Diamond Anvil Research Articles

The Thermal Conductivity of Bridgmanite at Lower Mantle Conditions Using a Multi‐Technique Approach

AbstractThe thermal conductivity of bridgmanite, the primary constituent of the Earth's lower mantle, has been investigated using diamond anvil cells at pressures up to 85 GPa and temperatures up to 3,100 K. We report the results of time‐domain optical laser flash heating and X‐ray Free Electron Laser heating experiments from a variety of bridgmanite samples with different Al and Fe contents. The results demonstrate that Fe or Fe,Al incorporation in bridgmanite reduces thermal conductivity by about 50% in comparison to end‐member MgSiO3 at the pressure‐temperature conditions of Earth's lower mantle. The effect of temperature on the thermal conductivity at 28–60 GPa is moderate, well described as , where a is 0.2–0.5. The results yield thermal conductivity of 7.5–15 W/(m × K) in the thermal boundary layer of the lowermost mantle composed of Fe,Al‐bearing bridgmanite.

High Sodium Solubility in Magnesiowüstite in Iron‐Rich Deep Lower Mantle

Abstract(Mg,Fe)O ferropericlase‐magnesiowüstite has been proposed to host the majority of Earth's sodium, but the mechanism and capacity for incorporating the alkali cation remain unclear. In this work, experiments in the laser‐heated diamond anvil cell and first‐principles calculations determine the solubility of sodium and favorability of sodium incorporation in iron‐rich magnesiowüstite relative to (Mg,Fe)SiO3 bridgmanite. Reaction of Mg/(Mg + Fe) (Mg#) 55 and 28 olivine with NaCl at 33–128 GPa and 1600–3000 K produces iron‐rich magnesiowüstite containing several percent sodium, while iron‐rich bridgmanite contains little to no detectable sodium. In sodium‐saturated magnesiowüstite, sodium number [Na/(Na + Mg + Fe)] is 2–5 atomic percent at pressures below 60 GPa and drastically increases to 10–20 atomic percent at deep lower mantle pressures. For these two compositions, there is no significant dependence of the results on Mg#. Our calculations not only show consistent results with experiments but further indicate that such an increase in solubility and partitioning of Na into magnesiowüstite is driven by the spin transition in iron. These results provide fundamental constraints on the crystal chemistry of sodium at lower‐mantle conditions. If the sodium capacity of (Mg,Fe)O is not strongly dependent on Mg#, (Mg,Fe)O in the lower mantle may have the capacity to store the entire sodium budget of the Earth.

High-pressure phase transitions of Fe-bearing orthopyroxene revealed by Raman spectroscopy

Abstract Orthopyroxene is one of the dominant minerals in the Earth’s upper mantle. In this study, we used Raman spectroscopy to investigate the lattice vibration and phase transition of orthopyroxene with four different compositions using diamond-anvil cells up to 34 GPa at 300 K. Our orthopyroxene samples contain 0 (En100), 9% (En91Fs9), 11% (En86Fs11), and 21% (En74Fs21) Fe. At ambient conditions, the Raman modes exhibit a negative dependence on the Fe content, with the exception of the modes at ~850 and 930 cm–1. In contrast, these two Raman modes increase with increasing the Fe content. The phase transition from metastable α- to β-phase was observed at 12.9–15 GPa for samples with <21 mol% Fe and varying Fe content has a minor effect on the phase transition pressure. Besides Fe, incorporation of 2–24 mol% Al can cause an increase in the phase transition pressure from 10–13 to 14–16 GPa. At 29–30.1 GPa, we observed the second apparent change in the Raman spectra for all four investigated samples. For Fe-bearing orthopyroxene, this change in the Raman spectra and frequency shift is associated with the phase transition from β- to γ-phase, whereas for En100, it should be caused by the change of coordination number of Si from 4 to 6 or the presence of α-popx phase. Using the obtained Raman frequency shifts, we calculated the Grüneisen parameters at high pressures. These parameters are useful for understanding the thermoelastic properties of orthopyroxene at high pressures.

