Name: an externally-heated diamond anvil cell for synthesis and single-crystal elasticity determination of ice-vii at high pressure-temperature conditions
Uploaded: 2020-06-18T14:45:00.000+00:00
Duration: 7 min 48 s
Description: Watch this Scientific Journal Video about An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions at JoVE.c

We thank&#160;Siheng Wang, Qinxia Wang, Jing Gao, Yingxin Liu for their help with the experiments. This research used resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. GeoSoilEnviroCARS (Sector 13) is supported by NSF-Earth Sciences (EAR-1128799), and the Department of Energy, Geosciences (DE-FG02-94ER14466). The development of EHDAC was supported by Externally-heated Diamond Anvil Cell Experimentation (EH-DANCE) project to B. Chen under Education Outreach and Infrastructure Development (EOID) program&#160;from COMPRES under NSF Cooperative Agreement EAR-1606856. X. Lai acknowledges the support from the start-up funding of China University of Geosciences (Wuhan) (no.162301202618). B. Chen acknowledges the support from the U.S. National Science Foundation (NSF) (EAR-1555388 and EAR-1829273).&#160;&#160;J.S. Zhang acknowledges the support from the U.S. NSF (EAR-1664471, EAR-1646527 and EAR-1847707).

1. Ring heater preparation
<ol>
	<li>Fabricating the ring heater base
	<ol>
		<li>Fabricate the ring heater base by a computer numerical control (CNC) milling machine using pyrophyllite based on the designed 3D model. The dimensions of the heater are 22.30 mm in outer diameter (OD), 8.00 mm in inner diameter (ID) and 2.25 mm in thickness. Sinter the heater base in the furnace at 1523 K for &#62;20 hours.</li>
	</ol>
	</li>
	<li>Wiring
	<ol>
		<li>Cut Pt 10 wt% Rh wire (diameter: 0.01 inch) into 3 equal-length wires (about 44 cm each).</li>
		<li>Carefully wind each Pt/Rh wire through the holes in the heater base, leave about 10 cm wire outside of the heater base for connection to the power supply. When wiring, make sure that the wire is lower than the gutters of the base. If it is higher than the gutter, use a proper flat-head screwdriver to press it down.</li>
		<li>Wind more wires on the 10 cm extension wires to reduce the electrical resistance and thus the temperature of the extension wires during heating.</li>
	</ol>
	</li>
	<li>Adding insulators
	<ol>
		<li>Use two small ceramic electrical insulating sleeves to protect the wires extending outside the ring heater base. Mix cement adhesive (e.g., Resbond 919) with water at a ratio of 100:13. Fix those tubes to the ring heater base using the cement mixture. 
		NOTE: The cement needs 4 hours to be cured at 393 K or 24 hours at room temperature.</li>
		<li>Use the high-temp braid sleeving to protect the outside wires.</li>
		<li>Cut two mica rings using a CO2 laser-cutting machine. To electrically insulate the wire, attach one mica ring to each side of the heater by UHU tac.</li>
	</ol>
	</li>
</ol>
2. EHDAC preparation
<ol>
	<li>Gluing diamonds
	<ol>
		<li>Align the diamonds with backing seats using mounting jigs. Use black epoxy to glue the diamond to the backing seat. The black epoxy should be lower than the girdle of the diamond to leave some space for the high-temperature cement.</li>
	</ol>
	</li>
	<li>Alignment
	<ol>
		<li>Glue mica or place the machined pyrophyllite rings under the seats to insulate the seats and DAC thermally. Put the seats with the diamonds into a BX-90 DAC. Align two diamonds under the optical microscope.</li>
	</ol>
	</li>
	<li>Preparing the sample gasket
	<ol>
		<li>Place the rhenium gasket, which is smaller than the hole of the ring heater, between the two diamonds and pre-indent the gasket to approximately 30-45 &#181;m by gently tightening the four screws of DAC. Drill a hole at the center of the indentation by electrical discharge machine (EDM) or laser micro-drilling machine.</li>
	</ol>
	</li>
	<li>Mounting thermocouple
	<ol>
		<li>Fix two small pieces of mica with the cement mixture on the seat of the piston side of DAC to electrically insulate the thermocouples from the seat. Attach two K-type (Chromega-Alomega 0.005&#39;&#39;) or R-type (87%Platium/13%Rhodium&#8211;Platium, 0.005&#8221;) thermocouples to the piston side of the DAC, ensuring that the tips of the thermocouples touch the diamond and close to the culet of the diamond (about 500 &#181;m away). Finally, use the high-temperature cement mixture to fix the thermocouple position and cover the black epoxy on both sides of the DAC.</li>
