High-pressure Crystallization Research Articles

Combined crystal structure prediction and high-pressure crystallization in rational pharmaceutical polymorph screening.

Organic molecules, such as pharmaceuticals, agro-chemicals and pigments, frequently form several crystal polymorphs with different physicochemical properties. Finding polymorphs has long been a purely experimental game of trial-and-error. Here we utilize in silico polymorph screening in combination with rationally planned crystallization experiments to study the polymorphism of the pharmaceutical compound Dalcetrapib, with 10 torsional degrees of freedom one of the most flexible molecules ever studied computationally. The experimental crystal polymorphs are found at the bottom of the calculated lattice energy landscape, and two predicted structures are identified as candidates for a missing, thermodynamically more stable polymorph. Pressure-dependent stability calculations suggested high pressure as a means to bring these polymorphs into existence. Subsequently, one of them could indeed be crystallized in the 0.02 to 0.50 GPa pressure range and was found to be metastable at ambient pressure, effectively derisking the appearance of a more stable polymorph during late-stage development of Dalcetrapib.

Structural Behavior of Long-Chain Imidazolium-Based Ionic Liquid [C10mim]Cl–Water Mixtures

The structural behavior of long-chain imidazolium-based ionic liquid [C10mim]Cl–water mixtures has been investigated in detail by low-temperature and high-pressure crystallization methods, and the solid forms have been fully characterized by single-crystal X-ray diffraction. Form I, a monohydrate, crystallizes from solutions containing 6–8% (w/w) water; its structure exhibits bilayers, in which the cations alternate from layer to layer to create hydrophobic and hydrophilic regions. Form II, which is a Z′ > 1 structure, incorporates a variable amount of water content (from pseudo-hemihydrate to pseudo-monohydrate) depending on the sample treatment and environment; this form crystallizes from solutions containing < ca. 6% (w/w) water and exhibits a double bilayered structure characterized by ordered and disordered regions. Forms I and II have been obtained at both low-temperature and high-pressure conditions. Form III is a trihydrate that has been exclusively obtained under high-pressure conditions above 0....

Carbon isotope fractionation during high pressure and high temperature crystallization of Fe–C melt

There is a growing body of experimental evidence that iron carbides can play an important role in the mantle both as a host of carbon and as a redox couple (Fe–C) determining the nature of reduced phases. If carbides are significant in the mantle, it could be of interest to know if any carbon isotope fractionation accompanies carbide crystallization. A series of high-pressure and high-temperature experiments were performed on carbide crystallization from a Fe–C melt. An offset of 2‰ was observed between the δ13C values of Fe3C and Fe–C melt at 6.3GPa and 1400°C. The carbon isotopic compositions of Fe3C and diamond crystallizing from a single carbon source near the peritectic region at 6.3GPa differ by 2.5‰. Fe7C3 was detected as a quench phase during Fe–C melt quenching. Our results have important implications for understanding carbon isotope distributions in iron meteorites and indicate that iron carbide crystallization may be a significant mechanism for carbon isotope heterogeneity in the Earth's mantle.

High Pressure Crystallization of Vitamin E‐containing Radiation Cross‐linked UHMWPE

One of our aims in developing ultrahigh molecular weight polyethylene (UHMWPE) joint implants is to improve the fatigue strength of cross‐linked UHMWPEs without sacrificing their wear resistance induced by cross‐linking. High pressure crystallization (HPC) of uncross‐linked UHMWPE, which results in the formation of less hindered extended chain crystals, increased fatigue strength. Vitamin E, also an antioxidant, acted synergistically with HPC and the resulting UHMWPE had increased wear and fatigue strength. In this study, we hypothesized that vitamin E‐blended, cross‐linked, and high pressure crystallized UHMWPE (X‐VEHPE) would have higher wear resistance and fatigue strength compared to radiation cross‐linked UHMWPE. To test this hypothesis, we irradiated 0.1 wt% vitamin E‐blended UHMWPE, subsequently radiation cross‐linked it to various doses and terminally high pressure crystallized it. We used bi‐directional pin‐on‐disc wear testing, tensile mechanical testing, and fatigue crack propagation resistance testing. We found that X‐VEHPE required less radiation dose and less cross‐linking to achieve the same wear rate when compared to irradiated UHMWPE and had improved fatigue resistance at the same wear rate. Therefore, this UHMWPE presented about 46 and 87% improvement in fatigue strength compared to irradiated and irradiated/melted UHMWPE and may be a feasible alternative for joint implants.

