Kawai-type Multi-anvil Apparatus Research Articles

Kawai-type multianvil ultrahigh-pressure technology.

Since the large-volume press with a double-stage multianvil system was created by the late Professor Naoto Kawai, this apparatus (Kawai-type multianvil apparatus or KMA) has been developed for higher-pressure generation, in situ X-ray and neutron observations, deformation experiments, measurements of physical properties, synthesis of high-pressure phases, etc., utilizing its large sample volume and capacity in stable and homogeneous high temperature generation compared to those of competitive diamond anvil cells. These advancements in KMA technology have been made primarily by Japanese scientists and engineers, which yielded a wealth of new experimental data on phase transitions, melting relations, and physical characteristics of minerals and rocks, leading to significant constraints on the structures, chemical compositions, and dynamics of the deep Earth. KMA technology has also been used for synthesis of novel functional materials such as nano-polycrystalline diamond and transparent nano-ceramics, opening a new research field of ultrahigh-pressure materials science.

Fe-Mn interdiffusion in aluminosilicate garnets

Precise determination of cation diffusivity in garnet can provide critical information for quantitatively understanding the timescales and thermodynamics of various geological processes, but very few studies have been performed for Fe-Mn interdiffusion. In this study, Fe-Mn interdiffusion rates in natural single crystals of Mn-bearing garnet with 750 ppm H2O are determined at 6 GPa and 1273–1573 K in a Kawai-type multi-anvil apparatus. Diffusion profiles were acquired by electron microprobe and fitted using Boltzmann–Matano equation. The experimental results show that the Fe-Mn interdiffusion coefficient (DFe-Mn) slightly decreases with increasing XFe. The experimentally determined DFe-Mn in Mn-bearing garnet can be fitted by the Arrhenius equation: DFe-Mnm2/s=D0XFenexp-E∗/RT, where E*=1-XFeEMn*+XFeEFe*, D0 = 8.06-6.04+9.87 × 10−9 m2/s, EMn*= 248 ± 27 kJ/mol, EFe*= 226 ± 59 kJ/mol, n = −1.36 ± 0.51. The comparing the present results with previous experimental data suggest that water can greatly enhance the DFe-Mn in garnet. Our results indicate that the time required for homogenization of the compositional zoning of a garnet is much shorter than previously thought.

Reassessment of a bond correction method for in situ ultrasonic interferometry on elastic wave velocity measurement under high pressure and high temperature

ABSTRACT A new bond correction method for simultaneous elastic wave velocity measurement of in situ synchrotron X-ray technique and ultrasonic interferometry combined with a Kawai type multi-anvil apparatus is developed to measure elastic wave velocity precisely. The new method was validated using data from the literature and new elastic constant data of gold obtained under high pressure and high-temperature conditions. Elastic wave velocities corrected using the new method show lower values than those obtained without bond correction and using the conventional method, which show good agreement with datasets by in situ Brillouin scattering measurement and ab initio calculation. When the sample length is 1 mm under ambient conditions, the corrected V P and V S became 3.7% and 1.6% lower, respectively, than values obtained without bond correction under 12 GPa and 900 K. Results show that correcting the bond effect is extremely important, especially when the sample length is less than 1 mm.

Melting phase equilibrium relations in the MgSiO3-SiO2 system under high pressures

Abstract Melting relations in the MgSiO3-SiO2 system have been investigated at 13.5 GPa using a Kawai-type multi-anvil apparatus. The system displays eutectic melting with the eutectic point located at SiO2/(SiO2+MgO) = 0.61 (in mol; which is denoted by XSi hereafter) and at 2350 ± 50 °C. Taking into account the eutectic compositions at lower pressures reported in previous studies, i.e., 0.556 at 1 GPa (Hudon et al. 2005) and 0.60 at 5 GPa (Dalton and Presnall 1997), the eutectic composition is slightly enriched in SiO2 with increasing pressure. The silica-rich eutectic composition is not consistent with the present peridotitic mantle composition (XSi = 0.43). Considering Si incorporation into iron alloys in a magma ocean, however, mass-balance calculations based on an E-chondrite model demonstrate that the silicate magma ocean could have XSi consistent with the present peridotitic mantle.