	</ol>
	</li>
	<li>Heater placement
	<ol>
		<li>Cut the 2300 &#176;F ceramic tape in the shape of the heater base by CO2 laser drilling machine and place it on both sides of DAC (piston and cylinder sides). If it is very easy to move around, use some UHU tac to fix it.</li>
		<li>Place the heater in the piston side of the BX-90 DAC. Use some 2300 &#176;F ceramic tape to fill the gap between the heater and the wall of the DAC.</li>
	</ol>
	</li>
	<li>Gasket placement
	<ol>
		<li>Clean the sample chamber hole of the gasket using a needle or sharpened toothpick to get rid of the metal fragments introduced by the drilling. Use ultrasonic cleaner to clean the gasket for 5-10 min.</li>
		<li>Put two small balls of adhesive putty (e.g., UHU Tac) around the diamond on the piston side of the DAC to support the gasket. Align the sample chamber hole of the gasket to match the center of culet under the optical microscope.</li>
	</ol>
	</li>
</ol>
3. Synthesizing single-crystal ice-VII by EHDAC
<ol>
	<li>Loading sample
	<ol>
		<li>Load one or more ruby spheres and one piece of gold into the sample chamber.</li>
		<li>Load a drop of distilled water in the sample chamber, close the DAC and compress it by tightening the four screws on the DAC to quickly seal the water in the sample chamber.</li>
	</ol>
	</li>
	<li>Pressurizing sample to obtain powder ice-VII
	<ol>
		<li>Determine the pressure of the sample by measuring the fluorescence of ruby spheres using a Raman spectrometer.</li>
		<li>Carefully compress the sample by turning the four screws and monitor the pressure by ruby florescence until it reaches the stability field of ice-VII (&#62;2 GPa). Watch the sample chamber under the optical microscope during compression. Sometimes the coexistence of water fluid and crystallized ice VI is visible if the pressure is close to the phase boundary of water and ice VI.</li>
		<li>Continue compressing the sample chamber until it reaches the pressure in the stability field of ice-VII. In order to melt the ice-VII later, the target pressure is usually between 2 GPa and 10 GPa at 300 K.</li>
	</ol>
	</li>
	<li>Heating sample to obtain single crystal ice-VII
	<ol>
		<li>Put the EHDAC under the optical microscope with a camera connected to the computer. Thermally insulate the DAC from the microscope stage, without blocking the transmitted light path of the microscope.</li>
		<li>Connect the thermocouple to the thermometer and connect the heater to a DC power supply.</li>
		<li>Monitor the melting of ice-VII crystals upon heating to a temperature that is higher than the melting temperature of high-pressure ice-VII determined by the phase diagram of H2O.</li>
		<li>Quench the sample chamber to allow the liquid water to crystallize, and then increase the temperature until some of the smaller ice crystals are molten. Repeat the heating and cooling cycles a few times until only one or a few larger grains remains in the sample chamber.</li>
		<li>Measure the pressure of the sample after the synthesis.</li>
	</ol>
	</li>
</ol>
4. Synchrotron X-ray diffraction and Brillouin spectroscopy collection
<ol>
	<li>Synchrotron X-ray diffraction
	<ol>
		<li>Check if the ice-VII sample synthesized is polycrystalline or a single crystal by synchrotron-based single-crystal XRD15. If it is a single crystal, the diffraction pattern should be diffraction spots instead of powder rings.</li>
		<li>Obtain step scan single-crystal XRD images to determine the orientation and lattice parameters of ice-VII.</li>
		<li>Collect the XRD of pressure marker, i.e. gold, in the sample chamber to determine the pressure.</li>
	</ol>
	</li>
	<li>Brillouin spectroscopy
	<ol>
		<li>Mount the EHDAC on a specialized holder which can be rotated within the vertical plane by changing the &#967; angles. Connect the thermocouples to the temperature controller and connect the heater to the power supply.</li>
		<li>Perform Brillouin spectroscopy measurements every 10-15&#176; &#967; angle at 300 K for a total &#967; angle range of 180&#176; or 270&#176;16. Then heat the sample to high temperatures (e.g., 500 K) and repeat the Brillouin spectroscopy measurement.</li>
	</ol>
	</li>
</ol>