Water in Hawaiian garnet pyroxenites: Implications for water heterogeneity in the mantle

Mapping the compositional variability of the Earth's mantle is fundamental for understanding mantle dynamics, crustal recycling and melt generation. The geochemistry of intraplate oceanic basalts in particular points to a heterogeneous convecting mantle, often explained by variable proportions of fertile (pyroxenite, eclogite) and depleted (peridotitic) domains. A key parameter necessary to constrain the Earth's deep processes is water because it influences melting and affects the physical properties of the Earth's mantle. However, there are only a few direct water determinations on samples of the oceanic mantle. Here we report water concentrations by FTIR on garnet pyroxenite xenoliths from Salt Lake Crater vent, Oahu, Hawaii, in order to constrain the role of lithological variability in the distribution of water in the upper oceanic mantle. The clinopyroxenes have 260 to 576ppm H2O and the orthopyroxenes about half these amounts. Curiously, garnets have water concentrations below detection limits (<0.5ppm H2O). Calculated melts in equilibrium with the pyroxenes have, on average, 2.3±0.4wt.% H2O and 243±83 H2O/Ce. These H2O concentrations are similar to estimates for the H2O concentration of primary magmas of the rejuvenated Hawaiian stage volcanism, and 3 to 5 times higher than primary magmas of the shield stage. This supports earlier conclusions where the pyroxenites are interpreted as high pressure cumulates from alkali magmas similar to the rejuvenated stage magmas within the Pacific lithosphere. The reconstructed bulk pyroxenites have 211 to 467ppm H2O, similar to estimates for the source of Hawaiian magmas and two to four times higher than estimates for the depleted MORB source (~100ppm H2O). Despite their high water concentrations, however, the bulk pyroxenites have much lower H2O/Ce ratios than the MORB source (35–115 vs. 150–210, respectively) or Hawaiian magma sources (>160). The discrepancy between the low H2O/Ce ratios in the bulk pyroxenites and high H2O/Ce in the equilibrium melts is consistent with experimental data that predicts 4 to 5 times higher partition coefficient for Ce than H in these pyroxenes. Therefore, the process of high-pressure crystallization in the oceanic lithosphere will create pyroxene-rich lithologies which are paradoxically, both “wet” (i.e., high H2O concentrations) and “dry” (low H2O/Ce ratios) compared to the source of their parental melts. Phlogopite is present as a trace phase in these rocks (<0.4% modal) with relatively minor contribution on the bulk water contents. The coupled high H2O, low H2O/Ce ratios of the pyroxenites are similar to the inferred source of several Enriched Mantle (EM)-type Ocean Island Basalts (OIB), like the Samoa, Pitcairn, Society, and Kergulen hot spots, as well as the EM-1 type Koolau endmember of the Hawaiian magmas. We suggest that recycling of pyroxenite-bearing oceanic lithosphere can explain the relatively high H2O and low H2O/Ce ratios of some EM-type OIB. Our data suggests a link between lithological variability and heterogeneous water distribution in the upper mantle.