Fe–Mg interdiffusion in wadsleyite and implications for water content of the transition zone

Fe–Mg interdiffusion rates in polycrystalline wadsleyite aggregates have been determined as a function of water content (up to ∼0.345 wt.% H2O) at 16 GPa and 1373–1773 K in a Kawai-type multi-anvil apparatus. Pre-synthesized water-poor and -rich polycrystalline wadsleyite were used as starting materials. Diffusion profiles were obtained across the interface between Fe-free and -bearing diffusion couples, namely, Mg2SiO4 and (Mg0.9Fe0.1)2SiO4 aggregates by electron microprobe. Fe–Mg interdiffusivities by experiments yield DFe−Mg(m2/s)=D0XFenCH2Orexp⁡[−(E+αXFe+βCH2O)/RT], where D0 = 1.33−0.23+0.20× 10−11 m2/s, n = 0.19 ± 0.04, r = 0.29 ± 0.12, E = 92 ± 2 kJ/mol, α = −45 ± 12, and β = −134 ± 2. Our results indicate that water significantly enhances the rates of Fe–Mg interdiffusion in wadsleyite (a factor of 2.4 for fixed temperature and Fe concentration) compared to that in ringwoodite. Although under hydrous condition the transition zone shows the maximum Fe–Mg mixing efficiency as revealed by diffusivity-depth profile in the mantle, homogenization of existing chemical heterogeneity is still very limited at geological time scale only through solid-state diffusion. Combined with the Nernst–Einstein relation, the results suggest that the contribution of water to the electrical conductivity of wadsleyite or ringwoodite may be overestimated from Fe–Mg interdiffusion data at high water content. Further calculation demonstrates that ∼0.1–0.5 wt.% H2O is sufficient to account for the high conductivity values in the upper part (410–520 km) of the mantle transition zone as observed by electromagnetic induction studies.

Effect of sulfur on sound velocity of liquid iron under Martian core conditions

Sulfur has been considered to be a predominant light element in the Martian core, and thus the sound velocity of Fe-S alloys at relevant high pressure and temperature is of great importance to interpret its seismological data. Here we measured the compressional sound velocity (VP) of liquid Fe, Fe80S20 and Fe57S43 using ultrasonic pulse-echo overlap method combined with a Kawai-type multi-anvil apparatus up to 20 GPa, likely corresponding to the condition at the uppermost core of Mars. The results demonstrate that the VP of liquid iron is least sensitive to its sulfur concentration in the Mars’ whole core pressure range. The comparison of seismic wave speeds of Fe-S liquids with future observations will therefore tell whether the Martian core is molten and contains impurity elements other than sulfur.

Titanium-rich phases in the Earth's transition zone and lower mantle: Evidence from experiments in the system MgO–SiO2–TiO2(±Al2O3) at 10–24 GPa and 1600 °C

Phase relations in the MgSiO3–MgTiO3 and Mg3Al2Si3O12–MgTiO3 systems were studied at 10–24 GPa and 1600 °C using a high-pressure Kawai-type multianvil apparatus. We investigated the full range of starting compositions for the enstatite-geikielite system to derive a P–X phase diagram and synthesize titanium-bearing phases, such as olivine/wadsleyite, rutile, pyroxene, MgTiSi2O7 weberite, bridgmanite and MST-bridgmanite in a wide pressure range. Olivine and pyroxene in run products are characterized by a low titanium content (<0.6 and <0.3 wt% TiO2, respectively) whereas the content of TiO2 in wadsleyite reaches 2 wt% at 12 GPa. The concentration of Ti in MgTiSi2O7 weberite decreases with pressure from 52 wt% TiO2 at 14 GPa to 43 wt% TiO2 at 18 GPa. Two perovskite-type structures (MgSiO3 bridgmanite and Mg(Si,Ti)O3 bridgmanite) were detected in the studied system. MgSiO3 bridgmanite (Brd) is formed at a pressure of >20 GPa and characterized by significant titanium solubility (up to 13 wt% TiO2 at 24 GPa). Mg(Si,Ti)O3 perovskite is formed at a pressure of >17 GPa. The concentration of TiO2 in this phase varies from 29 wt% to 49 wt%. It was found that addition of Ti to the system moves the boundaries of Ol/Wad phase transformations to lower pressures. Addition of Al to the starting material allows us to simulate the composition of natural Ti-rich garnets and bridgmanites. It is important to note that garnet in the Prp-Gkl system is stable throughout a wide pressure range (10–24 GPa). Al incorporation does not affect the distribution of titanium between two types of bridgmanite. It is shown that high contents of Ti stabilize bridgmanite-like compounds at considerably lower pressure than that at the lower mantle/transition zone boundary. Our experiments simulate the composition of natural Ti-rich primary garnet found in eclogite from the Sulu ultrahigh-pressure (UHP) terrane.