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The authors declare no conflict of interest.

In this work, we described the protocol of preparing the EHDAC for high pressure research. The cell assemblies including a micro-heater and thermal and electrical insulating layers. Previously, there are multiple designs of resistive heaters for different types of DACs or experimental configurations7,17,18,19,20. Most of the heaters are machined by individual investigators or purchased from industry which are typically designed for other purposes. Fabricating micro-heaters in a normal machine shop can be time consuming and not always reproducible. In most occasions,&#160;the micro-heaters of different designs from individual groups are not optimized and thoroughly tested. The heaters supplied from industry typically are not designed and optimized for EHDAC experiments. Custom designed and machined heaters are mostly pricy due to the requirement of bulk order by industrial machine shops. Therefore, the infrastructure development of heaters for EHDAC experimentation would benefit the entire community with standardized and thoroughly tested heater assemblies, and well documented preparation procedures. In addition, the design and standardization of thermal and electrical insulating layers can help improve the success rate and temperature stability of the EHDAC experiments. The new EHDAC setup allows routine high-temperature DAC experiments for the broad high-pressure community13.
We have also designed other variations of heaters. The thickness of the heater can be increased to 4.65 mm for the BX90 EHDAC, when backing plates (or seats) with stepped thickness are used. We also designed heaters with varying thickness along the radial direction. They are thinner at the center and thicker near the rim, thus can be used in the EHDAC with short diamonds anvils of Boehler-Almax (BA) design. The DAC with BA diamonds has large opening angles, which is optimal for high-pressure single-crystal XRD experiments.
There are some pros and cons of this technique. The highest achievable temperature is typically limited to 900 K in the open air due to the oxidation and graphitization of diamonds compared with laser-heated DAC. However, higher temperatures above 1200 K have been achieved for a BX90 EHDAC housed in a newly designed and fabricated water-cooled enclosure with protective atmosphere/vacuum and membrane for pressurization. The thermal gradient in the sample chamber of the EHDAC is smaller and the temperature can be stable for a long time (several hours to days) with an easy feed-back control between power and temperature. In this work, the temperature was stable at 500&#176;&#177;2 K for about one day for each Brillouin scattering data collection and multiple heating-cooling cycles can be achieved. Another challenge for the EHDAC is that the pressure sometimes would increase significantly upon heating especially at low pressures (&#60;20 GPa). This could be mitigated by untightening the screws for pressurization before heating or tuning the membrane gas pressure during heating when a membrane pressurization system is used.
There are several critical steps for the EHDAC experimentation. Regarding the placement of the thermocouple for accurate temperature measurements, the thermocouple should be first electrically insulated from the metallic seats and body of the DAC. The junction of the thermocouple should be secured to touch the surface of the diamond&#8217;s pavilion and &#60;1 mm away from the culet, in order to determine the temperature of the sample. Regarding heater preparation, ensuring good thermal insulation surrounding the micro-heater is critical, and it is necessary to wind more spare wires around the wires extending from the heater to reduce the electrical resistivity and thus the temperature of the extension wires during heating.
Here we showcased the utilization of the EHDAC to synthesize single-crystal ice-VII of good quality from liquid H2O at HPHT. Combined with the accurately determined single-crystal orientation by single crystal XRD, the elastic moduli with small uncertainties were determined from Brillouin scattering measurements. The elastic moduli at 300 K of ice-VII were close to the previous data21,22 and the elastic moduli at 500 K was the first HPHT Brillouin results of single-crystal ice-VII reported. The sound velocities and elastic moduli decrease as a function of temperature at 11.2 GPa (Figure 6). Experiments at different pressures and temperatures should be performed to understand the temperature effect on the elastic moduli of ice-VII at elevated pressures. In this case, the EHDAC can be used to synthesize high-pressure phases with low melting temperature, and can also be used to simulate the HPHT conditions in the Earth&#8217;s and planetary interiors. Combined with various detection methods, such as synchrotron XRD and Brillouin spectroscopy, physical properties of planetary materials in deep interiors of planets or moons can be obtained and compared with the geophysical models.

