Artykuły w czasopismach: „High-pressure Techniques - Diamond Anvil Cell (DAC)”

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Li, Bing, Cheng Ji, Wenge Yang, Junyue Wang, Ke Yang, Ruqing Xu, Wenjun Liu, Zhonghou Cai, Jiuhua Chen i Ho-kwang Mao. "Diamond anvil cell behavior up to 4 Mbar". Proceedings of the National Academy of Sciences 115, nr 8 (5.02.2018): 1713–17. http://dx.doi.org/10.1073/pnas.1721425115.

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The diamond anvil cell (DAC) is considered one of the dominant devices to generate ultrahigh static pressure. The development of the DAC technique has enabled researchers to explore rich high-pressure science in the multimegabar pressure range. Here, we investigated the behavior of the DAC up to 400 GPa, which is the accepted pressure limit of a conventional DAC. By using a submicrometer synchrotron X-ray beam, double cuppings of the beveled diamond anvils were observed experimentally. Details of pressure loading, distribution, gasket-thickness variation, and diamond anvil deformation were studied to understand the generation of ultrahigh pressures, which may improve the conventional DAC techniques.

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Okuda, Yoshiyuki, Kenta Oka, Koutaro Hikosaka i Kei Hirose. "Novel non-Joule heating technique: Externally laser-heated diamond anvil cell". Review of Scientific Instruments 94, nr 4 (1.04.2023): 043901. http://dx.doi.org/10.1063/5.0122111.

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The externally heated diamond anvil cell (EHDAC) conducts high pressure and temperature experiments with spatial uniformity and temporal stability. These are conventionally combined with various spectroscopies and x-ray diffraction measurements. EHDAC techniques perform Joule heating on a heater placed close to or directly in contact with diamond anvils. However, the electrical wiring and heater required for Joule heating complicate EHDAC setups, hindering easy access for the measurement of physical properties. This study proposes an EHDAC technique using laser- instead of Joule-heating. We successfully achieved temperatures reaching 900 K by applying heat to diamond anvils through laser-heating of the gaskets with thermally insulating anvil seats. To test this setup, we measured the melting temperature of H2O ice VII, which was consistent with previous studies. We also measured the high-pressure and temperature impedance of H2O VII and verified the capability of electrical resistivity measurements in this setup. This technique allows various physical property measurements owing to its simple setup required for externally laser-heated diamond anvil cell experiments. The unique characteristics of this heating technique are that (1) no heaters or wiring are required, (2) it exhibits the most efficient heating among EHDAC studies, (3) it maintains the DAC body at room temperature, and (4) diamond anvils do not detach from anvil seats after the EHDAC experiment. This method significantly simplifies the experimental setup, which allows much easier access to various physical property measurements using an EHDAC.

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Amaya, K., K. Shimizu i M. I. Eremets. "Search for Superconductivity under Ultra-high Pressure". International Journal of Modern Physics B 13, nr 29n31 (20.12.1999): 3623–25. http://dx.doi.org/10.1142/s0217979299003568.

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Techniques of producing ultra-high pressure at very low temperature and measuring method of electrical resistance and magnetization of samples confirmed in the used diamond anvil ceil (DAC) are shortly described. Experimental results on simple molecular systems such as iodine, sulfur, oxygen and organic iodanil are reviewed as typical example of pressure induced superconductivity.

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Katrusiak, Andrzej. "Lab in a DAC – high-pressure crystal chemistry in a diamond-anvil cell". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, nr 6 (15.11.2019): 918–26. http://dx.doi.org/10.1107/s2052520619013246.

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The diamond-anvil cell (DAC) was invented 60 years ago, ushering in a new era for material sciences, extending research into the dimension of pressure. Most structural determinations and chemical research have been conducted at ambient pressure, i.e. the atmospheric pressure on Earth. However, modern experimental techniques are capable of generating pressure and temperature higher than those at the centre of Earth. Such extreme conditions can be used for obtaining unprecedented chemical compounds, but, most importantly, all fundamental phenomena can be viewed and understood from a broader perspective. This knowledge, in turn, is necessary for designing new generations of materials and applications, for example in the pharmaceutical industry or for obtaining super-hard materials. The high-pressure chambers in the DAC are already used for a considerable variety of experiments, such as chemical reactions, crystallizations, measurements of electric, dielectric and magnetic properties, transformations of biological materials as well as experiments on living tissue. Undoubtedly, more applications involving elevated pressure will follow. High-pressure methods become increasingly attractive, because they can reduce the sample volume and compress the intermolecular contacts to values unattainable by other methods, many times stronger than at low temperature. The compressed materials reveal new information about intermolecular interactions and new phases of single- and multi-component compounds can be obtained. At the same time, high-pressure techniques, and particularly those of X-ray diffraction using the DAC, have been considerably improved and many innovative developments implemented. Increasingly more equipment of in-house laboratories, as well as the instrumentation of beamlines at synchrotrons and thermal neutron sources are dedicated to high-pressure research.