High-pressure behavior and crystal–fluid interaction under extreme conditions in paulingite [PAU-topology

The compressional behavior and the P-induced crystal–fluid interaction of a natural paulingite-K have been explored on the basis of in-situ single-crystal and powder X-ray diffraction, and in-situ single-crystal Raman spectroscopy with a diamond anvil cell and a series of diverse pressure-transmitting fluids (i.e., silicone-oil, methanol:ethanol=4:1, methanol:ethanol:water=16:3:1). No evidence of any phase transition was observed within the P-range investigated, independent on the used P-fluids. The compressional behavior of paulingite is significantly different in response to the different nature of the P-fluids. A drastically lower compressibility is observed when the zeolite is compressed in methanol:ethanol or, even more noticeably, in methanol:ethanol:water mix. We ascribe this phenomenon to the different crystal–fluid interaction at high pressure: (1) silicone-oil is a “non-penetrating” P-medium, because of its polymeric nature, whereas (2) methanol–ethanol and water are “penetrating” P-fluids. The P-induced penetration processes appear to be completely reversible on the basis of the X-ray diffraction data alone. The Raman spectra collected after the high-pressure experiments show, unambiguously, that a residual fraction of methanol (and/or ethanol and probably even extra H2O) still resides in the zeolitic sub-nanocavities; such molecules are spontaneously released after a few days at atmospheric pressure. The actual compressibility of paulingite-K is that obtained by the compression experiment in silicone-oil, with an isothermal bulk modulus K0=β0−1=18.0(1.1)GPa. Paulingite appears to be one of the softest zeolite ever found.

Oscillatory Sr isotopic signature in plagioclase megacrysts from the Damiao anorthosite complex, North China: Implication for petrogenesis of massif-type anorthosite

Formation of Proterozoic massif-type anorthosites is known to be related to polybaric process involving early high-pressure crystallization of plagioclase and high-Al orthopyroxene megacrysts at mantle–crust boundary, followed by emplacement of plagioclase-dominated mushes to shallow-level crust. Therefore, the plagioclase megacrysts record important information about the magmatic sources and crystallization process of anorthosites. The ~1.74-Ga Damiao complex, North China, comprises >90vol.% anorthosites and leuconorites containing abundant plagioclase megacrysts associated with minor high-Al orthopyroxene megacrysts (HAOMs). The plagioclase megacrysts are generally euhedral to subhedral (mostly 1 to 30cm in diameter), and some of them contain very fine lamellae of orthoclase and undefined Fe–Ti-rich minerals (1–5μm). The HAOMs occur as subhedral grains or as angular grains with an intercumulus relationship to the plagioclase megacrysts. They contain abundant thin, regular lamellae of exsolved plagioclase (15–20vol.%), indicative of originally high-Al features (originally 6.0–7.3wt.% Al2O3). Based on the Al-in-orthopyroxene geobarometry, the HAOMs and associated plagioclase megacrysts are constrained to be crystallized together at pressures of 9.4–11.2kbar (33–36km), indicative of their crystallization at lower crust depths or crust–mantle boundary. In contrast, orthopyroxene grains from late differentiation phases such as oxide-apatite gabbronorites do not contain plagioclase lamellae, and have much lower Al2O3 contents (1.5 to 1.7wt.%), indicating final crystallization at <5kbar (<15km). Four plagioclase megacrysts analyzed in this study have slightly different compositions, but collectively they all display comparable, oscillatory variations of An values (43–55), Sr (1100–1800ppm), Ba (800–1400ppm), La (2 to <7ppm) and 87Sr/86Sr ratios (0.70283–0.70466) from center to rim. Although Sr content is also likely related to pressures, our work suggests that the oscillatory chemical and Sr isotopic signature of the plagioclase megacrysts was mainly controlled by the compositions of the magmas, which temporally changed in the deep magma chamber. A mixing-assimilation modeling, based on Sr contents and initial 87Sr/86Sr ratios of synchronous mantle-derived mafic dykes and ancient lower crustal xenoliths in North China, suggests that the parental magma was initially a depleted mantle-derived basaltic magma that assimilated with ~30% lower crustal materials (Al2O3=15–24wt.%; Sr=800–2000ppm) or partial melts of the lower crust when ponding at the base of lower crust. We consider that an increasing of Al2O3 in the basaltic magma due to assimilation may have triggered saturation of plagioclase, because the oscillatory chemical and isotopic patterns are consistent from center to rim in all plagioclase megacrysts, indicative of initiation of the assimilation processes at the very beginning of plagioclase crystallization. Our study supports the model that the parental magmas were derived from partial melting of the depleted mantle combined with all-important crustal contamination in deep magma chambers or during rising of crystal mushes, and this may also account for variable isotopic signature for different phases in many anorthosite suites.