Hydrolysis rate constants of ATP up to 120 °C and 1.6 GPa: Implications for life at extreme conditions

Extreme environments are habitats for a diverse array of microorganisms, namely extremophiles, that have evolved unique biochemical adaptations to their geological setting. Some examples of extremophiles can be found in the subseafloor or near hydrothermal vents on the ocean floor. Cultivated strains of extremophiles have demonstrated the ability to tolerate temperatures (T) up to 122 °C and pressures (P) up to 125 MPa. Organisms depend on the stability of key metabolites, such as adenosine triphosphate (ATP), to survive and reproduce under these conditions. In order to maintain their intracellular ATP levels, living cells must compensate for the abiotic hydrolysis of ATP, which occurs at a particularly rapid rate at high temperatures. The role of high pressures and high temperatures in abiotic hydrolysis of ATP has been rarely investigated despite the potential for this phenomenon to contribute to limit the adaptation of microorganisms to simultaneous extreme temperatures and pressures. This study presents new data on the effect of pressure on the abiotic hydrolysis of ATP to adenosine diphosphate (ADP) at elevated temperatures. In situ Raman spectra were measured at high pressure and high temperature of the hydrolysis of aqueous disodium ATP solutions in two experimental systems: a hydrothermal diamond anvil cell (HDAC) and a gas-pressurized autoclave. These two systems permitted the determination of hydrolysis rate constants of ATP into ADP up to 1670 MPa at 80 °C, 100 °C, and 120 °C. The data exhibited Arrhenian behavior with a slight decrease in activation energy from 0.5 MPa to 140 MPa. The effect of pressure on ATP hydrolysis rate constants was found to be vanishingly low in the so far known vital range up to 125 MPa. Abiotic hydrolysis rates of ATP showed a pronounced increase at higher pressures. For example, at 100 °C, a rise in pressure from 365 MPa to approximately 1670 MPa results in a nearly tenfold increase in the ATP hydrolysis rate constant. When compared with the typical ATP turnover times reported in living cells, the abiotic ATP hydrolysis rates determined in this study provide insights into the pressure and temperature conditions that could be consistent with living microorganisms.

Compressibility Studies of Copper Selenides Obtained by Cation Exchange Reaction Revealing the New CsCl Phase.

In this study, we conducted a high-pressure investigation of Cu2-xSe nanostructures with pyramid- and plate-like morphologies, created through cation exchange from zinc-blende CdSe nanocrystals and wurtzite CdSe nanoplatelets respectively. Using a diamond anvil cell setup at the APS synchrotron, we observed the phase transitions in the Cu2-xSe nanostructures up to 40 GPa, identifying a novel CsCl-type lattice with Pm3̅m symmetry above 4 GPa. This CsCl-type structure, previously unreported in copper selenides, was partially retained after decompression. Our results indicate that the initial crystalline structure of CdSe does not affect the stability of Cu2-xSe nanostructures formed via cation exchange. Both morphologies of Cu2-xSe sintered under compression, potentially contributing to the stabilization of the high-pressure phase through interfacial defects. These findings are significant for discovering new phases with potential applications in future technologies.

Time‐resolved Raman spectroscopy study of rapid compressed silicon and its potential as a Raman pressure scale in a dynamic diamond anvil cell

AbstractThe nature of the nonequilibrium states of materials upon rapid compression/decompression processes in the intermediate regime, between static and shock compression, is an emerging field of high pressure research. Rapid compression experiments were performed to examine the structural response of silicon (Si) up to 11 GPa and over compression rates ranging from 0.011 to 0.325 GPa/s, using a piezo‐driven dynamic diamond anvil cell (dDAC) coupled with time‐resolved Raman spectroscopy. The observed structural stability and the remarkable consistency in the pressure‐dependent Raman shift of the diamond cubic Si (Si‐I) showed its high potential as a Raman pressure scale for compression rate below 0.325 GPa/s. The validity of the derived Si scale was verified by in situ continuously monitoring pressure of two rapid compressed samples, that is, gypsum and ZnO. Results indicated that pressures determined using Si were in good agreement with those estimated from the ruby scale. Success in pressure calibration with Si, during time‐resolved Raman spectroscopy measurements of material under rapid compression using a dDAC, will greatly simplify the required hardware system in home‐laboratory and may also help in reaching a higher signal‐to‐noise in Raman measurement on a short time scale.

Photoluminescence and light absorption edges of Bi2O2CO3 regulated by pressure-induced oxygen vacancies

In this work, Bi2O2CO3 (BOC) was subjected to high-pressure treatment using a diamond anvil cell at pressures of 0, 4.2, and 25.6 GPa to improve the photocatalytic performance. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were employed for in-depth analysis. The results indicated that after treatment at 25.6 GPa, oxygen vacancies were induced in the powder, and defect energy levels were formed within the band gap of the BOC, thereby expanding its absorption of visible light. The light absorption edge shifted from 377 nm to 562 nm, which have enhanced the ability of separating photogenerated electron-hole pairs. This study demonstrates that high-pressure treatment is beneficial for improving the photocatalytic performance of Bi2O2CO3.

