Chain-Structure Fluorides, [C4H14N2][MF5] (M = In, Sc)

Co-reporter:Anil C. A. Jayasundera, Adrian A. Finch, Philip Wormald and Philip Lightfoot

Chemistry of Materials 2008 Volume 20(Issue 21) pp:6810

Publication Date(Web):October 14, 2008

DOI:10.1021/cm802049d

The solvothermal syntheses and crystal structures of organically templated indium fluoride, [C4H14N2][InF5] 1, and its scandium analogue, [C4H14N2][ScF5] 2, are reported. Compound 1 represents the first indium fluoride with extended inorganic connectivity prepared using an organic amine, 1,4-diaminobutane (DAB), as a structure-directing agent. 1 is orthorhombic, space group Ibam, with cell parameters a = 9.324(2) Å, b = 11.391(2) Å, c = 8.401(2), and Z = 4 (for isostructural 2: a = 9.353(3) Å, b = 11.433 (1) Å, c = 8.226 (4) Å). The structure of 1 consists of infinite trans vertex sharing (InF5)∞ chains running parallel to the c-axis, which are linked via H-bonded organic moieties. The photoluminescence properties of the doped compounds, of nominal composition [C4H14N2][In1-xLnxF5] (Ln=Tb and/or Eu), have been explored. For x = 0.05 Eu3+, 1 exhibits a dominant orange emission at 592.5 nm from the 5D0 → 7F1 magnetic dipole transition within Eu3+. For x = 0.08 Tb3+, 1 shows strong down-conversion fluorescence corresponding to 5D4 → 7F5 (green at 543.5 nm). In addition, a Tb3+/Eu3+ co-doped sample exhibits a combination of green (Tb3+) and orange (Eu3+) luminescence, with Tb3+ enhancing the emission of Eu3+ in this host. The dependence of luminescence intensity on dopant concentration for 1 has been analyzed. The scandium and fluorine local environments in 2 have been characterized by 19F and 45Sc solid-state magic-angle spinning (MAS) NMR, which confirms a single scandium site together with discrete bridging and planar fluorine sites.

On the crystal structures of SrTeO3

Co-reporter:Oleg A. Dityatiev, Petr S. Berdonosov, Valery A. Dolgikh, David W. Aldous, Philip Lightfoot

Solid State Sciences 2006 Volume 8(Issue 7) pp:830-835

Publication Date(Web):July 2006

DOI:10.1016/j.solidstatesciences.2006.03.003

SrTeO3 has been studied by powder neutron diffraction (PND) experiments and by second harmonic generation (SHG) method at a series of temperatures between 20 and 560 °C. The SrTeO3 low temperature (22 °C) form was found (Rwp=1.49%Rwp=1.49%, χ2=1.06χ2=1.06) to crystallize in space group C2/c with the unit cell parameters a=28.133(9) Åa=28.133(9) Å, b=5.9044(15) Åb=5.9044(15) Å, c=28.418(6) Åc=28.418(6) Å, β=114.303(17)°β=114.303(17)°. The Sr atoms are coordinated by six, seven or eight oxygen atoms. Each Te atom has a similar ‘pyramidal’ geometry, coordinated by three oxygen atoms having similar TeO bond lengths. The Te4+ lone-pair (E) plays an active stereochemical role. The SrO polyhedra form an openwork framework with 2 types of channels. Inside the channels the tellurium atoms are located. The TeO3E pyramids do not connect to each other; instead they share their oxygen atoms with Sr polyhedra. The discontinuous change of the SrTeO3 lattice parameters in the region 260–310 °C and abrupt growth of SHG signal in this temperature region correspond to the onset of the ferroelectric phase in a first-order phase transition. However from the diffraction data acquired at 410 °C no evidence of lowering of the symmetry was found. The structure model of the SrTeO3 high temperature (410 °C) modification is proposed in the same space group C2/c. The plausible reasons of the discrepancy between the PND and SHG results are discussed.