Pressure dependence of Si diffusion in γ-Fe

Abstract The pressure dependence of Si diffusion in γ-Fe was investigated at pressures of 5–15 GPa and temperatures of 1473–1673 K using the Kawai-type multi-anvil apparatus to estimate the rate of mass transportation for the chemical homogenization of the Earth's inner core and those of small terrestrial planets and large satellites. The obtained diffusion coefficients D were fitted to the equation D = D0 exp[−(E* + PV*)/(RT)], where D0 is a constant, E* is the activation energy, P is the pressure, V* is the activation volume, R is the gas constant, and T is the absolute temperature. The least-squares analysis yielded D0 = 10-1.17±0.54 m2/s, E* = 336 ± 16 kJ/mol, and V* = 4.3 ± 0.2 cm3/mol. Moreover, the pressure and temperature dependences of diffusion coefficients of Si in γ-Fe can also be expressed well using homologous temperature scaling, which is expressed as D = D0exp{–g[Tm(P)]/T}, where g is a constant, Tm(P) is the melting temperature at pressure P, and D0 and g are 10-1.0±0.3 m2/s and 22.0 ± 0.7, respectively. The present study indicates that even for 1 billion years, the maximum diffusion length of Si under conditions in planetary and satellite cores is less than ∼1.2 km. Additionally, the estimated strain of plastic deformation in the Earth's inner core, caused by the Harper–Dorn creep, reaches more than 103 at a stress level of 103–104 Pa, although the inner core might be slightly deformed by other mechanisms. The chemical heterogeneity of the inner core can be reduced only via plastic deformation by the Harper–Dorn creep.

High-Pressure Sound Velocity Measurements of Liquids Using In Situ Ultrasonic Techniques in a Multianvil Apparatus

Sound velocity and equation of state of liquids provide important constraints on the generation, presence, and transport of silicate and metallic melts in the Earth’s interior. Unlike their solid counterparts, these properties of liquids pose great technical challenges to high-pressure measurements and are poorly constrained. Here we present the technical developments that have been made at the GSECARS beamline 13-ID-D of the Advanced Photon Source for the past several years for determination of sound velocity of liquids using the ultrasonic techniques in a 1000-ton Kawai-type multianvil apparatus. Temperature of the sound velocity measurements has been extended to ~2400 K at 4 GPa and ~2000 K at 8 GPa to enable studies of liquids with very high melting temperatures, such as the silicate liquids.

Pressure generation in the Kawai-type multianvil apparatus and rheology of the Earth's interior

Pressure generation in the Kawai-type multianvil apparatus and rheology of the Earth's interior

Pressure effect on the electromotive force of the type R thermocouple

ABSTRACTThe pressure effect on the electromotive force (EMF) of a Pt13Rh–Pt (type R) thermocouple was examined to determine the temperature measurement accuracy of solid pressure medium apparatuses in high-pressure experiments. Single-wire EMFs were measured up to pressure of 13 GPa and temperature of 1173 K with a Kawai-type multi-anvil apparatus for Pt13Rh and Pt based on the single-wire method. The pressure conditions along the wires were evaluated by in situ X-ray diffraction using synchrotron X-ray radiation. The pressure effect of the Seebeck coefficients of Pt13Rh and Pt were determined by the analysis of the single-wire EMFs and pressure–temperature profiles along the wires and was virtually consistent with those determined in previous studies at lower pressures and temperatures. For type R thermocouple, the difference between the nominal and real temperatures was determined to be as large as –75 K at 13 GPa and 873 K.

