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Dive into the research topics where Duncan J. Francis is active.

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Featured researches published by Duncan J. Francis.


Journal of Applied Crystallography | 2002

Attainment of near-hydrostatic compression conditions using the Paris–Edinburgh cell

William G. Marshall; Duncan J. Francis

By means of a straightforward modification to the Paris–Edinburgh cell gasket configuration, it is now possible to utilize fluid pressure-transmitting media up to at least 9 GPa. Test data on various representative samples are presented, discussed and contrasted with typical results obtained using the earlier gasket arrangement and Fluorinert pressure-transmitting medium. For the case of deuterated urea, the significant improvement in compression conditions revealed the existence of two new structural phases (IV and V) which are first observed at 3.0 GPa and 7.5 GPa. Future development possibilities for the technique of sample encapsulation are presented and discussed.


Chemical Communications | 2010

Pressure-cooking of explosives-the crystal structure of epsilon-RDX as determined by X-ray and neutron diffraction

David I. A. Millar; Iain D. H. Oswald; Christopher Barry; Duncan J. Francis; William G. Marshall; Colin R. Pulham; Adam S. Cumming

The high-pressure, high-temperature epsilon-form of the widely used explosive RDX has been structurally characterised using a combination of diffraction techniques, and a sample of this form has been successfully recovered to ambient pressure.


High Pressure Research | 2016

PEARL: the high pressure neutron powder diffractometer at ISIS

Craig L. Bull; Nicholas P. Funnell; Matthew G. Tucker; S. Hull; Duncan J. Francis; William G. Marshall

ABSTRACT The PEARL instrument at ISIS has been designed for, and dedicated to, in situ studies of materials at high pressure, using the Paris–Edinburgh press. In recent years, upgrades to the instrument have led to improvements in data quality and the range of achievable pressures and temperatures; currently 0.5–28 GPa and 80–1400 K. This paper describes the technical characteristics of the instrument, its current capabilities, and gives a brief overview of the science that has been performed, using representative examples.


High Pressure Research | 2010

High-pressure structural studies of energetic compounds

Iain D. H. Oswald; David I. A. Millar; Alistair J. Davidson; Duncan J. Francis; William G. Marshall; Colin R. Pulham; Adam S. Cumming; Alistair R. Lennie; John E. Warren

The phase diagram of the energetic material hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been explored using X-ray and neutron diffraction from ambient pressure to 8 GPa. Two phases of RDX have been structurally characterized. The high-pressure γ-polymorph exists above 4 GPa while the metastable β-polymorph has been isolated from the high boiling point solvent nitrobenzene. Interestingly, neutron diffraction measurements at high pressures and high temperatures show that the β-polymorph isolated under ambient conditions is not the same polymorph as can be accessed at high pressures and temperatures.


Journal of Applied Crystallography | 2008

Thermoelastic properties of magnesiowüstite, (Mg1−xFex)O: determination of the Anderson–Grüneisen parameter by time-of-flight neutron powder diffraction at simultaneous high pressures and temperatures

Ig Wood; L Vocadlo; David P. Dobson; G. David Price; Ad Fortes; Frances J. Cooper; J W Neale; Andrew M. Walker; William G. Marshall; Matthew G. Tucker; Duncan J. Francis; H J Stone; C A McCannon

The ability to perform neutron diffraction studies at simultaneous high pressures and high temperatures is a relatively recent development. The suitability of this technique for determining P-V-T equations of state has been investigated by measuring the lattice parameters of Mg1-xFexO ( x = 0.2, 0.3, 0.4), in the range P < 10.3 GPa and 300 < T < 986 K, by time-of-flight neutron powder diffraction. Pressures were determined using metallic Fe as a marker and temperatures were measured by neutron absorption resonance radiography. Within the resolution of the experiment, no evidence was found for any change in the temperature derivative of the isothermal incompressibility, partial derivative K-T/partial derivative T, with composition. By assuming that the equation-of-state parameters either varied linearly or were invariant with composition, the 60 measured state points were fitted simultaneously to a P-V-T-x equation of state, leading to values of partial derivative K-T/partial derivative T = -0.024 (9) GPa K-1 and of the isothermal Anderson-Gruneisen parameter delta(T) = 4.0 (16) at 300 K. Two designs of simultaneous high-P/T cell were employed during this study. It appears that, by virtue of its extended pressure range, a design using toroidal gaskets is more suitable for equation-of-state studies than is the system described by Le Godec, Dove, Francis, Kohn, Marshall, Pawley, Price, Redfern, Rhodes, Ross, Schofield, Schooneveld, Syfosse, Tucker & Welch [Mineral. Mag. (2001), 65, 737-748]. (c) 2008 International Union of Crystallography Printed in Singapore - all rights reserved.


Chemical Communications | 2009

The crystal structure of beta-RDX-an elusive form of an explosive revealed

David I. A. Millar; Iain D. H. Oswald; Duncan J. Francis; William G. Marshall; Colin R. Pulham; Adam S. Cumming


CrystEngComm | 2010

The effect of pressure on the crystal structure of L-alanine

Nicholas P. Funnell; Alice Dawson; Duncan J. Francis; Alistair R. Lennie; William G. Marshall; Stephen A. Moggach; John E. Warren; Simon Parsons


CrystEngComm | 2008

A study of the high-pressure polymorphs of L-serine using ab initio structures and PIXEL calculations

Peter A. Wood; Duncan J. Francis; William G. Marshall; Stephen A. Moggach; Simon Parsons; Elna Pidcock; Andrew L. Rohl


CrystEngComm | 2008

High-pressure polymorphism in L-serine monohydrate: identification of driving forces in high pressure phase transitions and possible implications for pressure-induced protein denaturation

Russell D. L. Johnstone; Duncan J. Francis; Alistair R. Lennie; William G. Marshall; Stephen A. Moggach; Simon Parsons; Elna Pidcock; John E. Warren


Journal of Alloys and Compounds | 2005

Pressure dependence of the crystal structure of SrCeO3 perovskite

Kevin S. Knight; William G. Marshall; Nikolaos Bonanos; Duncan J. Francis

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William G. Marshall

Rutherford Appleton Laboratory

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Adam S. Cumming

Defence Science and Technology Laboratory

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Ad Fortes

Rutherford Appleton Laboratory

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