Pressure stabilizes ferrous iron in bridgmanite under hydrous deep lower mantle conditions

Earth’s lower mantle is a potential water reservoir. The physical and chemical properties of the region are in part controlled by the Fe3+/ΣFe ratio and total iron content in bridgmanite. However, the water effect on the chemistry of bridgmanite remains unclear. We carry out laser-heated diamond anvil cell experiments under hydrous conditions and observe dominant Fe2+ in bridgmanite (Mg, Fe)SiO3 above 105 GPa under the normal geotherm conditions corresponding to depth > 2300 km, whereas Fe3+-rich bridgmanite is obtained at lower pressures. We further observe FeO in coexistence with hydrous NiAs-type SiO2 under similar conditions, indicating that the stability of ferrous iron is a combined result of H2O effect and high pressure. The stability of ferrous iron in bridgmanite under hydrous conditions would provide an explanation for the nature of the low-shear-velocity anomalies in the deep lower mantle. In addition, entrainment from a hydrous dense layer may influence mantle plume dynamics and contribute to variations in the redox conditions of the mantle.

Exploring toroidal anvil profiles for larger sample volumes above 4 Mbar.

With the advent of toroidal and double-stage diamond anvil cells (DACs), pressures between 4 and 10 Mbar can be achieved under static compression, however, the ability to explore diverse sample assemblies is limited on these micron-scale anvils. Adapting the toroidal DAC to support larger sample volumes offers expanded capabilities in physics, chemistry, and planetary science: including, characterizing materials in soft pressure media to multi-megabar pressures, synthesizing novel phases, and probing planetary assemblages at the interior pressures and temperatures of super-Earths and sub-Neptunes. Here we have continued the exploration of larger toroidal DAC profiles by iteratively testing various torus and shoulder depths with central culet diameters in the 30-50µm range. We present a 30µm culet profile that reached a maximum pressure of 414(1) GPa based on a Pt scale. The 300K equations of state fit to our P-V data collected on gold and rhenium are compatible with extrapolated hydrostatic equations of state within 1% up to 4 Mbar. This work validates the performance of these large-culet toroidal anvils to > 4 Mbar and provides a promising foundation to develop toroidal DACs for diverse sample loading and laser heating.

Nitrogen sequestration in the core at megabar pressure and implications for terrestrial accretion

Nitrogen (N) is the most abundant element in Earth’s atmosphere, but is extremely depleted in the silicate Earth. However, it is not clear whether core sequestration or early atmospheric loss was responsible for this depletion. Here we study the effect of core formation on the inventory of nitrogen using laser-heated diamond anvil cells. We find that, due to the simultaneous dissolution of oxygen in the metal, N becomes much less siderophile (iron-loving) at pressures and temperatures up to 104 GPa and 5000 K, a thermodynamic condition relevant to the bottom of the magma ocean in the aftermath of the moon-forming giant impact. Using a core–mantle–atmosphere coevolution model, we show that the impact-induced processes (core formation and/or atmospheric loss) are unlikely to account for the observed N anomaly, which is instead best explained by the accretion of mainly N-poor impactors. The terrestrial volatile pattern requires severe N depletion on precursor bodies, prior to their accretion to the proto-Earth.

High‐Pressure Synthesis of Ultra‐Incompressible, Hard and Superconducting Tungsten Nitrides

AbstractTransition metal nitrides, particularly those of 5d metals, are known for their outstanding properties, often relevant for industrial applications. Among these metal elements, tungsten is especially attractive given its low cost. In this high‐pressure investigation of the W–N system, two novel ultra‐incompressible tungsten nitride superconductors, namely W2N3 and W3N5, are successfully synthesized at 35 and 56 GPa, respectively, through a direct reaction between N2 and W in laser‐heated diamond anvil cells. Their crystal structure is determined using synchrotron single‐crystal X‐ray diffraction. While the W2N3 solid's sole constituting nitrogen species are N3‐ units, W3N5 features both discrete N3‐ as well as N24‐ pernitride anions. The bulk modulus of W2N3 and W3N5 is experimentally determined to be 380(3) and 406(7) GPa, and their ultra‐incompressible behavior is rationalized by their constituting WN7 polyhedra and their linkages. Importantly, both W2N3 and W3N5 are recoverable to ambient conditions and stable in air. Density functional theory calculations reveal W2N3 and W3N5 to have a Vickers hardness of 30 and 34 GPa, and superconducting transition temperatures at ambient pressure (50 GPa) of 11.6 K (9.8 K) and 9.4 K (7.2 K), respectively. Additionally, transport measurements performed at 50 GPa on W2N3 corroborate with the calculations.