A novel family of layered bismuth compounds II: the crystal structures of Pb0.6Bi1.4Rb0.6O2Z2, Z=Cl, Br, and I

Co-reporter:Dmitri O Charkin, Oleg A Dytyatiev, Valeri A Dolgikh, Philip Lightfoot

Journal of Solid State Chemistry 2003 Volume 173(Issue 1) pp:83-90

Publication Date(Web):June 2003

DOI:10.1016/S0022-4596(03)00094-X

Using various synthetic approaches, we have prepared over 50 new multinary bismuth oxyhalides which crystallize in four layered structure types. Most of the compounds belong to the three previously reported structure types involving fluorite- and CsCl-like metal–oxygen vs. metal–halogen layers as well as single or double halide ion sheets. The majority of Bi2−xAxQ0.6O2Z2 (A=Li, Na, K, Ca, Sr, Ba, Pb; Q=Rb, Cs; Z=Cl, Br, I) compounds crystallize in the tetragonal structure of Pb0.6Bi1.4Cs0.6O2Cl2 (Y2) while both Bi1.4Ba0.6Q0.6O2I2 (Q=Rb, Cs) oxyiodides adopt its orthorhombically distorted, partially ordered version. Due to the lower degree of substitution, the fluorite-like layers in the Y2 structure accommodate more A cations than previously known for related Bi compounds. However, very large Tl+ or Rb+ give compounds with another, as yet unknown, structure. We discuss the influence of size and charge of A cations and stoichiometry of [Bi2−xAxO2] fluorite layers on structure and stability of layered oxyhalides of bismuth. Also, we predict formation of isostructural compounds with smaller Q cations like Tl+ and K+.

Synthesis and structure of three manganese oxalates: MnC2O4·2H2O, [C4H8(NH2)2][Mn2(C2O4)3] and Mn2(C2O4)(OH)2

Co-reporter:Zoe A.D. Lethbridge, Aileen F. Congreve, Emma Esslemont, Alexandra M.Z. Slawin, Philip Lightfoot

Journal of Solid State Chemistry 2003 Volume 172(Issue 1) pp:212-218

Publication Date(Web):April 2003

DOI:10.1016/S0022-4596(03)00035-5

Three manganese oxalates have been hydrothermally synthesized, and their structures determined by single-crystal X-ray diffraction. MnC2O4·2H2O (I) is orthorhombic, P212121, , , , , Z=4, final R, Rw=0.0832, 0.1017 for 561 observed data (I>3σ(I)). The one-dimensional structure consists of chains of oxalate-bridged manganese centers. [C4H8(NH2)2][Mn2(C2O4)3] (II) is triclinic, , , , , α=81.489(2)°, β=81.045(2)°, γ=86.076(2)°, , Z=1, final R, Rw=0.0467, 0.0596 for 1773 observed data (I > 3σ (I)). The three-dimensional framework is constructed from seven coordinate manganese and oxalate anions. The material contains extra-framework diprotonated piperazine cations. Mn2(C2O4)(OH)2 (III) is monoclinic, P21/c, , , , β=91.10(3)°, , Z=1, final R1, wR2=0.0710, 0.1378 for 268 observed data (I>2σ (I)). The structure is also three dimensional, with layers of MnO6 octahedra pillared by oxalate anions. The hydroxide group is found bonded to three manganese centers resulting in a four coordinate oxygen.

Synthesis, structural relationships and magnetic properties of new amine-templated manganese(II) phosphate oxalate framework materials

Co-reporter:Zoe A. D. Lethbridge, Satish K. Tiwary, Andrew Harrison and Philip Lightfoot

Dalton Transactions 2001 (Issue 12) pp:1904-1910

Publication Date(Web):29 May 2001

DOI:10.1039/B101005K

Three novel three-dimensional framework materials in the manganese(II)–phosphate–oxalate system have been prepared hydrothermally using organic amines as structure-directing agents. [H3NC6H10NH3][Mn2(HPO4)2(C2O4)(H2O)2] 1 and [H3N(CH2)2NH3][Mn2(HPO4)2(C2O4)(H2O)2] 2 have related, but not isomorphous, structures based on layers of vertex-sharing MnO6 and PO4 polyhedra linked by bridging oxalate groups. [H3N(CH2)2NH3][Mn4(HPO4)2(C2O4)3(H2O)2]·2H2O 3 has a very different structure composed of edge-sharing dimeric MnO6 units linked into chains by PO4 groups, and into a 3-D framework by oxalate units. 3 can be topotactically dehydrated, with loss of both extra-framework and co-ordinated water, to produce a new phase 4. The magnetic susceptibilities of phases 1, 3 and 4 all show Curie–Weiss behaviour above about 50 K, and a maximum in the susceptibility curve in the vicinity of 7–12 K, indicating significant antiferromagnetic exchange. Structural relationships to other phosphate–oxalate frameworks are discussed.