Multi-anvil Cell Research Articles

Large volume multianvil cell assembly for hydrothermal synthesis and conversions up to 6.5 GPa and 400°C

ABSTRACT A multianvil cell assembly with octahedral edge length 25 mm has been adapted for high pressure investigations involving water-rich environments up to 6.5 GPa and 400°C. Water-rich samples are confined in Teflon containers with a volume up to 300 mm3. Applicability tests were performed between 250 and 400°C by investigating the transformation of amorphous titania particles close to the rutile–TiO2-II (∼5 GPa) phase boundary, and the transformation of amorphous silica particles close to the quartz–coesite (∼2.5 GPa) and coesite–stishovite (∼7 GPa) phase boundaries. The performed experiments employed 25.4 mm tungsten carbide anvils with a truncation edge length of 15 mm. The sample pressure at loads approaching 820 t was estimated to be around 6.5 GPa. The large volume multianvil cell is expected to have broad and varied application areas, ranging from the simulation of geofluids to hydrothermal synthesis and conversion/crystal growth in aqueous environments at gigapascal pressures.

Ab initio study of Li-Mg-B superconductors

LiB, a predicted layered compound analogous to the ${\mathrm{MgB}}_{2}$ superconductor, has been recently synthesized via cold compression and quenched to ambient pressure, yet its superconducting properties have not been measured. According to prior isotropic superconductivity calculations, the critical temperature (${T}_{\mathrm{c}}$) was expected to be only 10--15 K. Using the anisotropic Migdal-Eliashberg formalism, we show that the ${T}_{\mathrm{c}}$ may actually exceed 32 K. Our analysis of the contribution from different electronic states helps explain the detrimental effect of pressure and doping on the compound's superconducting properties. In the search for related superconductors, we screened Li-Mg-B binary and ternary layered materials and found metastable phases with ${T}_{\mathrm{c}}$ close to or even 10--20% above the record 39 K value in ${\mathrm{MgB}}_{2}$. Our reexamination of the Li-B binary phase stability reveals a possible route to synthesize the LiB superconductor at lower pressures readily achievable in multianvil cells.

Superhard transparent polycrystalline cubic boron nitride

Polycrystalline cubic boron nitride (PcBN) has been synthesized at 14 GPa and high temperatures of 1300–2000 °C in a two-stage multi-anvil cell. Sintered PcBN synthesized at 1700–1800 °C and 14 GPa with a grain size of ∼200 nm is optically transparent with a transmittance of ∼70% at wavelengths of 400–1500 nm and has the Vickers hardness of ∼63–69 GPa. Analyses with scanning and transmission electron microscopy reveal that PcBN can be strengthened by introducing nanometer-scale grains and microscopic defects at high pressure and temperature. The optical transparency of the bulk PcBN synthesized at high pressure and temperature can be explained by the very thin intergranular films between grains. The present sintered PcBN is the second-hardest transparent material after diamond and can be used for windows in extreme conditions.

Maximum multianvil cell assembly running on WC anvils with certain size

Since the invention of split sphere multianvil apparatus, the maximum sample size that can be obtained on tungsten carbide (WC) anvils with a certain size has always been a neglected issue. The maximum volume of loaded gaskets and the maximum multianvil cell assembly operating on given size WC anvils are calculated by a simplified geometric model. As a concrete example, the maximum volume of loaded gaskets in different assemblies (18/11, 25/17 (octahedral edge-length/anvil truncation edge-length, in millimetre)) and different initial shapes of octahedrons (octahedron chamfered or not) running on WC anvils with 25.4 mm edge-length are calculated. The maximum initial sizes of gaskets in different assemblies are also calculated according to the maximum volume of loaded gaskets. Using the pyrophyllite octahedron as the pressure transmission medium, the pressure calibration of 14/8, 18/11, and 25/17 assembly are carried out on WC cubes, of which the edge-length is 25.4 mm, to verify the calculated results. The cell pressure is calibrated by in situ observing resistance change caused by phase transition of pressure calibration material at high pressure. All assemblies run stably and no blow-out phenomenon occurs. The experimental results show that the pressure transfer efficiency of 18/11 and 25/17 assembly with chamfered octahedron are better than previous reported results in the same pressure range. The experimental results also indicate that the calculations of the gasket in this work are valid. And the 25/17 assembly with chamfered octahedron can run stably on WC cube with 25.4 mm edge-length. In addition, using graphite tubes as heater, heating structure designs of different assemblies (14/8, 18/11, 25/17) are completed, in which the 14/8 assembly can achieve the highest temperature of 2300 ℃. The diameter of sample chamber is almost one centimeter in 25/17 assembly. This work contributes to the development of assembly techniques for secondary anvil made of polycrystalline diamond materials to obtain larger sample volumes under higher pressure conditions.

