Wednesday 10 July 2013, Strathblane & Cromdale Halls, 16:30-18:30
Poster session B - Geosciences and extreme conditions I: Molecular systems
P.085 The high-pressure behaviour of the H2O-CO2 system
D Amos1, C Bull1, A Falenty2, W Kuhs2 and J Loveday1
1
University of Edinburgh, UK, 2Universität Göttingen, Germany
Gas hydrates are a type of icy compound that are typically formed under the application of pressure and
incorporate simple gas molecules into their crystal structures. In some cases these materials are clathrate in type,
where cages of H-bonded water molecules form a host structure to guest gas molecules trapped inside. These
compounds are of broad interest as they are found to occur widely in nature and have potential application in
hydrogen storage technologies as well as carbon sequestration. Furthermore where clathrates form these are also
valuable systems for studying fundamental water-water and water-guest interactions.
The existence of a CO2 clathrate hydrate formed at modest pressures ( 100 bar) is well known, and its
transformation at a pressure of 0.6 GPa into a new, currently unsolved, hydrate phase was recently discovered
[1]. The high pressure behaviour of this binary system has, however, never been fully studied and the reported
absence of any CO2 hydrate phases above 1 GPa is in stark contrast to other gas hydrate systems, which are
observed to undergo transition to more dense hydrate phases with stability up to 100 GPa in some cases. We will
present the results of a comprehensive study of the H2O-CO2 system including the molten state up to 5 GPa using
both neutron and x-ray diffraction. Our studies confirm the previously observed dissociation above 1 GPa, provide
the first information on the compressibility of the clathrate hydrate phase, and new insight into the structure of the
high pressure phase reported by Hirai and co-workers.
[1]
H. Hirai, K. Komatsu, M. Honda, T. Kawamura, Y. Yamamoto, T. Yagi of J. Chem. Phys. 133, 124511 (2010)
P.086 A neutron diffraction study of the high pressure behaviour of metallic lithium ammonia
C Bull1, J Loveday2, R Nelmes2, D Amos2, C Wilson2, M-E Donnelly2 and T Hansen3
ISIS Facility, Rutherford Appleton Laboratory, UK, 2SUPA, School of Physics and Astronomy and Centre for Science
at Extreme Conditions, University of Edinburgh, UK, 3Institut Laue–Langevin, France
Many alkali and alkaline earth metals dissolve in ammonia and, depending on the concentration of metal species,
these ‘‘expanded-metal’’ solutions can either be insulating or metallic. The Li:NH3 system is one of the most
interesting as it forms the lowest temperature liquid metal known. The ambient pressure phase diagram shows the
onset of the metallic state at 4 mol% of metal, with a eutectic point at 89 K and 20 mol% of metal. Above this
concentration, the freezing point rises rapidly and stoichiometric solid Li(NH3)4 forms. At ambient pressure,
superconductivity has not been observed, but pressure has been proposed as a means to tune the electron density
of states and induce superconductivity. Recent calculations indicated that the ambient pressure cubic
structure remains stable up to 200 GPa. We will present neutron diffraction studies of Li(ND3)4 at high pressure
showing that is not so.
When compressed at 80 K the ambient pressure cubic phase simply decomposes into a mixture of ammonia,
lithium amide and fluid deuterium at 2.5-3.0 GPa. However, when the liquid phase is compressed into a solid at
160 K and 2.0 GPa, or when the cubic phase is first compressed and then warmed to these P and T conditions
from low temperature, a very different behaviour is observed. A new diffraction pattern is observed which appears to
be a new phase of Li(ND3)4 and the first high-pressure phase to be discovered in the system. This provides the basis
for new computational and experimental effort on this interesting material and its possible superconductivity.
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We acknowledge helpful insights from computations carried by Eva Zurek (University of Buffalo) and Chris Pickard
(UCL).