Prolonged Life and Fast Secondary Formation of the Electrodes of Lead-Acid Battery during Charge-Discharge Cycle under High-Pressure Crystallization

To make larger capacity of charge–discharge of lead-acid batteries at high pressure after the initial formation of Plante-type electrodes, we studied the effect of high pressure on prolonged life testing. Electrode life was evaluated by determining the time of detachment of active crystals (Pb, PbOx and PbSO4) or the drop in ampere-hour efficiency during the charge–discharge cycle. Prolonged life testing, active crystals (Pb, PbOx and PbSO4) on the electrodes used in charge–discharge cycles at atmospheric pressure were easily detached when the electric current was increased to 2.7 mA/cm2, but the electrodes used at 100 MPa remained very tough until 8.0 mA/cm2 was reached. To increase the electric capacity of electrodes (i.e. in the second formation process), long-term charge–discharge was performed at a high electric current (5.3 mA/cm2). Faster second formation of electrodes at this high current was impossible at a charge of 3.6 As under atmospheric pressure, but it was possible at 6 As and 100 MPa.

High‐Pressure Processes

High-pressure technologies have a long history. As early as 1914, Percy W. Bridgeman was awarded the Nobel Prize for discovering that microorganisms can be deactivated when subjected to high pressure of 6000 bar. Only a few years later, Haber and Bosch were both awarded Nobel Prizes for their work on the ammonia process. Since then, many new applications have been developed ranging from the mere use of pressure for fluid transport or component production to diverse processes for product extraction, precipitation and production, and even extending to food technologies. Previously, high-pressure processes have always taken place hidden behind thick-walled containers, whereas nowadays the focus is increasingly on making the processes visible within the containers and to analyze them with optical measuring methods. The laser-optical analysis of the particle formation during the SAS-process or the Raman-spectroscopic analysis of the chemical reaction processes inside the crystallization containers, as well as the corresponding corrosive attack at 300 MPa and about 700 °C or the production of new materials by high-pressure crystallization, are only a few examples. Furthermore, liquid food is sterilized in large volumes in supercritical gases, new substances, increasingly with pharmaceutical relevance, are extracted with more and more selective methods, and pharmaceutically-usable formulations and morphologies are studied in supercritical precipitation processes. But even the mere use of pressurized energy has opened new doors. Accordingly, the hydrotransport of ore slurries over distances of many 100 km is a feasible method to circumvent road construction in difficult terrain or the commonly used rail technology – nowadays with more than 200 MPa – and helps to optimize the combustion process. Furthermore, the technology of water jet cutting is using increasingly higher pressures of up to 800 MPa, and by adding abrasives, cuts in the range of up to 100 mm depth are possible. The control of wear and tear in both of these processes presents a challenge to scientific research. Last but not least, high-pressure technology can play an important role in cancer research. As pressure-treated cancer cells can be traced by the human immune system, a treatment for cancer requiring the human body to aid itself is on the horizon. Research has shown that pulsating high pressure has a distinctly higher apoptotic effect on cells and at the same time a much better impact on cell inactivation, so that continuous high-pressure inactivating processes have become possible. Furthermore, a step away from batch processes and towards continuous processes remains an important goal. These examples show that high-pressure technology is still a fascinating field of research bearing many exciting issues and gaining fresh momentum when related to energy efficiency as a relevant topic. High pressure plays a key role regardless of whether hydrogen or an alternative method is being considered for energy storage. The European Working Group for High Pressure Process Technology as an international network dedicates itself to all these topics and has initiated and realized the Fifth International Symposium of High Pressure Process Technology in Belgrade. The working group consists of partners from academia and industry from about 20 countries. Besides the symposia, this group also organizes an annual intensive Lifelong Learning-summer-course over a fortnight, focusing on High Pressure Process Technology for around 60 students (30 ECTS – European Credit Transfer and Accumulation System). This special issue of Chemical Engineering & Technology comprises a selection of the papers presented and discussed during the Belgrade Symposium. Moreover, a wide range of additional topics was also presented and discussed regarding their scientific or industrial relevance. Professor Dr.-Ing. Eberhard Schlücker, Institute for Process Machinery and Systems Engineering and Chairman of the European Working Group for High Pressure Process Technology.