Incompatibility of argon during magma ocean crystallization

We report results from multi-anvil (MA) and laser-heated diamond anvil cell (LH-DAC) experiments that synthesize high-pressure phases, including bridgmanite, ferropericlase, stishovite, and ultramafic liquid, in the presence of an argon-rich fluid. The goal of the experiments is to constrain the equilibrium distribution of argon in magma ocean environments. Argon concentrations in LH-DAC experiments were quantified by electron microprobe analysis, while argon concentrations in MA experiments were quantified by laser-ablation mass spectrometry and electron microprobe analysis. Our LH-DAC experiments demonstrate that argon solubility in ultramafic liquid is near or above 1.5 wt.% at conditions between 13–101 GPa and 2300–6300 K. Argon concentrations in bridgmanite and ferropericlase synthesized in LH-DAC experiments range from below detection to 0.58 wt.%. Argon concentrations in bridgmanite and ferropericlase synthesized in MA experiments range from below detection to 2.16 wt.% for electron microprobe measurements and laser-ablation measurements. We interpret this wide range of argon concentrations in minerals to reflect the variable presence of argon-rich fluid inclusions in analytical volumes. Our analyses therefore provide upper limit constraints for argon solubility in high-pressure minerals (<0.015 wt.%) across all mantle pressures and temperatures. The combination of relatively high argon solubility in ultramafic liquid (∼1.5 wt.%) and low argon solubility in minerals implies argon incompatibility (Dbridgmanite−meltAr < 0.01, Dferropericlase−meltAr < 0.01) during magma ocean crystallization and that the initial distribution of argon, and likely other neutral species, may be controlled by liquids trapped in a crystallizing magma ocean. We thus predict a basal magma ocean would be enriched in noble gases relative to other regions of the mantle. Moreover, we predict that the noble gas parent-daughter ratio of magma ocean cumulates pile will increase with crystallization, assuming refractory and incompatible behavior for parent elements.

High-Pressure Phase Diagrams of Na2CO3 and K2CO3

The phase diagrams of Na 2 CO 3 and K 2 CO 3 have been determined with multianvil (MA) and diamond anvil cell (DAC) techniques. In MA experiments with heating, γ -Na 2 CO 3 is stable up to 12 GPa and above this pressure transforms to P 6 3 /mcm-phase. At 26 GPa, Na 2 CO 3 - P 6 3 /mcm transforms to the new phase with a diffraction pattern similar to that of the theoretically predicted Na 2 CO 3 - P 2 1 /m. On cold compression in DAC experiments, γ -Na 2 CO 3 is stable up to the maximum pressure reached of 25 GPa. K 2 CO 3 shows a more complex sequence of phase transitions. Unlike γ -Na 2 CO 3 , γ -K 2 CO 3 has a narrow stability field. At 3 GPa, K 2 CO 3 presents in the form of the new phase, called K 2 CO 3 -III, which transforms into another new phase, K 2 CO 3 -IV, above 9 GPa. In the pressure range of 9–15 GPa, another new phase or the mixture of phases III and IV is observed. The diffraction pattern of K 2 CO 3 -IV has similarities with that of the theoretically predicted K 2 CO 3 - P 2 1 /m and most of the diffraction peaks can be indexed with this structure. Water has a dramatic effect on the phase transitions of K 2 CO 3 . Reconstruction of the diffraction pattern of γ -K 2 CO 3 is observed at pressures of 0.5–3.1 GPa if the DAC is loaded on the air.