P.087 High-pressure and variable-temperature structural studies of the energetic material, 2,4-dinitroanisole
(DNAN)
P Coster1, C Henderson1, S Hunter1, W Marshall2, A Kleppe3, C Tang3 and C Pulham1
1
The University of Edinburgh, UK, 2ISIS Pulsed Neutron and Muon Facility, UK, 3Diamond Light Source, UK
2,4-dinitroanisole (DNAN) is an energetic material, developed as an insensitive replacement for TNT in melt-cast
explosive formulations. While DNAN-based formulations demonstrate greatly reduced sensitivity to accidental
initiation compared to those using TNT, issues remain with the replacement of TNT with DNAN. For instance, DNAN
based formulations have demonstrated catastrophic levels of irreversible growth during heat-cycling, with volume
increases of up to 15% reported.
In order to investigate the role of polymorphism in the irreversible growth of DNAN, high-pressure and variabletemperature neutron and x-ray diffraction studies have been performed. The phase diagrams of both form-I and -II
of DNAN have been explored for the first time.
In the case of DNAN-II, two high-pressure phase transitions were found, one above 0.16 GPa (DNAN-III) and the
second above 3.4 GPa (DNAN-IV). No further phase transitions were noted up to 5.88 GPa. In addition, variable
temperature studies demonstrated that the DNAN-II to DNAN-III transition also occurs when DNAN-II is cooled below
267K. The thermal expansion of the DNAN-II/III lattice was investigated from 150K to 363K, demonstrating that an
abrupt change in the thermal behaviour of lattice parameters occurs at the DNAN-II/III transition. From these
combined crystallographic studies, the structure of DNAN-III has been solved, showing it is closely related to DNANII. A DNAN-I/III transition was not found during variable temperature studies on DNAN-I, as may be expected given
the dissimilarity between the DNAN-I and DNAN-II structures. The role of polymorphic transitions in the melt-cast
processing of DNAN has also been investigated.
P.088 High pressure neutron diffraction: A gentler way to study energetic materials
C Henderson1, P Coster1, H Maynard-Casely2, W Marshall3 and C R Pulham1
1
University of Edinburgh, UK, 2Australian Synchrotron, Australia, 3ISIS, UK
High-pressure studies of energetic materials are important in determining their properties at conditions approaching
detonation. In this work the results from high-pressure studies of the energetic material CL-20 using both
synchrotron radiation and neutron sources are compared. These results are striking and show that in contrast to the
severe radiation damage induced by the intense x-ray beam, there is no radiation damage observed in the neutron
experiment. Refinement of the unit cell parameters allowed the derivation of an accurate equation of state for CL20. TATB, an energetic material known to be susceptible to radiation damage was also studied using high-pressure
neutron diffraction with no evidence of damage to the material, and again an equation of state was obtained. These
studies highlight the advantages of studying radiation sensitive materials using neutrons.
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P.089 Distinguishable water populations in montmorillonite
M Bestel1, F Juranyi2, T Gimmi3, L R Van Loon4, M A Glaus4, G J Schneider5, M Zamponi5 and L W Diamond6
1
Laboratory for Neutron Scattering, Paul Scherrer Institut, Switzerland and Institute of Geological Sciences,
University of Bern, Switzerland, 2Laboratory for Neutron Scattering, Paul Scherrer Institut, Switzerland, 3Laboratory
for Waste Management, Paul Scherrer Institut, Switzerland and Institute of Geological Sciences, University of Bern,
Switzerland, 4Laboratory for Waste Management, Paul Scherrer Institut, Switzerland, 5Jülich Centre for Neutron
Science, Germany, 6Institute of Geological Sciences, University of Bern, Switzerland
Swelling clays exhibit a complex porous structure, which gains in volume in contact with water. High resolution
neutron backscattering could distinguish between micro- (or interlayer-) and meso- to macropore water in
montmorillonite, using the fact, that water in very small pores can be significantly undercooled. The ratio between
these two water populations could be measured for a series of Na- and Cs- montmorillonite samples.
The gravimetric water content was found to be the determining factor for the ratio between the two water
populations. The effect of water saturation, etc. is negligible compared to the experimental error bars. (As expected,
the curves differ for Na- and Cs- montmorillonite.)
Additionally, neutron diffraction experiments revealed that the amount of the interlayer pore water can be well
estimated from surface measurements for samples with 1 to 2 water layer in the interlayer. However at higher
gravimetric water content the effective density of the interlayer pore water is significantly lower.