Trapped flux in a small crystal of CaKFe4As4 at ambient pressure and in a diamond anvil pressure cell

In an extension of our previous work, (Bud’ko et al 2023 Supercond. Sci. Technol. 36 115001) the measurements of temperature dependent magnetization associated with trapped magnetic flux in a small single crystal of CaKFe4As4, using zero—field—cooled and field—cooled protocols were performed, on the same crystal, at ambient pressure without a pressure cell and at 2.2 GPa in a commercial diamond anvil cell (DAC), showing comparable results. The data show that with a proper care and understanding, trapped flux measurements in superconductors indeed can be performed on samples in DACs under pressure, as was done on superhydrides (Minkov et al 2023 Nat. Phys. 19 1293).

Tunable Photocarrier Dynamics in CuS Nanoflakes under Pressure Modulation.

Two-dimensional materials with a unique layered structure have attracted intense attention all around the world due to their extraordinary physical properties. Most importantly, the internal Coulomb coupling can be regulated, and thus electronic transition can be realized by manipulating the interlayer interaction effectively through adding external fields. At present, the properties of two-dimensional materials can be tuned through a variety of methods, such as adding pressure, strain, and electromagnetic fields. For optoelectronic applications, the lifetime of the photogenerated carriers is one of the most crucial parameters for the materials. Here, we demonstrate effective modulation of the optical band gap structure and photocarrier dynamics in CuS nanoflakes by applying hydrostatic pressure via a diamond anvil cell. The peak differential reflection signal shows a linear blueshift with the pressure, suggesting effective tuning of interlayer interaction inside CuS by pressure engineering. The results of transient absorption show that the photocarrier lifetime decreases significantly with pressure, suggesting that the dissociation process of the photogenerated carriers accelerates. It could be contributed to the phase transition or the decrease of the phonon vibration frequency caused by the pressure. Further, Raman spectra reveal the change of Cu-S and S-S bonds after adding pressure, indicating the possible occurrence of structural phase transition. Interestingly, all of the variation modes are reversible after releasing pressure. This work has provided an excellent sight to show the regulation of pressure on the photoelectric properties of CuS, exploring CuS to wider applications that can lead toward the realization of future excitonic and photoelectric devices modulated by high pressure.

Stretchable Tb-Tb Distance Regulates the Piezofluorochromic Behavior of Chiral Tb(III)-MOF upon Compression.

Luminescent chiral Tb-MOF microcrystals with the Tb2(COO)4 subunit indicated strong green mechano-luminescence under compression. Furthermore, piezofluorochromic behavior in the diamond anvil cell was observed, with the intensity tendency of decreasing-increasing-decreasing and a shortened lifetime upon compression, due to the reversible stretchable Tb-Tb interactions. The Tb-Tb distance upon compression was refined through in situ high-pressure X-ray absorption spectra, which was consistent with the tendency of the piezofluorochromic intensity. In situ high-pressure UV-vis absorption spectra, Fourier transform infrared spectra, and powder X-ray diffraction demonstrated the full recovery of Tb-MOF after over 10 GPa compressions due to the semiflexible ligand. This work not only provided an ultrastable Tb-MOF but also illustrated the relationship of the piezofluorochromic behavior with the detailed structural transformation for the first time.

Evolution of structure and spectroscopic properties of a new 1,3-diacetylpyrene polymorph with temperature and pressure.

A new polymorph of 1,3-diacetylpyrene has been obtained from its melt and thoroughly characterized using single-crystal X-ray diffraction, steady-state UV-Vis spectroscopy and periodic density functional theory calculations. Experimental studies covered the temperature range from 90 to 390 K and the pressure range from atmospheric to 4.08 GPa. Optimal sample placement in a diamond anvil cell according to our previously presented methodology ensured over 80% data coverage up to 0.8 Å for a monoclinic sample. Unrestrained Hirshfeld atom refinement of the high-pressure crystal structures was successful and anharmonic behavior of carbonyl oxygen atoms was observed. Unlike the previously characterized polymorph, the structure of 2°AP-β is based on infinite π-stacks of antiparallel 2°AP molecules. 2°AP-β displays piezochromism and piezofluorochromism which are directly related to the variation in interplanar distances within the π-stacking. The importance of weak intermolecular interactions is reflected in the substantial negative thermal expansion coefficient of -55.8 (57) MK-1 in the direction of C-H...O interactions.