High pressure crystallization and crystallography of glucose isomerase

Crystallization of protein is still a "bottleneck" for the three-dimensional (3D) structure analysis of a protein molecule. Therefore, the study on the acceleration of the crystallization is important. Visuri et al. repoted, for the first time, that the crystallization of glucose isomerase (GI) crystals was significantly enhanced with increasing pressure [1], while they did not discuss further effects of pressure on the crystallization. We measured solubilities, growth rates of a crystal face, step velocities and two-dimensional (2D) nucleation rates, three-dimensional (3D) nucleation rates of the GI crystal under high pressure. From these results, we found the negative molar volume change of crystallization delta V, the decrease in a step ledge surface energy and the increase in a step kinetic coefficient with increasing pressure. Activation volume of crystallization delta V‡ was discussed and the absolute value of it was almost half of that of delta V [2]. X-ray crystallography is also very important to study how the three dimensional structure of protein is related to its function under high pressure at atomic level. Kundrot et al. analyzed the crystal structure of lysozyme at 100 MPa using a beryllium (Be) cell. The crystal was prepared under 0.1 MPa. Charron et al. reported that thaumatin crystals grown under 150 MPa were analyzed under 0.1 MPa. Although Kundrot et al. concluded that the protein structure under high pressure was compressed, they could not estimate the influence of the bond structure of the crystal at 0.1 MPa on the compressed structure. In Charron's case, the thaumatin structures in crystals prepared under 0.1 MPa and 150 MPa were almost identical, when they did X-ray analyses of both crystals at 0.1 MPa. From these two results, we considered that compression of the crystals was reversible. We conducted both Kundrot's and Charron's methods for GI using a stand-alone type Be vessel [3]. We found that (1) GI molecule was reversibly compressed under high pressure, (2) the distributions of water sites around GI molecules were almost identical in the range of pressures from 0.1 to 100 MPa.

Periodicity and its breaking in compressed ferroelectric dabco monosalts

1,4-Diazabicyclo[2.2.2]octane (dabco) monosalts form a fascinating group of compounds, which exhibit exceptional dielectric properties. They can be described by a general formula: dabcoHX, where X= Br-, I-, ClO4-, BF4-and ReO4-. DabcoHI is the first material for which anisotropic relaxor properties were reported.[1] The ferroelectric relaxors are particularly desired for numerous practical applications in electronics, including miniature electronic devices and new methods of storing electricity in capacitors. Moreover, organic relaxors are environment friendly and easier to produce and to dispose off, than inorganic ceramic relaxors of mixed perovskites and doped with lead. DabcoHI undergoes a large number of transformations at elevated pressure and temperature, however analogous dabcoHBr exists only in three forms. Exceptionally rich phase diagram of ten phases was also revealed for dabcoHClO4. At normal conditions in dabco monosalts the dabcoH+cations are NH+···N bonded into linear chains, but pressure can considerably modify that pattern, and the weak hydrogen bonds are relevant for the formation of new polymorphs at high pressure.[2,3] In all dabcoHI polymorphs the NH+···N bonded chains of dabcoH+cations are retained, however the chains are linear at 0.1 MPa and high pressure induces modulation of the chain with gradually increased periodicity. In dabcoHBr only phase III is NH+···N bonded. Although phase II of dabcoHClO4isostructural with phase II of dabcoHBF4, it behaves differently on lowering temperature than it was observed in dabcoHBF4. The polymorphic structures of dabco salts differ mainly in the arrangement of the chains and iodide anions, in the dabco conformation, and in the location of protons. When crystallized from methanol, above 1.70 GPa, dabcoHI forms solvates, and the high-pressure crystallization from aqueous solution leads to hydration already at 0.50 GPa.

