Nano-polycrystalline Diamond Anvils Research Articles

Improvement of nano-polycrystalline diamond anvil cells with Zr-based bulk metallic glass cylinder for higher pressures: application to Laue-TOF diffractometer

ABSTRACT Single-crystal neutron diffraction provides direct information about crystal structures such as hydrogen positions and magnetic structures. However, in-situ experiments conducted under high pressure entail technical difficulties such as attenuation correction, masking of parasitic diffraction, and limitations of sample volumes and accessible directions. For this study, we improved diamond anvil cells with a tubular frame made of Zr-based bulk metallic glass and nano-polycrystalline diamond anvils for single-crystal neutron diffraction. The thicker tubular frame was confirmed through experimentation as stably generating 4.5 GPa. Its feasibility for neutron diffraction was assessed at the Laue-TOF diffractometer at the BL18 (SENJU) beamline in the MLF J-PARC using time-resolved two-dimensional detectors covering wide solid angles. In addition to ambient-pressure measurements of NH4Cl, diffraction patterns of a high-pressure phase of ice were also collected in-situ. The obtained intensities are of refinable quality sufficient for structure analysis.

A new internally heated diamond anvil cell system for time-resolved optical and x-ray measurements

We have developed a new internally heated diamond anvil cell (DAC) system for in situ high-pressure and high-temperature x-ray and optical experiments. We have adopted a self-heating W/Re gasket design allowing for both sample confinement and heating. This solution has been seldom used in the past but proved to be very efficient to reduce the size of the heating spot near the sample region, improving heating and cooling rates as compared to other resistive heating strategies. The system has been widely tested under high-temperature conditions by performing several thermal emission measurements. A robust relationship between electric power and average sample temperature inside the DAC has been established up to about 1500 K by a measurement campaign on different simple substances. A micro-Raman spectrometer was used for various in situ optical measurements and allowed us to map the temperature distribution of the sample. The distribution resulted to be uniform within the typical uncertainty of these measurements (5% at 1000 K). The high-temperature performances of the DAC were also verified in a series of XAS (x-ray absorption spectroscopy) experiments using both nano-polycrystalline and single-crystal diamond anvils. XAS measurements of germanium at 3.5 GPa were obtained in the 300 K-1300 K range, studying the melting transition and nucleation to the crystal phase. The achievable heating and cooling rates of the DAC were studied exploiting a XAS dispersive setup, collecting series of near-edge XAS spectra with sub-second time resolution. An original XAS-based dynamical temperature calibration procedure was developed and used to monitor the sample and diamond temperatures during the application of constant power cycles, indicating that heating and cooling rates in the 100 K/s range can be easily achieved using this device.

Developments of nano-polycrystalline diamond anvil cells for neutron diffraction experiments

ABSTRACTA new high pressure cell for neutron diffraction experiments using nano-polycrystalline anvils is presented. The cell design, off-line pressure generation tests and a gas-loading procedure for this cell are described. The performance is illustrated by powder neutron diffraction patterns of ice VII to ∼82 GPa. We also demonstrate the feasibility of single crystal neutron diffraction experiments of Fe3O4 at ambient conditions using this cell and discuss the current limitation and future developments.

Recent progress in high pressure X-ray absorption spectroscopy studies at the ODE beamline

ABSTRACTHigh pressure energy-dispersive X-ray absorption spectroscopy is a valuable structural technique, especially, when combined with a nano-polycrystalline diamond anvil cell. Here we present recent results obtained using the dispersive setup of the ODE beamline at SOLEIL synchrotron. The effect of pressure and temperature on the X-ray induced photoreduction is discussed on the example of nanocrystalline CuO. The possibility to follow local environment changes during pressure-induced phase transitions is demonstrated for α-MoO based on the reverse Monte Carlo simulations.

A nano-polycrystalline diamond anvil cell with bulk metallic glass cylinder for single-crystal neutron diffraction

ABSTRACTA high-pressure cell for in-situ single-crystal neutron diffraction was developed. The cell uses nano-polycrystalline diamond anvils in a tubular load frame made of bulk metallic glass which is highly transparent to neutrons and does not produce Bragg reflections. Diffraction peaks from a sample can be measured from almost any direction and the simple geometry of the cell allows accurate attenuation corrections. We demonstrate the operation of the cell by ambient-pressure experiment using a single-crystal of NaCl on the D9 diffractometer at the Institute-Laue-Langevin. A high-pressure experiment was also carried out on a single crystal of ice VII at 2.35 GPa showing the potential to detect weak diffraction spots. The correct integration of weak reflections together with the simple attenuation correction will help to carry out precise structure analysis and address new scientific problems using neutron diffraction.