High pressure generation in the Kawai-type multianvil apparatus equipped with sintered diamond anvils

ABSTRACTGeneration of high pressure is a key to the investigation of the interior of the Earth. The Kawai-type multianvil apparatus (KMA) has been widely used in the fields of Earth science and material science. In conventional KMA, tungsten carbide (WC) has been used as the second stage anvil material. However, attainable pressure is limited to ∼70 GPa even if newly developed WC is used. Recently, on the other hand, second stage anvils of sintered diamond that is much harder than WC have enabled us to extend the pressure range of KMA up to 120 GPa, corresponding to the pressure of the D” layer in the Earth’s mantle. It is evident that our development of pressure generation facilitates the investigation of the structure and dynamics of the deep mantle of the Earth.

Phase relations of MgSiO3-FeSiO3 system up to 64 GPa and 2300 K using multianvil apparatus with sintered diamond anvils

We have developed techniques to perform precise determinations of phase transition boundaries under the pressure and temperatures corresponding to those of the deep lower mantle, using Kawai-type multianvil apparatus (KMA) with sintered diamond anvils. By optimizing the materials and dimensions of the high-pressure furnace assembly, we achieved stable generation of high temperature to 2300 K, at pressures up to ~64 GPa, which is the highest temperature reported in KMA under such high pressure conditions. Phase relations in the MgSiO3-FeSiO3 system have been studied at pressures from 27 to 64 GPa and temperatures of 1800–2300 K by in situ X-ray diffraction measurements, combined with quench experiments, using synthetic pyroxene samples with chemical compositions of FeSiO3 and (Mg0.4Fe0.6)SiO3 as the starting materials. Our results show that the iron content in MgSiO3 bridgmanite increases almost linearly up to 42 mol% of the FeSiO3 component with increasing pressure in this pressure and temperature range. For higher iron proportions, an assemblage of bridgmanite + magnesiowüstite + stishovite is formed, while the oxide mixture of magnesiowüstite and stishovite is stable for the compositions close to FeSiO3. Our results suggest that bridgimanite with the pure FeSiO3 composition should only be formed at pressures significantly higher than 64 GPa, contradictory to some recent studies using laser-heated diamond anvil cell. It is also suggested that magnesiowüstite inclusions with various iron contents found in some natural diamonds may reflect the formation of magnesiowüstite in former oceanic crust material subducted into the uppermost lower mantle.

A Breakthrough in Pressure Generation by a Kawai-Type Multi-Anvil Apparatus with Tungsten Carbide Anvils

Expansion of the pressure range of Kawai-type multi-anvil presses (KMAPs) with tungsten carbide (WC) anvils is called for, especially in the field of Earth science. However, no significant progress in pressure generation has been made for 40 years. Our recent studies have expanded the pressure generation of a KMAP with WC anvils to 65 GPa, which is the world record for high-pressure generation in this device and is more than 2.5 times higher than conventional pressure generation. We have also successfully generated pressures of about 50 GPa at high temperatures. This work reviews our recently developed technology for high-pressure generation. High-pressure generation at room temperature and at high temperature was attained by integration of the following techniques: ① a precisely aligned guide-block system, ② a high degree of hardness of the second-stage anvils, ③ tapering of the second-stage anvil faces, ④ a high-pressure cell consisting of materials with a high bulk modulus, and ⑤ high thermal insulation of the furnace. Our high-pressure technology will facilitate investigation of the phase stability and physical properties of materials under the conditions of the upper part of the lower mantle, and will permit the synthesis and characterization of novel materials.