The impact of pressure on β-Cyclodextrin·acetaminophen inclusion complexes

Cyclodextrins (CDs) have attracted considerable interest as model systems in supramolecular host-guest chemistry. They are described as hollow truncated cones with a hydrophilic outer surface and a nonpolar inner cavity suitable for small molecules' encapsulation.[1] By virtue of their character, CDs are used as excipients to improve the aqueous solubility of active pharmaceutical ingredients (APIs). High-pressure crystallisation techniques have been established as a suitable tool for exploring the phenomenon of polymorphism and solvate formation of pharmaceutical compounds throughout numerous examples reported in the literature.[2] Thus, exploring the inclusion-complex formation and the polymorphic behaviour of CDs with APIs at high pressure would be an interesting extension of the technique. The present work describes the attempt of an in-situ crystallisation of β-CD·acetaminophen inclusion complex and compression studies of the known β-CD·acetaminophen complex[3] in different crystallisation media at pressures up to 1.0 GPa. A new high-pressure crystal form observed at 0.8 GPa as well as unexpected results are presented herein. The crystals have been characterised by means of polarised optical microscopy, Raman spectroscopy and single-crystal X-ray diffraction using both home and synchrotron sources.

Experimental study into the petrogenesis of crystal-rich basaltic to andesitic magmas at Arenal volcano

Arenal volcano is nearly unique among arc volcanoes with its 42 year long (1968–2010) continuous, small-scale activity erupting compositionally monotonous basaltic andesites that also dominate the entire, ~7000 year long, eruptive history. Only mineral zoning records reveal that basaltic andesites are the result of complex, open-system processes deriving minerals from a variety of crystallization environments and including the episodic injections of basalt. The condition of the mafic input as well as the generation of crystal-rich basaltic andesites of the recent, 1968–2010, and earlier eruptions were addressed by an experimental study at 200 MPa, 900–1,050 °C, oxidizing and fluid-saturated conditions with various fluid compositions [H2O/(H2O + CO2) = 0.3–1]. Phase equilibria were determined using a phenocryst-poor (~3 vol%) Arenal-like basalt (50.5−wt% SiO2) from a nearby scoria cone containing olivine (Fo92), plagioclase (An86), clinopyroxene (Mg# = 82) and magnetite (Xulvö = 0.13). Experimental melts generally reproduce observed compositional trends among Arenal samples. Small differences between experimental melts and natural rocks can be explained by open-system processes. At low pressure (200 MPa), the mineral assemblage as well as the mineral compositions of the natural basalt were reproduced at 1,000 °C and high water activity. The residual melt at these conditions is basaltic andesitic (55 wt% SiO2) with 5 wt% H2O. The evolution to more evolved magmas observed at Arenal occurred under fluid-saturated conditions but variable fluid compositions. At 1,000 °C and 200 MPa, a decrease of water content by approximately 1 wt% induces significant changes of the mineral assemblage from olivine + clinopyroxene + plagioclase (5 wt% H2O in the melt) to clinopyroxene + plagioclase + orthopyroxene (4 wt% H2O in the melt). Both assemblages are observed in crystal-rich basalt (15 vol%) and basaltic andesites. Experimental data indicate that the lack of orthopyroxene and the presence of amphibole, also observed in basaltic andesitic tephra units, is due to crystallization at nearly water-saturated conditions and temperatures lower than 950 °C. The enigmatic two compositional groups previously known as low- and high-Al2O3 samples at Arenal volcano may be explained by low- and high-pressure crystallization, respectively. Using high-Al as signal of deeper crystallization, first magmas of the 1968–2010 eruption evolved deep in the crust and ascent was relatively fast leaving little time for significant compositional overprint by shallower level crystallization.