The diamond anvil cell (DAC) is one of the most important tools for high pressure research. Coupled with synchrotron-based and conventional analytical methods, it has been widely used to study properties of planetary materials up to multi-megabar pressures and at wide ranges of temperatures. Most planetary interiors are under both high-pressure and high-temperature (HPHT) conditions. It is thus essential to heat the compressed samples in a DAC at high pressures in situ to study the physics and chemistry of planetary interiors. High temperatures are not only required for the investigations of phase and melting relationships and thermodynamic properties of planetary materials, but also help mitigate pressure gradient, promote phase transitions and chemical reactions, and expedite diffusion and recrystallization. Two methods are typically utilized to heat the samples in DACs: laser-heating and internal/external resistive heating methods.
The laser-heated DAC technique has been employed for high-pressure materials science and mineral physics research of planetary interiors1,2. Although increasing number of laboratories have access to the technique, it usually requires significant development and maintenance effort. The laser heating technique has been used to achieve temperatures as high as 7000 K3. However, long-duration stable heating as well as temperature measurement in laser-heating experiments have been a persistent issue. The temperature during laser heating usually fluctuates but can be mitigated by feed-back coupling between thermal emission and laser power. More challenging is controlling and determining the temperature for assembly of multiple phases of different laser absorbance. The temperature also has a considerably large gradient and uncertainties (hundreds of K), although recent technical development effort has been used to mitigate this issue4,5,6. Temperature gradients in the heated sample area sometimes may further introduce chemical heterogeneities caused by diffusion, re-partitioning or partial melting. In addition, temperatures less than 1100 K typically could not be measured precisely without customized detectors with high sensitivity in the infrared wavelength range.
The EHDAC uses resistive wires or foils around the gasket/seat to heat the entire sample chamber, which provides the ability of heating the sample to ~900 K without a protective atmosphere (such as Ar/H2 gas) and to ~1300 K with a protective atmosphere7. The oxidation and graphitization of diamonds at higher temperatures limit the highest achievable temperatures using this method. Although the temperature range is limited compared with laser-heating, it provides more stable heating for a long duration and a smaller temperature gradient8, and is well suited to be coupled with various detection and diagnostic methods, including optical microscope, X-ray diffraction (XRD), Raman spectroscopy, Brillouin spectroscopy and Fourier-transform infrared spectroscopy9. Therefore, the EHDAC has become a useful tool to study various material properties at HPHT conditions, such as phase stability and transitions10,11, melting curves12, thermal equation of state13, and elasticity14.
The BX-90 type DAC is a newly developed piston-cylinder type DAC with large aperture (90&#176; at maximum) for XRD and laser spectroscopy measurements9, with the space and openings to mount a miniature resistive heater. The U-shaped cut on the cylinder side also provides room to release the stress between the piston and the cylinder side caused by temperature gradient. Therefore, it has recently been widely used in powder or single-crystal XRD and Brillouin measurements with the external-heating setup. In this study, we describe a reproducible and standardized protocol for preparing EHDACs and demonstrated single-crystal XRD as well as Brillouin spectroscopy measurements of synthesized single-crystal ice-VII using the EHDAC at 11.2 GPa and 300-500 K.