Stability of the hydrous phases of Al-rich phase D and Al-rich phase H in deep subducted oceanic crust

To understand the stability of hydrous phases in mafic oceanic crust under deep subduction conditions, high-pressure and high-temperature experiments were conducted on two hydrous basalts using a Kawai-type multi-anvil apparatus at 17–26 GPa and 800–1200 °C. In contrast to previous studies on hydrous basalt that reported no hydrous phases in this pressure range, we found one or two hydrous phases in all run products at or below 1000 °C. Three hydrous phases, including Fe-Ti oxyhydroxide, Al-rich phase D and Al-rich phase H, were present at the investigated P-T conditions. At T ≤ 1000 °C, Fe-Ti oxyhydroxide is stable at 17 GPa, Al-rich phase D is stable at 18–23 GPa, and Al-rich phase H is stable at 25–26 GPa. Our results, in combination with published data on the stability of hydrous phases at lower pressures, suggest that a continuous chain of hydrous phases may exist in subducting cold oceanic crust (≤1000 °C): lawsonite (0–8 GPa), Fe-Ti oxyhydroxide (8–17 GPa), Al-rich phase D (18–23 GPa), and Al-rich phase H (>23 GPa). Therefore, in cold subduction zones, mafic oceanic crust, in addition to peridotite, may also carry a substantial amount of water into the mantle transition zone and the lower mantle.

High pressure generation in Kawai-type multianvil apparatus using nano-polycrystalline diamond anvils

Nano-polycrystalline diamond cubes with an edge length of 6mm have been used as anvils for Kawai-type multianvil apparatus. The maximum pressure of ∼88GPa was confirmed based on in situ X-ray diffraction measurements using nano-polycrystalline diamond anvils with a truncation of 1.0mm, which is more than 50% higher than the pressure (∼56GPa) achieved at the same press load using sintered-diamond anvils. The X-ray transparency of the nano-polycrystalline diamond anvil was found to be about 10–100 times as high as that of sintered-diamond anvils for a wide range of photon energies (∼30–130keV), leading to high-quality X-ray imaging and diffraction profiles of the sample under pressure, even through the anvils. It is expected that further optimization of the pressure medium and gasket would lead to pressures far higher than 100GPa without sacrificing the advantages of the multianvil apparatus over diamond anvil cells.

High-pressure generation in the Kawai-type multianvil apparatus equipped with tungsten-carbide anvils and sintered-diamond anvils, and X-ray observation on CaSnO3 and (Mg,Fe)SiO3

We extended the attainable pressure of the Kawai-type multianvil apparatus to 71.3GPa and 120.3GPa at room temperature by equipping it with tungsten carbide (WC) and sintered diamond (SD) cubic anvils, respectively. In the experiments with WC anvils, pressure decreased largely, ΔP ∼−20GPa, on heating from room temperature to 1500K. In the experiments with SD anvils, pressure also dropped to 105GPa from 120GPa at 1673K. In order to generate higher pressure and temperatures, therefore, innovation of SD material in both quality and size are essential, together with improvements of cell assembly. Besides pressure generation, we conducted in situ energy-dispersive X-ray diffraction observations on CaSnO3 and (Mg,Fe)SiO3 in the experiments with WC and SD anvils, respectively. We observed the growth of new peaks, which can be assigned to the post-perovskite phase, transformed from a starting material of CaSnO3 perovskite at 48.4GPa and 1500K, although they are not clearly identified. In contrast, we could not observe the post-perovskite phase of (Mg,Fe)SiO3 in the present P–T conditions generated by experiments with SD anvils.

Effects of pressure and water on electrical conductivity of carbonate melt with implications for conductivity anomaly in continental mantle lithosphere