A high-pressure polymorph of propionamide from in situ high-pressure crystallisation from solution

Abstract The structure of a high-pressure polymorph of propionamide is reported from synchrotron single-crystal X-ray diffraction data. The polymorph was obtained by in situ high-pressure crystallisation from solution in a diamond-anvil cell at 0.9 GPa; its structure is 23% denser than that of the ambient-pressure polymorph at STP. PIXEL lattice and dimer energies calculations indicate that the ambient- and high-pressure polymorphs are energetically competitive. Together with acetamide and formamide, this is the third high-pressure polymorph of an aliphatic amide crystallising as a Z′=2 structure; the H-bonded network is however significantly different from the ones reported for the other two compounds. This study highlights the power of in situ high-pressure crystallisation techniques for accessing novel polymorphic forms of molecular compounds.

Performance of a beam-multiplexing diamond crystal monochromator at the Linac Coherent Light Source.

A double-crystal diamond monochromator was recently implemented at the Linac Coherent Light Source. It enables splitting pulses generated by the free electron laser in the hard x-ray regime and thus allows the simultaneous operations of two instruments. Both monochromator crystals are High-Pressure High-Temperature grown type-IIa diamond crystal plates with the (111) orientation. The first crystal has a thickness of ~100 μm to allow high reflectivity within the Bragg bandwidth and good transmission for the other wavelengths for downstream use. The second crystal is about 300 μm thick and makes the exit beam of the monochromator parallel to the incoming beam with an offset of 600 mm. Here we present details on the monochromator design and its performance.

A single-component molecular superconductor.

The pressure dependence of the resistivities of a single-component molecular conductor, [Ni(hfdt)2] (hfdt = bis(trifluoromethyl)tetrathiafulvalenedithiolate) with semiconducting properties at ambient pressure was examined. The four-probe resistivity measurements were performed up to ∼10 GPa using a diamond anvil cell. The low-temperature insulating phase was suppressed above 7.5 GPa and the resistivity dropped, indicating the superconducting transition occurred around 7.5-8.7 GPa with a maximum Tc (onset temperature) of 5.5 K. The high-pressure crystal and electronic band structures were derived by the first-principle calculations at 6-11 GPa. The crystal was found to retain the semiconducting band structure up to 6 GPa. But the electron and hole Fermi surfaces appear at 8 GPa. These results of the calculations agree well with the observation that the pressure-induced superconducting phase of [Ni(hfdt)2] appeared just above the critical pressure where the low-temperature insulating phase was suppressed.

Lead isotope signatures of Kerguelen plume-derived olivine-hosted melt inclusions: Constraints on the ocean island basalt petrogenesis