Shock compression of niobium from first-principles

The equation of state (EOS) of bulk niobium (Nb) was investigated within the framework of density functional theory, with Mermin’s generalization to finite temperatures. The shock Hugoniot for fully-dense and porous Nb was obtained from canonical ab initio molecular dynamics simulations with Erpenbeck’s approach based on the Rankine-Hugoniot jump conditions. The phase space was sampled along isotherms between 300 and 4000 K, for densities ranging from ρ=5.5 to 12 g/cm3. Results from simulations compare favorably with room-temperature multianvil and diamond anvil cell data for fully-dense Nb samples and with a recent tabulated SESAME EOS. The results of this study indicate that, for the application of weak and intermediate shocks, the tabular EOS models are expected to give reliable predictions.

ChemInform Abstract: Poling‐Written Ferroelectricity in Bulk Multiferroic Double‐Perovskite BiFe0.5Mn0.5O3.

AbstractPolycrystalline BiFe0.5Mn0.5O3 is prepared by hot pressing of stoichiometric amounts of Bi2O3, Fe2O3, and Mn2O3 (Au capsule in multianvil cell, 6 GPa, 1100 °C, 1.5 h).

Ab initio engineering of materials with stacked hexagonal tin frameworks.

The group-IV tin has been hypothesized to possess intriguing electronic properties in an atom-thick hexagonal form. An attractive pathway of producing sizable 2D crystallites of tin is based on deintercalation of bulk compounds with suitable tin frameworks. Here, we have identified a new synthesizable metal distannide, NaSn2, with a 3D stacking of flat hexagonal layers and examined a known compound, BaSn2, with buckled hexagonal layers. Our ab initio results illustrate that despite being an exception to the 8-electron rule, NaSn2 should form under pressures easily achievable in multi-anvil cells and remain (meta)stable under ambient conditions. Based on calculated Z2 invariants, the predicted NaSn2 may display topologically non-trivial behavior and the known BaSn2 could be a strong topological insulator.

ChemInform Abstract: High‐Pressure Investigations of Lanthanoid Oxoarsenates. Part 1. Single Crystals of Scheelite‐Type Ln[AsO4] Phases with Ln: La—Nd from Monazite‐Type Precursors.

AbstractTransparent single crystals of Ln[AsO4] (Ln: La—Nd) are obtained by the pressure‐induced monazite‐to‐scheelite type phase transition (Walker‐type multi‐anvil cell, 11 GPa, 1100—1300 °C, 15 min).

ChemInform Abstract: Creating Reactivity with Unstable Endmembers Using Pressure and Temperature: Synthesis of Bulk Cubic Mg0.4Fe0.6N.

AbstractA novel rock salt Mg0.4Fe0.6N solid solution is obtained by hot pressing a 70:30 at.% mixture of Fe and Mg together with NaN3 (MgO capsule in multianvil cell, 15 GPa, 1800 K, 1 min).

Synthesis of thin-film black phosphorus on a flexible substrate

We report a scalable approach to synthesize a large-area (up to 4 mm) thin black phosphorus (BP) film on a flexible substrate. We first deposit a red phosphorus thin-film on a flexible polyester substrate, followed by its conversion to BP in a high-pressure multi-anvil cell at room temperature. Raman spectroscopy and transmission electron microscopy measurements confirm the formation of a nano-crystalline BP thin-film with a thickness of around 40 nm. Optical characterization indicates a bandgap of around 0.28 eV in the converted BP, similar to the bandgap measured in exfoliated thin-films. Thin-film BP transistors exhibit a field-effect mobility of around 0.5 cm2 V−1 s−1, which can probably be further enhanced by the optimization of the conversion process at elevated temperatures. Our work opens the avenue for the future demonstration of large-scale, high quality thin-film BP.

ChemInform Abstract: A High‐Pressure Polymorph of Phosphorus Oxonitride with the Coesite Structure.