Nano-polycrystalline diamond anvils: key devices for XAS at extreme conditions: their use, scientific impact, present status and future needs

ABSTRACTNano-polycrystalline diamonds (NPDs) have become fundamental tools for cutting-edge X-ray absorption spectroscopy (XAS) studies at high P/T conditions that opened up new research directions by overcoming previous limitations. Indeed, NPDs yield a continuous and weak X-ray background signal which enables the collection of high-quality XAS data of materials compressed in diamond anvil cells. This is a critical advantage over the classically used single-crystal diamonds that generate strong parasitic signals (glitches) which render the analysis of XAS data in many cases impossible. In this contribution we give an overview of the impact and the scientific opportunities that NPDs opened up for extreme condition XAS spectroscopy at the European Synchrotron Radiation Facility and discuss future needs.

High pressure atomic structure of Zr–Cu metallic glass via EXAFS spectroscopy and molecular dynamics simulations

ABSTRACTIn this work, we use extended X-ray absorption fine structure (EXAFS) data collected using nano-polycrystalline diamond anvil cell to study the atomic arrangement in Zr–Cu metallic glass in high pressure (HP) conditions. To reveal the microscopic details of stress accommodation mechanism, we performed molecular dynamics (MD) simulations of the HP atomic arrangement. By comparing the experimental and the calculated Zr and Cu K-edge EXAFS signal we prove the realistic character of the computer simulations. A detailed geometrical analysis of the simulated atomic configurations shows that with increasing hydrostatic pressure the local structure of Zr–Cu amorphous alloy becomes gradually dominated by Cu-centred icosahedral structural motifs involving fivefold symmetry incompatible with crystalline ordering. The variation of the short-range order is attributed to preferential straining of mechanically soft bonds between zirconium atoms.

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.

Pressure-Induced Superconductivity in Sulfur-Doped SnSe Single Crystal Using Boron-Doped Diamond Electrode-Prefabricated Diamond Anvil Cell

Sulfur-doped SnSe single crystal was successfully synthesized using a melt and slow-cooling method. The chemical composition and valence state of the obtained sample were analyzed by X-ray photoelectron spectroscopy. The pressure range of a diamond anvil cell with boron-doped diamond electrodes was upgraded to 104 GPa using nano-polycrystalline diamond anvil to investigate a pressure effect for the sample. Electrical resistivity measurements of sulfur-doped SnSe single crystal showed the insulator-metal-superconductor transition by applying high pressure up to 75.9 GPa.

Bond compressibility and bond Grüneisen parameters of CdTe

Extended x-ray absorption fine structure (EXAFS) at the Cd K edge and diffraction patterns have been measured on CdTe as a function of pressure from 100 kPa (1 bar) to 5 GPa using a cell with nano-polycrystalline diamond anvils and an x-ray focussing scanning spectrometer. Three phases—zincblende (ZB), mixed cinnabar-ZB and rocksalt (RS)—are well distinguished in different pressure intervals. The bond compressibility measured by EXAFS in the ZB phase is slightly smaller than the one measured by diffraction and decreases significantly faster when the pressure increases; the difference is attributed to the effect of relative vibrations perpendicular to the Cd–Te bond. The parallel mean square relative displacement (MSRD) decreases, the perpendicular MSRD increases when the pressure increases, leading to an increasing anisotropy of relative atomic vibrations. A constant-temperature bond Grüneisen parameter (GP) has been evaluated for the ZB phase and compared with the constant-pressure bond GP measured in a previous experiment; an attempt is made to connect the bond GPs measured by EXAFS and the more familiar thermodynamic GP and mode GPs; the comparisons suggest the inadequacy of the quasi-harmonic approximation to deal with the local vibrational properties sampled by EXAFS.

High-pressure rotational deformation apparatus to 135 GPa.

A large-strain, torsional deformation apparatus has been developed based on diamond anvil cells at high pressures, up to 135 GPa with a help of hard nano-polycrystalline diamond anvils. These pressure conditions correspond to the base of the Earth's mantle. An X-ray laminography technique is introduced for high-pressure in situ 3D observations of the strain markers. The technique developed in this study introduces the possibility of the in situ rheological measurements of the deep Earth materials under ultrahigh-pressure conditions.

Diamond anvil cell using metallic diamond electrodes

A novel diamond anvil cell specialized for resistivity measurements under high pressure have been developed. Boron-doped metallic diamond electrodes were deposited onto a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The various designs of boron-doped metallic diamond electrodes were demonstrated, and they showed no signs of degradation after repeated compression.

Applications of nano-polycrystalline diamond anvils to X-ray absorption spectroscopy under high pressure

ABSTRACTRecently, nano-polycrystalline diamond (NPD) anvils have been widely applied in high pressure research using X-ray absorption spectroscopy (XAS). The nanometer-sized polycrystallization in NPD anvils enables us to obtain glitch-free X-ray absorption spectra. This advantage of NPD anvils drastically improves the experimental conditions of XAS, which has previously used conventional single-crystal diamond (SCD) anvils. Distorted spectra due to the glitches from the SCD anvils have been an inevitable problem of XAS. This paper reviews recent studies of XAS and related spectroscopic techniques using the NPD anvils, which have mainly been performed on BL39XU of SPring-8. We demonstrate how NPD anvils are useful when using XAS for high pressure research.