<table><tbody><tr><td>Au</td><td>N/A</td><td>N/A</td><td>for pressure calibration</td></tr><tr><td>Deionized water</td><td>Fisher Scientific</td><td>7732-18-5</td><td>for the starting material of ice-VII synthesis</td></tr><tr><td>Diamond anvil cell</td><td>SciStar, Beijing</td><td>N/A</td><td>for generating high pressure</td></tr><tr><td>K-type thermocouple</td><td>Omega</td><td>L-0044K</td><td>for measuring high temperature</td></tr><tr><td>Mica</td><td>Spruce Pine Mica Company</td><td>N/A</td><td>for electrical insulation</td></tr><tr><td>Pt 10wt%Rh</td><td>Alfa Aesar</td><td>10065</td><td>for heater</td></tr><tr><td>Pyrophyllite</td><td>McMaster-Carr</td><td>8479K12</td><td>for fabricating the heater base</td></tr><tr><td>Re</td><td>Sigma-Aldrich</td><td>267317</td><td>for the gasket of diamond anvil cell</td></tr><tr><td>Resbond 919 Ceramic Adhesive</td><td>Cotronics Corp</td><td>Resbond 919-1</td><td>for insulating heating wires and mounting diamonds on seats</td></tr><tr><td>Ruby</td><td>N/A</td><td>N/A</td><td>for pressure calibration</td></tr><tr><td>Ultra-Temp 2300F ceramic tape</td><td>McMaster Carr Supply</td><td>390-23M</td><td>for thermal insulation</td></tr></tbody></table>

an externally-heated diamond anvil cell for synthesis and single-crystal elasticity determination of ice-vii at high pressure-temperature conditions

The externally-heated diamond anvil cell (EHDAC) can be used to generate simultaneously high-pressure and high-temperature conditions found in Earth&#8217;s and planetary interiors. Here we describe the design and fabrication of the EHDAC assemblies and accessories, including ring resistive heaters, thermal and electrical insulating layers, thermocouple placement, as well as the experimental protocol for preparing the EHDAC using these parts. The EHDAC can be routinely used to generate megabar pressures and up to 900 K temperatures in open air, and potentially higher temperatures up to ~1200 K with a protective atmosphere (i.e., Ar mixed with 1% H2). Compared with a laser-heating method for reaching temperatures typically &#62;1100 K, external heating can be easily implemented and provide a more stable temperature at &#8804;900 K and less temperature gradients to the sample. We showcased the application of the EHDAC for synthesis of single crystal ice-VII and studied its single-crystal elastic properties using synchrotron-based X-ray diffraction and Brillouin scattering at simultaneously high-pressure high-temperature conditions.