AbstractThe title high‐pressure PON polymorph is obtained from cristobalite‐type PON by high‐temp, high‐pressure treatment (multianvil cell, 1300 °C, 15.5 GPa, 1 h).

ChemInform Abstract: Pentacoordinate Phosphorus in a High‐Pressure Polymorph of Phosphorus Nitride Imide P4N6(NH).

AbstractThe title γ‐P4N6(NH) polymorph is obtained by high‐temperature high‐pressure synthesis using P3N5 and NH4Cl in the molar ratio of 4:1 (multianvil cell, 14 GPa, 1200 °C, 3 h).

ChemInform Abstract: Orthorhombic In2O3: A Metastable Polymorph of Indium Sesquioxide.

AbstractOrthorhombic o′‐In2O3 (Rh2O3(II)‐type, space group Pbcn, Z = 4) is synthesized in macroscopic quantities (ca. 10—100 mm3) from rhombohedral corundum‐type rh‐In2O3 at 8—9 GPa and 600—1100 °C in multianvil and toroid cell assemblies.

Pressure-temperature phase diagram of Ti2O3and physical properties in the golden Th2S3-type phase

In this paper, the pressure and temperature conditions of the synthesis of a recently discovered golden Th${}_{2}$S${}_{3}$-type phase of titanium sesquioxide (Ti${}_{2}$O${}_{3}$) are studied, along with its physical properties. In combined x-ray diffraction and Raman high-pressure studies at room-temperature we found signatures of an isostructural transition at pressures near \ensuremath{\sim}8--10 GPa. This finding was addressed to the well-known isostructural semiconductor-semimetal transition that occurs at ambient pressure near 400--450 K. Above \ensuremath{\sim}10 GPa the golden phase was synthesized under appropriate heating. Based on both in-situ high-pressure high-temperature (HP-HT) studies in diamond anvil cells and ex-situ studies on samples synthesized at HP-HT conditions in multianvil cells, we constructed a pressure-temperature phase diagram of Ti${}_{2}$O${}_{3}$ for the first time. The samples of the golden polymorph were examined by Raman, absorption, and reflectance spectroscopy as well as by measurements of electrical resistivity, Hall effect, thermoelectric power (Seebeck effect), and magnetoresistance. In addition, electronic band-structure calculations were performed. We established that at ambient conditions the golden polymorph of Ti${}_{2}$O${}_{3}$ behaves as a semiconductor with an energy gap of \ensuremath{\sim}0.1--0.2 eV and determined its typical electronic band structure parameters.

High pressure generation using scaled-up Kawai-cell

A scaled-up version of a 6–8 Kawai-type multianvil apparatus equipped with 47-mm WC anvils has been developed at the Institute for the Study of the Earth’s Interior for operation over pressure ranging up to 19 and 24 GPa using the conventional system with larger compressional volumes between 1.2 and 0.4 cm 3, respectively. This system is used under uniaxial compression along cube diagonal of the Kawai-cell up to the press load of 19 MN. Experiments are performed using octahedral pressure media (PM) made of MgO- and ZrO 2-based semi-sintered ceramics and unfired pyrophyllite gaskets. In this study we used “Toshiba-F” grade WC anvils allowing pressure generation up to 24 GPa. We perform pressure calibrations at room and high temperatures, with octahedron/anvil truncation edge-length ratios ( a 0/ b, mm) of 12.2/6, 14/6, 14/7, 16/7, 18/7, 18/9, and 18/10. Different configurations show that an increase in edge-length ratio of a 0 / b permits the achievement of higher pressure, which agrees with the results of Frost at al. (Frost, D.J., Poe, B.T., Tronnes, R.G., Liebske, C., Duba, A., Rubie, D.C., 2004. A new large-volume multianvil system. Phys. Earth Planet. Inter. 143, 507). However, it also shifts the pressure maximum to higher press loads, in some cases exceeding the capacity of a press. Our and Frost et al. (2004) data reveal that the 14/6, 18/8, and 18/10 assemblies are the most suitable in generating pressures of up to 19–24 GPa at 19 MN press load limits. The assemblies with a low a 0/ b ratio have a lower upper pressure limit; however, they exhibit a systematically higher efficiency in pressure generation at low press loads. Consequently, assemblages with high and low a 0/ b ratios should be used in high and low pressure experiments, respectively. For example, the 18/12 assembly is suitable for 5–11 GPa pressure range (Stoyanov, E., Haussermann, U., Leinenweber, K., 2010. Large-volume multianvil cells designed for chemical synthesis at high pressures. High Pressure Res., 30, 175), whereas the 14/6, 18/8 ( Frost et al., 2004), and 18/10 assemblies are suitable for 22–24, 19–23, and 11–19 GPa pressure ranges, respectively. The maximum pressure generation achieved in the present study is 24 GPa, using the 14/6 assembly. This appears to be the maximum pressure level attainable by using WC anvils.

