Duncan J. Francis
Rutherford Appleton Laboratory
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Featured researches published by Duncan J. Francis.
Journal of Applied Crystallography | 2002
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
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
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
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
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
David I. A. Millar; Iain D. H. Oswald; Duncan J. Francis; William G. Marshall; Colin R. Pulham; Adam S. Cumming
CrystEngComm | 2010
Nicholas P. Funnell; Alice Dawson; Duncan J. Francis; Alistair R. Lennie; William G. Marshall; Stephen A. Moggach; John E. Warren; Simon Parsons
CrystEngComm | 2008
Peter A. Wood; Duncan J. Francis; William G. Marshall; Stephen A. Moggach; Simon Parsons; Elna Pidcock; Andrew L. Rohl
CrystEngComm | 2008
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
Kevin S. Knight; William G. Marshall; Nikolaos Bonanos; Duncan J. Francis