In this report, we used the fabricated resistive micro-heater and BX-90 DAC for the EHDAC experiment (Figure 1 and Figure 2). Figure 1 shows the machining and fabrication processes of the ring heaters. The standard dimensions of the heater base are 22.30 mm in outer diameter, 8.00&#160;mm in inner diameter and 2.25 mm in thickness. The dimensions of the ring heater can be adjusted to accommodate various types of seats and diamonds.
We heated the compressed H2O sample in an EHDAC at about 6 GPa up to 850 K to synthesize single crystal ice-VII. The ice-VII synthesized from the liquid H2O after several cycles of heating and cooling was a large single crystal (Figure 3). The synthesized single crystal ice VII was utilized for the synchrotron XRD and Brillouin spectroscopy at HPHT. The temperature-power relationship is determined during experiments (Figure 4). The single-crystal XRD data were collected as a set of step scans by rotating the omega angle from -110&#176; to -71&#176; at 0.5&#176;/step. The single crystal ice VII had little lattice stress and retained its good quality after compression and heating, as indicated by the sharp Bragg diffraction peaks in synchrotron-based single crystal XRD images (Figure 5). The diffraction pattern can be indexed with a cubic structure (space group Pnm, Z = 2) with unit cell parameters a = b = c = 3.1375(6) &#197; at 11.2(1) GPa, 300 K and a = b = c = 3.1605(3) &#197; at 11.2(4) GPa, 500 K. The crystallographic orientation of the single-crystal ice-VII are determined to be (-0.105,0.995,0) at 300K and 500 K. The sound velocities and elastic moduli were obtained by high-pressure and high-temperature Brillouin scattering measurements (Figure 6). The obtained elastic moduli are: C11 =89.73(1) GPa, C12 = 55.72(1) GPa and C44 = 56.77(1) GPa, Ks = 67.8(1) GPa and GVRH = 34(6) GPa at 11.2(4) GPa and 300 K; C11 =82.42(1) GPa, C12 = 49.02(1) GPa and C44 = 52.82(1) GPa, Ks = 63(1) GPa and GVRH = 30(5) GPa at 11.2(4) GPa and 500 K.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61389/61389fig01.jpg" /> 
Figure 1: Fabrication of ceramic ring heater base and a micro heater with Pt/Rh wires. 
(A) 3-D model of the heater base (B) Milling the pyrophyllite heater base by the CNC machine. (C) Heater bases sintered in the furnace at 1523 K. (D) Heater with Pt/Rh wires and insulators (mica, insulating tube and high-temp braid sleeving). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61389/61389fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61389/61389fig02.jpg" /> 
Figure 2: Preparation of EHDAC for high-pressure and high-temperature experiments. 
(A) BX-90 DAC with thermocouple installed. (B) Zoom-in view of the placement of thermocouples near the diamond culet. (C, D) The placement of micro-heater in the EHDAC. (E) EHDAC on the cell holder with the heater connected to a DC power supply and thermocouples connected to a thermometer. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61389/61389fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/61389/61389fig03.jpg" /> 
Figure 3: Synthesis of single crystal ice-VII in an EHDAC at about 6 GPa up to 850 K. 
(A) Polycrystalline ice-VII crystallized from the supercooling water at high pressure and high temperature. (B) Growth of polycrystalline ice-VII by decreasing the temperature. (C) Growth of a large single-crystal ice-VII and melting of other smaller crystals after multiple heating and cooling cycles. (D) Growth of one single-crystal ice-VII to fill the sample chamber by further decreasing the temperature. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61389/61389fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/61389/61389fig04.jpg" /> 
Figure 4: The temperature-power relationship of the EHDAC experiments. 
Solid squares represent the temperature-power data in this study, which can be linearly fitted (solid line). This is consistent with the relationship (dashed line) in previous work7. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61389/61389fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/61389/61389fig05.jpg" /> 
Figure 5: Single crystal XRD pattern of ice-VII at 11.2 GPa and 500 K. 
Diffraction peaks of single crystal ice-VII were marked by black boxes. Red labels correspond to Miller indices (hkl) of the diffraction peaks. Other single-crystal peaks are from single-crystal diamond anvils used in the EHDAC. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61389/61389fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/61389/61389fig06.jpg" /> 
Figure 6: Sound velocities of single crystal ice-VII at 11.2(1) GPa, 300 K and 11.2(4) GPa, 500 K. 
(A) Representative Brillouin spectra of ice-VII at &#967; angle = 260 &#176; (B) Sound velocities of ice-VII as a function of rotational &#967; angles. Solid symbols represent the measured velocities by Brillouin spectroscopy. Dashed lines represent the calculated velocities from the best-fit single-crystal elasticity model. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61389/61389fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions at JoVE.c

An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions

This work focuses on the standard protocol for preparing the externally-heated diamond anvil cell (EHDAC) for generating high-pressure and high-temperature (HPHT) conditions. The EHDAC is employed to investigate materials in Earth and planetary interiors under extreme conditions, which can be also used in solid state physics and chemistry studies.

The externally-heated diamond anvil cell (EHDAC) can be used to generate simultaneously high-pressure and high-temperature conditions found in ...

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Nanyang Technological University

Research

JoVE Journal

Chemistry

6.0K Views.  China University of Geosciences (Wuhan). Extern verwarmde diamant aambeeld cel kan gelijktijdig hoge druk en hoge temperatuur te genereren, om de omstandigheden in de onze en andere planeten interieurs te simuleren. Het belangrijkste voordeel van deze techniek is dat het kan worden gecombineerd met verschillende spectroscopische technieken, zoals optische microscopie, röntgendiffractie, Raman spectroscopie en Brillouin verstrooiing. Deze techniek wordt gebruikt om interieurs van rotsachtige planeten en de maan te bestuderen....