The nature of magmatic sources reflected by isotopic composition of the ocean island basalt (OIB) remains an on-going question in igneous geochemistry. To constrain the magmatic sources for OIB related to the Kerguelen plume activity, we performed detailed microanalytical investigation of the 21.4 Ma picritic basalt (MD109-D6-87) dredged during the “Marion Dufresne” cruise on a seamount between Kerguelen Archipelago and Heard Island. Lead isotope compositions of olivine-hosted melt inclusions and matrix glasses were measured by Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) and Secondary Ion Mass Spectrometry (SIMS). We also performed major and trace element microanalyses and mapping of the inclusions and the host olivine phenocrysts by electron microprobe (wavelength-dispersive X-ray spectroscopy, WDS). The observed significant major element (K 2 O/P 2 O 5 , Al 2 O 3 /TiO 2 ) and Pb isotope ( 207 Pb/ 206 Pb and 208 Pb/ 206 Pb) heterogeneities of parental melts (MgO = 7–10 wt.%) during early high pressure crystallisation stage (200–300 MPa, Fo 82–86 mol%), and relative homogeneity at later lower-pressure crystallisation stage (< 100 MPa, Fo 75–80 mol%) are interpreted by mixing between “Plume” and “Assimilant” melts during magma residence and transport. Lead isotope composition of the parental basaltic melts was inherited from both heterogeneous mantle and the Kerguelen Plateau crust. High K 2 O/P 2 O 5 (> 4), Al 2 O 3 /TiO 2 (> 4) ratios are attributed to assimilation of the plateau basaltic crust (≥ 50 wt.%) by the melts in the magma chamber at palaeodepths from 6 to 9 km. The crustal assimilation may have happened through plagioclase dissolution. The large chemical and isotopic heterogeneity of the parental OIB melts found by in situ microanalyses in this study suggests that the bulk rock chemistry alone cannot provide enough information to constrain the nature of the magmatic sources. • The new data on the Kerguelen melts are important for understanding the OIB genesis. • The plume mantle composition cannot be known from the OIB bulk rock chemistry. • Heterogeneous sources affect composition of the OIB parental melts. • Crustal assimilation happens through plagioclase dissolution. • Magma mixing is a dominant and fast process in the evolution of the OIB.

Low temperature and high pressure crystals of room temperature ionic liquid: N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate

Crystals of room temperature ionic liquid (RTIL) are obtained separately at low temperature or under high pressure. The RTIL is N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate, [DEME][BF4]. At ambient pressure, low-temperature (LT) crystals appeared on slow cooling. By simultaneous X-ray diffraction and differential scanning calorimetry (DSC) measurements, metastable monoclinic and stable orthorhombic phases coexist in pure [DEME][BF4]. Furthermore, the DSC thermal trace indicates that the metastable monoclinic phase was stabilized by adding water. In contrast, on compression process up to 7.6 GPa, crystallization is completely suppressed even upon slow compression. Direct observations using optical microscopy also support no crystal domain growth on compression process. High-pressure (HP) crystals at room temperature were seen only on decompression process, where two different kinds of crystals appeared subsequently. By crystal structure analysis, the LT crystal structures have no relation with the HP ones. Moreover, both metastable monoclinic phase at low temperature and higher pressure crystal has a folding molecular conformation and anti-parallel pairing of the [DEME] cation as the instability factors.

Fast charging of lead–acid batteries enabled by high-pressure crystallization

Lead-acid batteries were electrically charged and discharged more quickly under high pressures than under atmospheric pressure due to high-pressure crystallization induced by the former condition. High-pressure crystallization can generate extremely small crystals with large supersaturation and small mass transfer rates. Crystals of PbSO4 on the electrodes were observed by scanning electron microscopy, and the crystals became smaller when the operative pressure increased, even when faster charging was carried out. Additionally, the amount of electrical current transferred to the electrodes was larger for electrodes charged and discharged at high pressure. This high-pressure charge-discharge process is expected to improve the quality of lead-acid batteries.

CRISTAPRESS: An optical cell for structure development in high-pressure crystallization

An original optical high-pressure cell, named CRISTAPRESS, has been especially designed to investigate phase transitions of complex liquids, i.e., polymers, polymer blends, nano-composites, etc. The design of the cell is based on the optical properties of morphological entities through in situ light depolarizing microscopic observations. Pressure up to 200 MPa with a fine temperature control up to 300 °C can be applied. A striking advantage of this cell is the possibility to select the pressure transmitting medium that can be water, silicone oil, a fluid in the supercritical state, etc. The potential of the novel technique was demonstrated by carrying out time-resolved measurements during polymer crystallization induced by water pressure. These preliminary experimental investigations permit to discriminate the role of the barometric and thermal histories on the kinetics of polymer growth, as well as on the subsequent morphologies. It should lead to new reliable crystallization kinetics models.