The electrical conductivity of Na, Mg-bearing carbonate melts was measured in a Kawai-type multi-anvil apparatus as a function of pressure. The carbonate samples were mixtures of MgCO3 and Na2CO3 or Mg5(CO3)4(OH)2·4(H2O) and Na2CO3. High-pressure experiments on the carbonate systems were performed up to 1800 K in a wide pressure range from 3.4 to 10.9 GPa. The sample conductivity abruptly changed at the eutectic temperature, which increased with increasing pressure. The hydrous carbonate yielded a lower eutectic temperature than the anhydrous carbonate and showed weaker pressure dependence. The molten state carbonates showed very high electrical conductivity with temperature dependence following the Arrhenius law. As the pressure increased, the conductivity decreased. The negative pressure dependence of the electrical conductivity of the hydrous carbonate melt was larger than that of the anhydrous one. The activation volumes were ΔV = 1.81 and 3.61 cm mol−1 for the anhydrous and hydrous carbonate melts, respectively. The high electrical conductivity observed in the mantle beneath the Slave and Brazilian cratons can be explained by the process of lithospheric rejuvenation due to a small amount of hydrous carbonated melt released from the crystallization of the kimberlitic magma at the base of the continental mantle lithosphere.

Negative activation volume of oxygen self-diffusion in forsterite

Oxygen self-diffusion coefficients (DOx) were measured in single crystals of dry synthetic iron-free olivine (forsterite, Mg2SiO4) at a temperature of 1600 K and under pressures in the range 10−4 to 13 GPa, using a Kawai-type multi-anvil apparatus and an ambient pressure furnace. Diffusion profiles were obtained by secondary ion mass spectrometry operating in depth profiling mode. DOx in forsterite increases with increasing pressure with an activation volume of −3.9 ± 1.2 cm3/mol. Although Mg is the fastest diffusing species in forsterite under low-pressure conditions, O is the fastest diffusing species at pressures greater than ∼10 GPa. Si is the slowest throughout the stable pressure range of forsterite. Based on the observed positive and negative pressure dependence of DOx and DMg (Mg self-diffusion coefficient), respectively, DOx + DMg in forsterite decreases with increasing pressure, and then increases slightly at pressures greater than 10 GPa. This behavior is in agreement with the pressure dependence of ionic conductivity in forsterite based on conductivity measurements (Yoshino et al., 2017), and can be used to explain the conductivity increase from ∼300 km depth to the bottom of the asthenosphere.

Phase relations and mineral chemistry in pyrolitic mantle at 1600–2200 °C under pressures up to the uppermost lower mantle: Phase transitions around the 660-km discontinuity and dynamics of upwelling hot plumes

We determined phase relations of pyrolite at 12–28 GPa and 1600–2200 °C using a 6–8 Kawai-type multianvil apparatus. A large number of high pressure and high temperature experiments were conducted to constrain the phase relations especially around 660-km depth, compared with previous studies. The phase relations drastically change between 19 and 23 GPa with temperature as follows. At 19–22 GPa, a phase transition of ringwoodite (Rw) to garnet (Gt) + magnesiowüstite (Mw) occurs at 1800 °C, and no Rw is observed at 2200 °C. The mineral proportion of Gt increases with increasing temperature due to this decomposition reaction and becomes larger than that of Rw above 1800 °C. At 23 GPa, pyrolite crystallizes to a mineral assemblage of bridgmanite (Bm) + Mw + Gt + calcium perovskite by the post-spinel (pSp) transition at 1600–2000 °C and the post-garnet (pGt) transition at 2100–2200 °C, the latter of which is defined as a phase transition of a part of Gt to Bm. Clapeyron slopes of the pSp transition and the pGt transition are determined to be −1 and 5 MPa/°C, respectively, in this study. Gt is stable at any temperatures around the 660-km discontinuity (D660), and Gt-disappearance reaction occurs at 25 GPa with no temperature dependence. Densities of pyrolite were calculated in various pressure and temperature conditions by using the mineral proportions and available data of equations of state. The density at 1600 °C is higher than that at 1800–2200 °C at any pressure-temperature conditions in this study. In particular, the drastic density drop occurs at 19–24 GPa between 1600 and 1800–2200 °C because of increase of Gt proportion with increasing temperature. These suggest that upwelling hot plumes composed of pyrolite from the lower mantle do not stagnate and their ascent is promoted across D660. The mineral proportions and the density changes also suggest that the phase transition which causes D660 changes around 1800 °C from the pSp to the pGt transitions because of the mineral proportion inversion between Rw and Gt.