Video: An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40&#160;&#176;C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.
The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)1-4. For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus is a unique tool to study, without sampling, phase behavior under a wide range of pressures. Using a cathetometer, very precise volume measurements can be recorded to measure liquid expansion and phase composition. Thus, this synthetic method enables the study of (1) phase equilibria of multi-component mixtures and (2) the partition behavior of catalyst or model compounds as a function of pressure.

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. ...

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

Engineering

Simulation of the Planetary Interior Differentiation Processes in the Laboratory

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to that layered structure, (1) percolation of liquid metal in a solid silicate matrix by planet differentiation, and (2) inner core crystallization by subsequent planet cooling. We conduct high-pressure and high-temperature experiments to simulate both processes in the laboratory. Formation of percolative planetary core depends on the efficiency of melt percolation, which is controlled by the dihedral (wetting) angle. The percolation simulation includes heating the sample at high pressure to a target temperature at which iron-sulfur alloy is molten while the silicate remains solid, and then determining the true dihedral angle to evaluate the style of liquid migration in a crystalline matrix by 3D visualization. The 3D volume rendering is achieved by slicing the recovered sample with a focused ion beam (FIB) and taking SEM image of each slice with a FIB/SEM crossbeam instrument. The second set of experiments is designed to understand the inner core crystallization and element distribution between the liquid outer core and solid inner core by determining the melting temperature and element partitioning at high pressure. The melting experiments are conducted in the multi-anvil apparatus up to 27 GPa and extended to higher pressure in the diamond-anvil cell with laser-heating. We have developed techniques to recover small heated samples by precision FIB milling and obtain high-resolution images of the laser-heated spot that show melting texture at high pressure. By analyzing the chemical compositions of the coexisting liquid and solid phases, we precisely determine the liquidus curve, providing necessary data to understand the inner core crystallization process.

The high-pressure and high-temperature experiments described here mimic planet interior differentiation processes. The processes are visualized and better understood by high-resolution 3D imaging and quantitative chemical analysis.

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to ...

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature (&#62; 300 &#176;C). However, because of the low stress resolution of current solid-pressure-medium apparatuses, high-resolution measurements are today restricted to low-pressure deformation experiments in the gas-pressure-medium apparatus. A new generation of solid-medium piston-cylinder (&#34;Griggs-type&#34;) apparatus is here described. Able to perform high-pressure deformation experiments up to 5 GPa and designed to adapt an internal load cell, such a new apparatus offers the potential to establish a technological basis for high-pressure rheology. This paper provides video-based detailed documentation of the procedure (using the &#34;conventional&#34; solid-salt assembly) to perform high-pressure, high-temperature experiments with the newly designed Griggs-type apparatus. A representative result of a Carrara marble sample deformed at 700 &#176;C, 1.5 GPa and 10-5 s-1 with the new press is also given. The related stress-time curve illustrates all steps of a Griggs-type experiment, from increasing pressure and temperature to sample quenching when deformation is stopped. Together with future developments, the critical steps and limitations of the Griggs apparatus are then discussed.

Rock deformation needs to be quantified at high pressure. A description of the procedure to perform deformation experiments in a newly designed solid-medium Griggs-type apparatus is here given. This provides technological basis for future rheological studies at pressures up to 5 GPa.

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature ...

Environment

Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) coupled with synchrotron X-radiation. A cube-shaped sample assembly is prepared and compressed, at room temperature, by a set of four X-ray transparent sintered diamond anvils and two tungsten carbide anvils, in the lateral and the vertical planes, respectively. All six anvils are housed within a 250-ton hydraulic press and driven inward simultaneously by two wedged guide blocks. A horizontal energy dispersive X-ray beam is projected through and diffracted by the sample assembly. The beam is commonly in the mode of either white or monochromatic X-ray. In the case of white X-ray, the diffracted X-rays are detected by a solid-state detector array that collects the resulting energy dispersive diffraction pattern. In the case of monochromatic X-ray, the diffracted pattern is recorded using a two-dimensional (2-D) detector, such as an imaging plate or a charge-coupled device (CCD) detector. The 2-D diffraction patterns are analyzed to derive lattice spacings. The elastic strains of the sample are derived from the atomic lattice spacing within grains. The stress is then calculated using the predetermined elastic modulus and the elastic strain. Furthermore, the stress distribution in two-dimensions allow for understanding how stress is distributed in different orientations. In addition, a scintillator in the X-ray path yields a visible light image of the sample environment, which allows for the precise measurement of sample length changes during the experiment, yielding a direct measurement of volume strain on the sample. This type of experiment can quantify the stress distribution within geomaterials, which can ultimately shed light on the mechanism responsible for compaction. Such knowledge has the potential to significantly improve our understanding of key processes in rock mechanics, geotechnical engineering, mineral physics, and material science applications where compactive processes are important.