Note: Novel diamond anvil cell for electrical measurements using boron-doped metallic diamond electrodes.

A novel diamond anvil cell suitable for electrical transport measurements under high pressure has been developed. A boron-doped metallic diamond film was deposited as an electrode on a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The maximum pressure that can be achieved by this assembly is above 30 GPa. We report electrical transport measurements of Pb up to 8 GPa. The boron-doped metallic diamond electrodes showed no signs of degradation after repeated compression.

Glitch-free X-ray absorption spectrum under high pressure obtained using nano-polycrystalline diamond anvils.

Nano-polycrystalline diamond (NPD) [Irifune et al. (2003), Nature (London), 421, 599] has been used to obtain a glitch-free X-ray absorption spectrum under high pressure. In the case of conventional single-crystal diamond (SCD) anvils, glitches owing to Bragg diffraction from the anvils are superimposed on X-ray absorption spectra. The glitch has long been a serious problem for high-pressure research activities using X-ray spectroscopy because of the difficulties of its complete removal. It is demonstrated that NPD is one of the best candidate materials to overcome this problem. Here a glitch-free absorption spectrum using the NPD anvils over a wide energy range is shown. The advantage and capability of NPD anvils is discussed by a comparison of the glitch map with that of SCD anvils.

Application of Nano-Polycrystalline Diamond (NPD) to DAC

Nano-polycrystalline diamond (NPD), consisting of nano-sized diamond grains oriented in random directions without containing any secondary phases, can be produced by direct conversion sintering from graphite under high pressure and high temperature. NPD is characterized by high hardness surpassing that of single crystal diamond, and exhibits no cleavage features and has isotropy of mechanical properties. These characteristics of NPD suggest potential applications of this novel material as anvils for diamond anvil cells. In this article, some properties of NPD and results of high-pressure generation tests using NPD anvils are reviewed, and its potentiality as a new anvil material is discussed.

Large-volume static compression using nano-polycrystalline diamond for opposed anvils in compact cells

In order to extend the pressure regime of intrinsically low-sensitivity methods of measurement, such as neutron scattering and NMR, sample volume to be compressed in compact opposed-anvil cells is desired to be significantly increased. We hereby conducted a series of experiments using two types of compact cells equipped with enforced loading mechanisms. Super-hard nano-polycrystalline diamond (NPD) anvils were carefully prepared for large-volume compression in these cells. These anvils are harder, larger and stronger than single crystal diamond anvils, so that they could play an ideal role to accept the larger forces. Supported and unsupported anvil geometries were separately tested to evaluate this expectation. In spite of insufficient support to the anvils, pressures to 14 GPa were generated for the sample volume of > 0.1 mm3, without damaging the NPD anvils. These results demonstrate a large future potential of compact cells equipped with NPD anvils and enforced loading mechanism.

Pressure generation up to 55 GPa using a Drickamer-type apparatus with sintered diamond anvils toward use of nano-polycrystalline diamond as anvils

Pressure calibration experiments were performed at room temperature for a Drickamer-type apparatus using a composite anvil system with a sintered diamond anvil, which can be replaced by nano-polycrystalline diamond anvil. The culet diameter and tapering angle are 1.0 mm and 30°, respectively. Transitions in Fe2O3 (50 GPa) and CoO (55 GPa) were observed at 39.6 and 38.5 kN, respectively, by electrical resistance measurements. Pressure of about 120 GPa can be generated at the maximum load of 98 kN by assuming the linear extrapolation of the obtained load-pressure relation. The Drickamer-type apparatus with nano-polycrystalline diamond anvils has potential to generate pressure covering the whole lower mantle.

Laser heating in nano-polycrystalline diamond anvil cell

Laser heating in a diamond anvil cell equipped with nano-polycrystalline diamond anvils (NPDAC) was tested for the first time. NPDAC was found to provide better heating efficiency than the standard DAC with single crystal anvils. This is probably attributed to an order of magnitude lower thermal conductivity of the NPD. High-temperature generation exceeding 4500 K was observed during laser heating of hcp-iron sample at pressure of ~100 GPa. The present study demonstrates a promising potential of laser-heated NPDAC for generation of ultra-high temperature under multi-megabar pressure conditions equivalent to those of the Earth's core.

Application of nano-polycrystalline diamond to laser-heated diamond anvil cell experiments

Laser heating in diamond anvil cell (DAC) equipped with nano-polycrystalline diamond (NPD) anvils was tested for the first time using various types of lasers. An NPD-based DAC was found to provide better heating efficiency than a standard DAC with single-crystal anvils, probably due to the order of magnitude lower thermal conductivity of the NPD. We observed high-temperature generation exceeding 5000 and 3500 K during laser heating of hcp-Fe sample at pressures of ∼100 and ∼170 GPa, respectively. The results of the present study demonstrate promising potential of laser-heated nano-polycrystalline DAC for the generation of very high temperature under multi-megabar pressure conditions equivalent to those of the Earth's core.