Diamond Anvil Cell System Research Articles

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

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

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.

Measurement of the temperature distribution on the surface of the laser heated specimen in a diamond anvil cell system by the tandem imaging acousto-optical filter

ABSTRACTWe demonstrate that combining the laser heating (LH) system in a diamond anvil cell (DAC) with a tandem acousto-optical tunable filter (TAOTF) allows measurement of the temperature distribution (TD) under infrared (IR, 1064 nm) LH of a specimen under high pressure in a DAC. The main component of the system is a TAOTF synchronized with a video camera. The system allows TD mapping within a temperature range of approximately 1000–2000 K on the surface of a laser-heated object (Fe plates) at high pressure in a DAC with a spatial resolution 2 µm by fitting the actual signal to Planck’s equation at each point.

Combined laser ultrasonics, and Raman scattering in diamond anvil cell system operating in the transmission configuration

Recently it has been demonstrated that it is possible to detect both longitudinal and shear waves as well as measure their velocities for a non-transparent iron layer compressed in a diamond anvil cell (DAC) to pressures approaching 23 GPa by using laser ultrasonics (LU) technique. These experiments were conducted in the reflection configuration when point source and point receiver were located at the same side of the specimen. The purpose of the present study is to examine the generation and detection of the acoustical waves in the LU-DAC system operating in the transmission configuration. The experimental results obtained at 16.4 GPa presented in this article demonstrate that the LU-DAC technique can be applied for longitudinal wave velocity measurements in small specimens under high pressure in the transmission configuration.

Combined laser ultrasonics, laser heating, and Raman scattering in diamond anvil cell system.

We developed a multi-functional in situ measurement system under high pressure equipped with a laser ultrasonics (LU) system, Raman device, and laser heating system (LU-LH) in a diamond anvil cell (DAC). The system consists of four components: (1) a LU-DAC system (probe and pump lasers, photodetector, and oscilloscope) and DAC; (2) a fiber laser, which is designed to allow precise control of the total power in the range from 2 to 100 W by changing the diode current, for heating samples; (3) a spectrometer for measuring the temperature of the sample (using black body radiation), fluorescence spectrum (spectrum of the ruby for pressure measurement), and Raman scattering measurements inside a DAC under high pressure and high temperature (HPHT) conditions; and (4) an optical system to focus laser beams on the sample and image it in the DAC. The system is unique and allows us to do the following: (a) measure the shear and longitudinal velocities of non-transparent materials under HPHT; (b) measure temperature in a DAC under HPHT conditions using Planck's law; (c) measure pressure in a DAC using a Raman signal; and (d) measure acoustical properties of small flat specimens removed from the DAC after HPHT treatment. In this report, we demonstrate that the LU-LH-DAC system allows measurements of velocities of the skimming waves in iron at 2580 K and 22 GPa.

A Peltier cooling diamond anvil cell for low-temperature Raman spectroscopic measurements.

A new cooling system using Peltier modules is presented for a low-temperature diamond anvil cell instrument. This cooling system has many advantages: it is vibration-free, low-cost, and compact. It consists of double-stacked Peltier modules and heat sinks, where a cooled ethylene glycol-water mixture flows through a chiller. Current is applied to the Peltier modules by two programmable DC power supplies. Sample temperature can be controlled within the range 210-300 K with a precision of ±0.1 K via a Proportional-Integral-Differential (PID) control loop. A Raman spectroscopic study for the H2O ice VII-VIII transition is shown as an example of an application of the Peltier cooling diamond anvil cell system.

Simulation of laser-generated longitudinal and shear ultrasonic waves in a diamond anvil cell by the finite element method

Based on the thermoelastic theory, a numerical model of ultrasonic displacement field induced by a vertical incident pulsed laser in an aluminum film in a diamond anvil cell (DAC) is established by using the finite element method (FEM). After precisely calculating the transient temperature field distributions, the bulk ultrasonic waveforms on the rear surface of the film and the characteristics of ultrasonic displacement field with time are obtained. Then directivity patterns of laser-generated longitudinal and shear ultrasonic waves are analyzed in details. The numerical results indicate that the thermoelastic force source and the characteristics of ultrasonic directivity are strongly affected by the diamond window. The energy of longitudinal wave is concentrated near the laser incident direction, and the one of shear wave is concentrated between 30° and 60° that deflected from the laser incident direction to the excited source. These characteristics in DAC system are different from the results of free surface in thermoelastic effect, while are similar to the results of free surface in ablation effect.

Construction of laser-heated diamond anvil cell system for in situ x-ray diffraction study at SPring-8

A double-sided laser heated diamond anvil cell (DAC) system was constructed at a high brilliance, undulator beamline (BL10XU) at SPring-8 a third generation synchrotron radiation facility, for performing in situ angle-dispersive x-ray diffraction experiments under high temperature and high pressure. The design of this system puts emphasis on reliable data collection for the structural analysis. With this system, the adjustment of the optical systems for both x-ray and laser beams can be done easily, and high quality diffraction data can be obtained typically within several minutes. A system for temperature measurement of ten points in a sample area at the same time was also developed. The performance of the laser heated DAC system was tested by observing phase transitions of natural olivine.

Laser-heated diamond anvil cell system for photochemical reaction measurements

A laser heating system constructed for photochemical reaction within a diamond anvil cell features a tunable pulsed laser and an excimer laser ranging from ultraviolet to infrared in a continuous-wave Nd:yttrium–aluminum–garnet laser heating system. Pulse duration is measured during experiments using a high-speed photoreceiver and pulse modes are measured by a beam profiler. High-purity synthetic diamond with high ultraviolet transmittance are used to avoid damaging the anvils. Decomposition of silver iodide by an excimer laser irradiation is confirmed under high pressure. This laser technology will, combined with high-pressure experiments, open up avenues in photochemical reaction processes.

Laser heated diamond cell system at the Advanced Photon Source for in situ x-ray measurements at high pressure and temperature

We describe a laser heated diamond anvil cell system at the GeoSoilEnviroCARS sector at the Advanced Photon Source. The system can be used for in situ x-ray measurements at simultaneously ultrahigh pressures (to >150 GPa) and ultrahigh temperatures (to >4000 K). Design goals of the laser heating system include generation of a large heating volume compared to the x-ray beam size, minimization of the sample temperature gradients both radially and axially in the diamond anvil cell, and maximization of heating stability. The system is based on double-sided laser heating technique and consists of two Nd:YLF lasers with one operating in TEM00 mode and the other in TEM01* mode, optics to heat the sample from both sides, and two spectroradiometric systems for temperature measurements on both sides. When combined with an x-ray microbeam (3–10 μm) technique, a temperature variation of less than 50 K can be achieved within an x-ray sampled region for longer than 10 min. The system has been used to obtain in situ structural data and high temperature equations of state on metals, oxides, and silicates to 3500 K and 160 GPa.

ＤＡＣ技術入門 ＩＩ ＤＡＣの半導体の光学測定への応用

In this article, a diamond anvil cell system for optical studies at variable pressure and at low temperatures is described. A remotely controlled pneumatic driver unit, which consists of a pair of coaxial bellows, operates with helium gas. The setup and techniques for photoreflectance (PR) and time-resolved photoluminescence (TRPL) measurements with a diamond anvil cell are presented. Examples of the application to PR and TRPL in III-V semiconductor alloys under high pressure are shown.