Complex impedance spectroscopy and ionic transport properties of natural leucite, K0.90Na0.08[Al0.98Si2.02]O6, as a function of temperature and pressure

AbstractThe temperature (T) and pressure (P) dependence of dielectric and conductivity properties of natural leucite were determined using complex impedance spectroscopy at frequencies from 103 to 106 Hz. Experiments were carried out in a Walker multi-anvil cell at 1 atm and P from 2.5 to 6 GPa and at T from 350 to 800°C. At pressure &gt;6 GPa and temperature &gt;790°C the leucite broke down to kalsilite+sanidine and dielectric properties for this phase assemblage are given at 6.0–7.0 GPa and T to 1050°C.Leucite conductivity increases with increasing T and decreases with increasing P reflecting their different effects on migration of K cations within the channels in the leucite aluminosilicate framework. Activation energies for K+ migration in leucite increase with increasing pressure (0.74–0.97 eV; 70.0–93.2 kJ/mol) and activation volumes for leucite increase with increasing T (6.42–9.51 cm3/mol; 400–700°C). The latter data provide model K+ cation diameters increasing from 2.7 Å at 400°C to 3.2 Å at 700°C. These values are consistent with the earlier suggestion of Palmer and Salje that the ionic mobility mechanism consists of diffusion along &lt;110&gt; rather than along the main channels parallel to &lt;111&gt;.

Large-volume multianvil cells designed for chemical synthesis at high pressures

Two multianvil cell assemblies with octahedral edge lengths (OEL) of 18 and 25 mm have been developed, which allow sample volumes of up to 153 and 387 mm3, respectively. Pressure calibrations were performed at room temperature and 1200 °C using quenched samples, and at variable temperature using in situ synchrotron measurements. These calibrations employed 25.4 mm tungsten carbide anvils with a truncation edge length of 12 mm for the 18 mm OEL cell (18/12 configuration) and 15 mm for the 25 mm OEL cell (25/15 configuration) and yielded sample pressures of up to 10 and 7.5 GPa, respectively, at loads approaching 800 t. The measured thermal gradients at 1200 °C vary between 5–10 °C/mm (18/12) and 15–20 °C/mm (25/15). By combining large sample/reaction volumes with minimal thermal gradients, the new multianvil cell assemblies are especially useful for chemical synthesis at high-pressure, high-temperature conditions.

Portable multi-anvil device forin situangle-dispersive synchrotron diffraction measurements at high pressure and temperature

A recently developed portable multi-anvil device for in situ angle-dispersive synchrotron diffraction studies at pressures up to 25 GPa and temperatures up to 2000 K is described. The system consists of a 450 ton V7 Paris-Edinburgh press combined with a Stony Brook ;T-cup' multi-anvil stage. Technical developments of the various modifications that were made to the initial device in order to adapt the latter to angular-dispersive X-ray diffraction experiments are fully described, followed by a presentation of some results obtained for various systems, which demonstrate the power of this technique and its potential for crystallographic studies. Such a compact large-volume set-up has a total mass of only 100 kg and can be readily used on most synchrotron radiation facilities. In particular, several advantages of this new set-up compared with conventional multi-anvil cells are discussed. Possibilities of extension of the (P,T) accessible domain and adaptation of this device to other in situ measurements are given.