Further measurements have shown, that water in the micropores cannot crystallize but solidify in a glassy structure.
Surprisingly, its reduced vibrational density of states differ from that of the amorphous ice, exhibiting an extra peak
at about 3meV, unobserved before.
P.090 A 3 kbar hydrogen-compatible gas loader for Paris-Edinburgh presses
S Klotz1, J Philippe1, C Bull2, J Lovedau3 and R Nelmes3
1
IMPMC - Université P&M Curie, France, 2STFC / University of Edinburgh, UK, 3University of Edinburgh, UK
We present a device which allows compressed gases to be loaded into large-volume opposed anvils used for highpressure neutron scattering in the multi-10 GPa range [1]. The gases are initially loaded into clamps which can then
be inserted into VX-Paris-Edinburgh load frames. The system is compatible with all inert gases as well as hydrogen
and permits loading pressures of up to 3 kbar for which most gases have densities close to that of the liquid at
ambient pressure. The device should have applications for the study of simple molecular solids as well as for
loading gases as pressure transmitting media.
[1]
S. Klotz, J. Philippe, C.L. Bull, J.S. Loveday, R.J. Nelmes, High Pressure Research 33(1) (2013)
P.091 Development of P-T variable system and its application to the neutron diffraction study of ice VI under high
pressure and low temperature
K Komatsu, K Nakayama, T Koizumi and H Kagi
The University of Tokyo, Japan
We recently developed the new pressure(P)-temperature(T) controlling system, which allows us to control P and T
independently so as to contribute the understanding of metastable phases [1]. The main feature of this system is
the thermal insulation between anvils and high-P ram by using glass-fiber-reinforced-plastic (FRP) and cubic
stabilized zirconia so that T can be quickly changeable (up to 20 K/min), the conventional hydraulic oil instead of
helium gas can be used even at low-T, and much less consuming liquid nitrogen. As an application of this system,
in-situ neutron diffraction experiment for ice VI under high-P and low-T were conducted at PLANET, J-PARC. Note that
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the availability of compression under low-T is essentially important to make fine powder of ice VI. 99.9 % D2O and
Pb as a pressure marker were capsuled into the TiZr gasket and loaded up to 10 tons. Temperature was
subsequently dropped down to 200 K, compressed until single phase of ice VI appeared and obtained neutron
diffraction at several P-T conditions. The observed neutron diffraction patterns were well explained by the disordered
model of ice VI at any P-T conditions we explored (0.6-1.7 GPa, 100-200 K). The unit cell volume as a function of
temperature down to 100 K at 1.3 GPa was observed but found no anomaly, in contrast with the results of previous
studies which used D2O with 0.01 mol/L DCl [2], or pure H2O [3]. Both neutron diffraction and V-T relationship show
no strong evidence of the transition involving with the proton ordering under low temperature.
[1]
[2]
Komatsu et al. (2013) High Press. Res., in press.
Salzmann et al. (2009) Phys. Rev. Lett., 103, 105701
[3]
Mishima et al. (1979) J. Chem. Phys., 70, 2037
P.092 exTAS - next-generation TAS for small samples and extreme conditions
J Kulda1, A Piovano1, S Roux1 and A Hiess2
1
Institut Laue-Langevin, France, 2European Spallation Source, Sweden
Implementation of horizontally and vertically focusing optics in the past two decades has enabled efficient studies
of excitations in sub-cm3-sized single crystals on three-axis spectrometers (TAS). After completion of the ThALES
project in 2014 the ILL TAS portfolio will represent the state of the art in this respect. With the exTAS proposal within
the ILL Endurance program we wish to stimulate a further paradigm shift into the domain of mm3-sized samples. The
project goal is to boost the sensitivity limits by combining highly focused mm-sized focal spots in the direct space
with optimized resolution volume and shape in the momentum and energy space. We propose a tabletop size
spectrometer layout enclosed in a shielded hutch, minimizing all interactions with the environment. Its
monochromator will be illuminated by a pre-filtered beam from a cold-neutron supermirror guide through a narrow
input slit (1-10 mm), minimizing the need of heavy shielding on the individual spectrometer components. The short
distances between the spectrometer axes, together with the conventional size of the optical elements will permit to
trade-off the momentum resolution in favor of higher count rate in cases of need. The optional availability of a thin
(1-2 mm) silicon monochromator and analyzer will permit to boost energy resolution (vanadium width) by a factor
of 5-10, without compromising the beam acceptance angles. The light and compact instrument design will facilitate
positioning of its components with sub-millimeter accuracy, needed to match the reduced focal spot size. This
contribution is aimed to present the fundamental exTAS concepts based on ray-tracing results and to stimulate
discussion on diverse project options.