High-pressure Phase Transition of Olivine-type Mg2GeO4 to a Metastable Forsterite-III type Structure and their Equation of States

Abstract Germanates are often used as structural analogs of planetary silicates. We have explored the high-pressure phase relations in Mg2GeO4 using diamond anvil cell experiments combined with synchrotron X-ray diffraction and computations based on density functional theory. Upon room temperature compression, forsterite-type Mg2GeO4 remains stable up to 30 GPa. At higher pressures, a phase transition to a forsterite-III type (Cmc21) structure was observed, which remained stable to the peak pressure of 105 GPa. Using a 3rd order Birch Murnaghan fit to the experimental data, we obtained V0 = 305.1 (3) Å3, K0 = 124.6 (14) GPa and K0′ = 3.86 (fixed) for forsterite- and V0 = 263.5 (15) Å3, K0 = 175 (7) GPa and K0′ = 4.2 (fixed) for the forsterite-III type phase. The forsterite-III type structure was found to be metastable when compared to the stable assemblage of perovskite/post-perovskite + MgO, as observed during laser-heating experiments. Understanding the phase relations and physical properties of metastable phases is crucial for studying the mineralogy of impact sites, understanding metastable wedges in subducting slabs and interpreting the results of shock compression experiments.

High pressure study of hydrogen-bonded energetic material 4-nitropyrazole

The study investigates the structural stability of the hydrogen-bonded energetic material 4-nitropyrazole (4-NP, C3H3N3O2) from ambient pressure to 10 GPa at room temperature using diamond anvil cell (DAC) and Raman spectroscopy. Based on the changes observed in the high-pressure Raman spectra, it is proposed that the hydrogen-bonded energetic material 4-NP undergoes a phase transition within the pressure range of 2.7–6.4 GPa. Upon complete pressure release from 10 GPa, the resulting spectrum is consistent with the Raman spectrum observed under ambient pressure, indicating that the phase transition is reversible. Ab initio calculations were used to explain the changes in molecular arrangements and hydrogen-bonded networks. Hirshfeld surfaces and fingerprint plots were used to directly compare the variations in packing patterns and intermolecular interactions. Based on the experimental and calculated results, it is proposed that the phase transition of 4-NP was likely caused by the rearrangements of the hydrogen-bonded networks.

A novel method for determining the resistivity of compressed superconducting materials

The measurement of resistivity in a compressed material within a diamond anvil cell presents significant challenges. The high-pressure experimental setup makes it difficult to directly measure the size changes induced by pressure in the three crystallographic directions of the sample. In this study, we introduce a novel and effective method that addresses these technical challenges. This method is anticipated to offer a valuable foundation for high-pressure investigations on quantum materials, particularly those with anisotropic layered structures.

Stability, Chemical Bonding, and Electron Lone Pair Localization in AsN at High Pressure by Density Functional Theory Calculations.

The covalent bonding framework of crystalline single-bonded cubic AsN, recently synthesized under high pressure and high temperature conditions in a laser-heated diamond anvil cell, is here studied by means of density functional theory calculations and compared to single crystal X-ray diffraction data. The precise localization of the nonbonding electron lone pairs and the determination of their distances and orientations are related to the presence of characteristic structural motifs and space regions of the unit cell dominated by repulsive electronic interactions, with the relative orientation of the electron lone pairs playing a key role in minimizing the energy of the structure. We find that the vibrational modes associated with the expression of the lone pairs are strongly localized, an observation that may have implications for the thermal conductivity of the compound. The results indicate the thermodynamic stability of the experimentally observed structure of AsN above ∼17 GPa, provide a detailed insight into the nature of the chemical bonding network underlying the formation of this compound, and open new perspectives to the design and high pressure synthesis of new pnictogen-based advanced materials for potential applications of energetic and technological relevance.

A broadband pulse amplifier for Joule heating experiments in diamond anvil cells.

Decades of measurements of the thermophysical properties of hot metals show that pulsed Joule heating is an effective method to heat solid and liquid metals that are chemically reactive or difficult to contain. To extend such measurements to hundreds of GPa pressure, pulsed heating methods have recently been integrated with diamond anvil cells. The recent design used a low-side switch and active electrical sensing equipment that was prone to damage and measurement error. Here, we report the design and characterization of new electronics that use a high-side switch and robust, passive electrical sensing equipment. The new pulse amplifier can heat ∼5 to 50 μm diameter metal wires to thousands of kelvin at tens to hundreds of GPa using diamond anvil cells. Pulse durations and peak currents can each be varied over three orders of magnitude, from 5 µs to 10ms and from 0.2 to 200A. The pulse amplifier is integrated with a current probe. Two voltage probes attached to the body of a diamond anvil cell are used to measure voltage in a four-point probe geometry. The accuracy of four-point probe resistance measurements for a dummy sample with 0.1 Ω resistance is typically better than 5% at all times from 2 µs to 10ms after the beginning of the pulse.