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Instruments / Technical Area	Publication Details	Published
	Highly anisotropic thermal transport in LiCoO2 Hui Yang , Jia-yue Yang , Christopher N. Savory , Jonathan M. Skelton , Benjamin J. Morgan , David O. Scanlon , Aron Walsh The Journal Of Physical Chemistry Letters DOI: 10.1021/acs.jpclett.9b02073 Show Abstract ▼ Abstract: LiCoO2 is the prototypical cathode in lithium-ion batteries. Its crystal structure consists of Li+ and CoO2– layers that alternate along the hexagonal ⟨0001⟩ axis. It is well established that the ionic and electronic conduction are anisotropic, but little is known regarding the heat transport. We analyze the phonon dispersion and lifetimes using anharmonic lattice dynamics based on quantum-chemical force constants. Around room temperature, the thermal conductivity in the hexagonal ab plane of the layered cathode is ∼6 times higher than that along the c axis. An upper limit to the average thermal conductivity at T = 300 K of 38.5 W m–1 K–1 is set by short phonon lifetimes associated with anharmonic interactions within the octahedral face-sharing CoO2– network. Observations of conductivity <10 W m–1 K–1 can be understood by additional scattering channels including grain boundaries in polycrystalline samples. The impact on thermal processes in lithium-ion batteries is discussed.	Sep 2019
I19-Small Molecule Single Crystal Diffraction	Monitoring Photo-induced Population Dynamics in Metastable Linkage Isomer Crystals: A Crystallographic Kinetic Study of [Pd(Bu4dien)NO2]BPh4 Lauren E. Hatcher , Jonathan M. Skelton , Mark R. Warren , Clare Stubbs , Estelina Lora Da Silva , Paul R. Raithby Physical Chemistry Chemical Physics DOI: 10.1039/C7CP05422J Diamond Proposal Number(s): [8567, 9734, 13698] Open Access Show Abstract ▼ Abstract: We present a detailed kinetic study of photo-induced solid state linkage isomerism in the compound [Pd(Bu4dien)NO2]BPh4 (Bu4dien = N,N,N’,N’-tetrabutyldiethylenetriamine) using in-situ photocrystallographic techniques. We explore the key variables that influence the photoconversion and develop a detailed kinetic model for the excitation and decay processes and the temperature dependence of the conversion rates. We show that by varying the temperature the lifetime of the excited state can be varied over orders of magnitude, making these systems ideal test cases for the development of new time-resolved X-ray diffraction methods. The kinetic model is used to build a numerical-simulation tool, which we use to explore the practicalities of pump-probe single-crystal diffraction experiments with minute and second time-resolution.	Jan 2018
I24-Microfocus Macromolecular Crystallography	A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor M. J. Bryant , J. M. Skelton , L. E. Hatcher , C. Stubbs , E. Madrid , A. R. Pallipurath , L. H. Thomas , Ch. H. Woodall , J. Christensen , S. Fuertes , T. P. Robinson , C. M. Beavers , S. J. Teat , M. Warren , F. Pradaux-caggiano , A. Walsh , F. Marken , D. R. Carbery , S. C. Parker , N. B. Mckeown , R. Malpass-evans , M. Carta , P. R. Raithby Nature Communications 8 DOI: 10.1038/s41467-017-01941-2 Open Access Show Abstract ▼ Abstract: Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses.	Dec 2017
I19-Small Molecule Single Crystal Diffraction	Observation of a re-entrant phase transition in the molecular complex tris(μ 2 -3,5-diisopropyl-1,2,4-triazolato-κ 2 N 1 : N 2 )trigold(I) under high pressure Christopher H. Woodall , Jeppe Christensen , Jonathan M. Skelton , Lauren E. Hatcher , Andrew Parlett , Paul R. Raithby , Aron Walsh , Stephen C. Parker , Christine M. Beavers , Simon J. Teat , Mourad Intissar , Christian Reber , David R. Allan Iucrj 3, 367 - 376 DOI: 10.1107/S2052252516013129 Open Access Show Abstract ▼ Abstract: We report a molecular crystal that exhibits four successive phase transitions under hydrostatic pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ2-3,5-diisopropyl-1,2,4-triazolato-κ2N1:N2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P21/n phase above 1 GPa, followed by a P21/a phase above 2 GPa and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P21/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P21/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm−1 at 2.40 GPa, decreasing steeply to 13550 cm−1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.	Sep 2016
I19-Small Molecule Single Crystal Diffraction	Sulfamerazine: Understanding the Influence of Slip Planes in the Polymorphic Phase Transformation through X-Ray Crystallographic Studies and ab Initio Lattice Dynamics Anuradha R. Pallipurath , Jonathan M. Skelton , Mark R. Warren , Naghmeh Kamali , Patrick Mcardle , Andrea Erxleben Molecular Pharmaceutics 12 (10), 3735 - 3748 DOI: 10.1021/acs.molpharmaceut.5b00504 PMID: 26317333 Show Abstract ▼ Abstract: Understanding the polymorphism exhibited by organic active-pharmaceutical ingredients (APIs), in particular the relationships between crystal structure and the thermodynamics of polymorph stability, is vital for the production of more stable drugs and better therapeutics, and for the economics of the pharmaceutical industry in general. In this article, we report a detailed study of the structure–property relationships among the polymorphs of the model API, Sulfamerazine. Detailed experimental characterization using synchrotron radiation is complemented by computational modeling of the lattice dynamics and mechanical properties, in order to study the origin of differences in millability and to investigate the thermodynamics of the phase equilibria. Good agreement is observed between the simulated phonon spectra and mid-infrared and Raman spectra. The presence of slip planes, which are found to give rise to low-frequency lattice vibrations, explains the higher millability of Form I compared to Form II. Energy/volume curves for the three polymorphs, together with the temperature dependence of the thermodynamic free energy computed from the phonon frequencies, explains why Form II converts to Form I at high temperature, whereas Form III is a rare polymorph that is difficult to isolate. The combined experimental and theoretical approach employed here should be generally applicable to the study of other systems that exhibit polymorphism.	Oct 2015

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