P.093 The polymorphic phase transformations in chlorpropamide at temperature and high pressure
N Loshak1, D Kozlenko1, L Bulavin2 and S Kichanov1
1
Joint Institute for Nuclear Research, Russia, 2Taras Shevchenko National University of Kiev, Ukraine
The processing of typical pharmaceutical formulation involves applications of various type of stresses each of which
can have profound effects on the formulation chemical or physical properties. A good model compound for studies
of polymorphism effects in drugs is chlorpropamide C10H13ClN2O3S. It belongs to a group of sulphonylurea
compounds and it is used as antidiabetic drug. Several polymorphs of chlorpropamide are known.
The crystal structure and vibrational spectra of molecular crystal of chlorpropamide C10H13ClN2O3S have been
studied by means of X-ray diffraction and Raman spectroscopy at pressures up to 4.2 GPa and in the temperature
range 300-450 K. At ambient conditions the structure of chlorpropamide has orthorhombic symmetry with space
group P212121 (γ-form). At high pressure P > 1.2 GPa the polymorphic phase transition into monoclinic γ-phase
with space group P21 have been observed. At ambient pressure there are no phase transitions in chlorpropamide up
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to temperature of melting T = 396 K. At the recrystallization the initial α form of chlorpropamide the appearance of
additional polymorphic ε-phase have been found. After the recrystallization the high pressure application leads to
partial amorphization of chlorpropamide at pressures of about P 3 GPa. Baric and temperature coefficients for
α, γ and ε forms of chlorpropamide have been calculated.
P.094 Structural studies of expanded high density amorphous ice
R Nelmes, J Loveday and C Bull
University of Edinburgh, UK
The discovery that high density amorphous ice (HDA) expands when warmed at pressures below 0.5 GPa was
unexpected and transformed our understanding of this important system [1]. Expanded high density amorphous ice
(eHDA) appears to be the relaxed form of amorphous ice at low pressures and may be a hyperviscous liquid at
temperatures around 140 K. As such its behaviour is very different from unrelaxed HDA (uHDA) which had generally
been used for studies of amorphous ices. For example, eHDA has been shown to transform cleanly and
discontinuously to and from low density amorphous ice (LDA) [1] and this result has ended debate about the nature
of the LDA to HDA transition, and has provided support for the two liquids model of water [2].
We will present high-pressure diffraction studies of eHDA across its entire range of stability (0.1-0.8 GPa) carried
out using the Paris-Edinburgh press. We will present data on the structure close to the transformation to LDA at 0.1
GPa and explore the relationship between eHDA and very high density amorphous ice which forms above 0.8 GPa.
[1]
[2]
R.J.Nelmes et al, Nature Phys., 2, 414-418, (2006)
P.H.Poole et al, Nature, 360, 324-328, (1992)
P.095 The methane content of methane hydrate-II
J Loveday and R Nelmes
University of Edinburgh, UK
The discovery that at pressures of 1 GPa small simple molecules like methane, nitrogen, argon etc. form hydrates
with the hexagonal clathrate structure (SH) was unexpected [1,2]. SH is composed of one type of very large cage of
H-bonded water molecules and two types of smaller cages and had previously been found only with large organic
‘guest’ molecules in the large cages. In small molecule systems the guest fills the large cage multiply – for example,
in SH argon hydrate there are 5 atoms in the large cage with another atom in each of the small cages to give a total
of 10 atoms in the unit cell [3]. The methane occupancy in SH methane hydrate-II (MH-II) has been the subject of
some debate [4]. Raman studies [5] found a change in the C-H vibron at 1.3 GPa which was interpreted as a
partial filling of the large cages. This interpretation implies (improbable) empty large cages below 1.3 GPa. A careful
analysis of neutron diffraction data reveals that there is a change in occupancy at 1.3 GPa. But this change
affects all cages so that below this pressure there are 7 molecules in the unit cell including 3 in the large cages,
while, above 1.3 GPa, MH-II has close to the maximum possible occupancy with 10 molecules in the unit cell
including 5 in the large cage.