We report detailed procedures for compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus coupled with synchrotron X-radiation. Such experiments allow quantification of the stress distribution within samples, that ultimately sheds light on compaction processes in geomaterials.

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) ...

High Pressure Single Crystal Diffraction at PX^2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe2+0.14Fe3+0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 &#177;0.006 &#197;, b = 8.761 &#177;0.004 &#197;, c = 5.248 &#177;0.001 &#197;, &#946; = 105.06 &#177;0.03&#186;, &#945; = &#947; = 90&#186;.

In this report, we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell at the GSECARS 13-BM-C beamline at the Advanced Photon Source. ATREX and RSV programs are used to analyze the data.

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the ...

Determining the Mechanical Strength of Ultra-Fine-Grained Metals

The mechanical strengthening of metals is the long-standing challenge and popular topic of materials science in industries and academia. The size dependence of the strength of the nanometals has been attracting a lot of interest. However, characterizing the strength of materials at the lower nanometer scale has been a big challenge because the traditional techniques become no longer effective and reliable, such as nano-indentation, micropillar compression, tensile, etc. The current protocol employs radial diamond-anvil cell (rDAC) X-ray diffraction (XRD) techniques to track differential stress changes and determine the strength of ultrafine metals. It is found that ultrafine nickel particles have more significant yield strength than coarser particles, and the size strengthening of nickel continues down to 3 nm. This vital finding immensely depends on effective and reliable characterizing techniques. The rDAC XRD method is expected to play a significant role in studying and exploring nanomaterial mechanics.

The protocol presented here describes the high-pressure radial diamond-anvil-cell experiments and analyzing the related data, which are essential for obtaining the mechanical strength of the nanomaterials with a significant breakthrough to the traditional approach.

The mechanical strengthening of metals is the long-standing challenge and popular topic of materials science in industries and academia. The size ...

Automated Protein Crystallization and Real-Time Data Collection

Crystallization and In Situ Room Temperature Data Collection Using the Crystallization Facility at Harwell and Beamline VMXi, Diamond Light Source

Protocols for robotic protein crystallization using the Crystallization Facility at Harwell and in situ room temperature data collection from crystallization plates at Diamond Light Source beamline VMXi are described. This approach enables high-quality room-temperature crystal structures to be determined from multiple crystals in a straightforward manner and provides very rapid feedback on the results of crystallization trials as well as enabling serial crystallography. The value of room temperature structures in understanding protein structure, ligand binding, and dynamics is becoming increasingly recognized in the structural biology community. This pipeline is accessible to users from all over the world with several available modes of access. Crystallization experiments that are set up can be imaged and viewed remotely with crystals identified automatically using a machine learning tool. Data are measured in a queue-based system with up to 60&#176; rotation datasets from user-selected crystals in a plate. Data from all the crystals within a particular well or sample group are automatically merged using xia2.multiplex with the outputs straightforwardly accessed via a web browser interface.

Author Spotlight: Advancing Protein Structure Analysis for Drug Development 

We present a protocol for the crystallization of proteins using the crystallization facility in the Research Complex at Harwell and subsequent in situ X-ray crystallographic data collection from crystals within the plates at Diamond&#39;s Versatile Macromolecular Crystallography in situ (VMXi) beamline. We describe sample requirements, crystallization protocols, and data collection guidelines.

An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions

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