[1]
[2]
[3]
[4]
[5]
J.S.Loveday et al, Nature, 410, 661-663, (2001)
J.S.Loveday and R.J.Nelmes, Phys. Chem. Chem. Phys., 10, 937-950, (2008)
Y.Manakov et al, J. Incl. Phen. and Mac. Chem., 48, 11, (2008)
C.A.Tulk et al, J. Chem. Phys., 136, 054502, (2012)
T.Kumazaki et al, Chem. Phys. Lett., 388, 18, (2004)
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P.096 Neutron diffraction under extreme conditions
J Loveday1, C Bull2, C Wilson2, D Amos2, M-E Donnelly2, S Klotz3 and R Nelmes2
1
Edinburgh University, UK, 2Centre for Science at Extreme Conditions and SUPA, University of Edinburgh,
UK, 3Institut de Minéralogie et de Physique des Mileux Condensés, Université P et M Curie, France
The ability to obtain accurate structural data with neutron diffraction at high pressure has provided a wealth of new
information [1,2]. The Paris-Edinburgh press can access pressures up to 30 GPa [3] and temperatures between 10
and 1000 K and its open Bridgman-anvil geometry allows a wide range of difficult samples (low-boiling point gases,
liquids, air and water-sensitive systems, and liquid- and solid-gas mixtures) to be loaded and in some cases turned
into single crystals [4,5]. This flexibility has allowed us to obtain valuable information on topics as diverse as the
fundamental behaviour of hydrogen bonds [1] to the origin of the methane in Titan’s atmosphere [2].
We have recently carried out studies of simple molecular systems and mixtures at high pressure. These include; the
ordering of ice VI under pressure, the first high-pressure investigation of the expanded metal Li(NH3)4, the
structures and transitions of amorphous ices, and new hydrogen and other gas storage materials based on water
and other cage forming molecules. Results from a range of these systems will be presented.
[1]
[2]
[3]
[4]
[5]
R.J.Nelmes et al, Phys. Rev. Lett., 71 , 1192-1195,(1993)
R.J.Nelmes et al, Nature Phys. , 2, 414-418, (2006)
S.Klotz et al, Appl. Phys. Lett., 14, 1735-1737, (1995)
C.L.Bull et al, J. Appl. Cryst., 44, 831-838, (2011)
S.Klotz et al High Press. Res. In press
P.097 Development of high-pressure sample environments for TOF single crystal neutron diffractometer SENJU at JPARC
K Munakata1, A Nakao1, R Kiyanagi2, K Kaneko2, T Osakabe2, T Ohhara1, T Hanashima1, K Oikawa2, T Kawasaki2, I
Tamura2 and Y Uwatoko3
1
Comprehensive Research Organization for Science and Society (CROSS), Japan, 2Japan Atomic Energy Agency,
Japan, 3The University of Tokyo, UK
High-pressure technique is a powerful tool for physical property measurements and structural analyses as well as
other external field conditions, such as magnetic field and temperature. In the field of neutron experiments,
measurements under high-pressure conditions are also useful and attractive. SENJU is a single crystal time-of-flight
neutron Laue diffractometer, designed for precise crystal and magnetic structure analyses under multiple extreme
conditions, constructed at BL18 in MLF/J-PARC.
We are planning to introduce high-pressure sample environments into SENJU. At a first step, we have prepared
small clamp type piston-cylinder cell made of copper-beryllium alloy, which can be expected to reach maximum
pressure of about 2 GPa. As feasibility test, we tried to perform the measurements by using this pressure cell in
SENJU, at atmospheric pressure and at room temperature. A single crystal of NaCl, 1.4x1.3x1.7 mm3 in size, was
enclosed in the pressure cell together with liquid pressure-transmitting medium. We found more than fifty Bragg
reflections of NaCl through the pressure cell after appropriate exposure time. This result shows that this pressure cell
is available enough as one of the high-pressure environment devices of SENJU. We will present more details about
current high-pressure sample environments of SENJU.
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P.098 X-ray and neutron diffraction studies of the NaCl hydrate under pressure
K Nakayama, K Komatsu and H Kagi
University of Tokyo, Japan
Recent studies reveal that LiCl and NaCl can dissolve into high pressure ice VII [1, 2]. These findings might change
the simple picture that salt-water system could have been considered as mixture of pure ices and salt/salt hydrate.
The phase relationship of salt-water systems and the properties of salt hydrates under pressure are surprisingly
unexplored in spite of its importance in the planetary sciences.
We investigated the phase relationship of the NaCl-H2O system in the range of 0-6 GPa and 200-300 K and
discovered a new NaCl hydrate from powder X-ray diffraction experiments using diamond anvil cells. The crystal
structure of the newly found NaCl hydrate except for the hydrogen atoms was derived by the direct methods from
single crystal X-ray diffraction experiments. The structure of NaCl hydrate is monoclinic, space group C 2/m, with a
= 11.358(13) Å, b = 11.842(11) Å, c = 10.869(10) Å, β = 119.52(4)º at 1.9 GPa and 298 K.
To determine the hydrogen positions, we conducted powder neutron diffraction experiments of the NaCl hydrate at
BL-11 “PLANET” in J-PARC. NaCl saturated D2O water was used as a starting material and diffraction patterns were
obtained at 2.2 GPa and 200-296 K. The patterns were roughly consistent with the simulated pattern derived from
the structure model of the X-ray experiments. However, it was not possible to determine hydrogen positions mainly
due to the phase mixtures of ice, NaCl, and NaCl hydrate, which indicates that the sample was in a non-equilibrium
state depending on the heterogeneous distribution of salt in the sample chamber.
[1]
[2]
M. R. Frank et al. (2006) Phys. Earth Planet. In. 155, 152
S. Klotz et al. (2009) Nature Mater. 8, 405
P.099 The DN-6 neutron diffractometer for studies of microsamples under extreme conditions
B Savenko1, D Kozlenko1, S Kichanov1, E Lukin1, A Belushkin1 and A Bulkin2
1
Joint Institute for Nuclear Research, Russia, 2Petersburg Nuclear Physics Institute, Russia
The novel high pressure neutron diffraction instrument - DN-6 diffractometer for studies of microsamples under
extreme conditions is presented. This diffractomer are mounted at high flux pulse reactor IBR-2. The system of head
and tail parts of neutron guide, the frame of mechanical unit of the DN-6 diffractometer, the neutron beam
collimator, ring shape gas detector and its electronic systems and software for control and data collection from this
detector are described. The first experiments results obtined at DN-6 diffractometer were presented.
P.100 Recent advances in high pressure neutron diffraction at the SNS
C Tulk1, M Guthrie2, R Boehler2, A Moreira dos Santos1 and J Molaison1
1
SNS, USA, 2CIW/GL, USA
Abstract unavailable
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P.101 Sample environment cell for neutron reflectometry under extreme conditions
P Wang, M Taylor, A Lerner, D Hickmott and J Majewski
Los Alamos National Laboratory, USA
One key gap to study the interfacial behaviors of materials under extreme conditions is the lack of well designed
sample environment cell capable of handling P-T conditions close to or above supercritical conditions. To build up
the capability of studying high P-T surface/interface, Lujan Center developed a special designed pressure cell which
allows us to reach 200 MPa and 200 °C (in the future such cell will be equipped with with in-situ spectroscopic
Raman and IR capabilities). Neutron is highly penetrating, which is able to “see through” high P-T aluminum cell
walls and examining the surface/interface properties. Besides the pressure cell itself, the high P-T cell system
includes three other subsystems: temperature, pressure and sample chamber environment control systems.
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