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Dasenbrock-Gammon, Nathan, Raymond McBride, Gyeongjae Yoo, Sachith Dissanayake i Ranga Dias. "Second harmonic AC calorimetry technique within a diamond anvil cell". Review of Scientific Instruments 93, nr 9 (1.09.2022): 093901. http://dx.doi.org/10.1063/5.0104705.

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Tuning the energy density of matter at high pressures gives rise to exotic and often unprecedented properties, e.g., structural transitions, insulator–metal transitions, valence fluctuations, topological order, and the emergence of superconductivity. The study of specific heat has long been used to characterize these kinds of transitions, but their application to the diamond anvil cell (DAC) environment has proved challenging. Limited work has been done on the measurement of specific heat within DACs, in part due to the difficult experimental setup. To this end, we have developed a novel method for the measurement of specific heat within a DAC that is independent of the DAC design and is, therefore, readily compatible with any DACs already performing high pressure resistance measurements. As a proof-of-concept, specific heat measurements of the MgB2 superconductor were performed, showing a clear anomaly at the transition temperature ( T c), indicative of bulk superconductivity. This technique allows for specific heat measurements at higher pressures than previously possible.

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SHIMIZU, KATSUYA. "PRESSURE-INDUCED SUPERCONDUCTIVITY IN SYMPLE METALS". International Journal of Modern Physics B 19, nr 01n03 (30.01.2005): 259–61. http://dx.doi.org/10.1142/s0217979205028360.

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Experimental results in search for pressure-induced superconductivity are reviewed. Typical examples are simple inorganic and organic molecular crystals, magnetic metals, and elements. We have developed complex extreme condition of very low temperature down to 30 mK and ultra high pressure exceeding 200 GPa by assembling compact diamond-anvil cell (DAC) on a powerful 3 He /4 He dilution refrigerator. Using the newly developed apparatus and techniques, we have studied superconductivity in various materials in various pressure range. In this paper, we will shortly review our newly developed experimental apparatus and techniques and discuss about examples of pressure-induced superconductivity in simple metals.

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Hofmeister, A. M. "Infrared Microspectroscopy in Earth and Planetary Science: Recent Developments, Including In Situ High-Pressure, High-Temperature Techniques". Microscopy and Microanalysis 3, S2 (sierpień 1997): 857–58. http://dx.doi.org/10.1017/s143192760001117x.

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Vibrational spectroscopy is used in Earth science for both quantitative and qualitative analysis. This report focuses on infrared (IR) spectroscopy, although similar efforts are on-going in Raman spectroscopy.Qualitative studies utilize the fact that the vibrational spectrum is a characteristic of a material: hence comparison to a set of standards allows for identification of the phase. Most of these types of studies in Earth science involve macrosamples, but measurements of microsamples from meteorites are on interest in order to identify the structure of SiC inclusions and the type of organic compounds in interplanetary dust. As most of these samples are micron sized, which is below the diffraction limit for the mid-IR, the approach has been to compress the sample using a diamond anvil cell (DAC) into a disk of sub-micron thickness, adhere the sample to a KBr plate, and to subsequently remove the disk from the DAC and obtain spectra with the aid of an FTIR microscope.

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Kudoh, Yasuhiro. "Introduction to DAC Techniques. Single Crystal X-ray Diffraction Technique at High Pressure Using Diamond Anvil Cell." REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY 8, nr 1 (1998): 10–16. http://dx.doi.org/10.4131/jshpreview.8.10.

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Hirose, Kei. "Deep Earth mineralogy revealed by ultrahigh-pressure experiments". Mineralogical Magazine 78, nr 2 (kwiecień 2014): 437–46. http://dx.doi.org/10.1180/minmag.2014.078.2.13.

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AbstractUltrahigh-pressure and -temperature (P-T) experimental techniques have progressed rapidly in recent years. By combining them with X-ray diffraction measurements at synchrotron radiation facilities, it is now possible to examine deep Earth mineralogy in situ at relevant high P-T conditions in a laser-heated diamond anvil cell (DAC). The lowermost part of the mantle, known as the D″ layer, has long been enigmatic because of a number of unexplained seismological features. Nevertheless, the discovery of a phase transition from MgSiO3 perovskite to ‘post-perovskite’ above 120 GPa and 2400 K indicates that post-perovskite is a principal constituent in the lowermost mantle, which is compatible with seismic observations. The ultrahigh P-T conditions of the Earth’s core have not been accessible by static experiments, but the structure and phase transition of Fe and Fe-alloys are now being examined up to 400 GPa and 6000 K by laser-heated DAC studies.

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Gavryushkin, Pavel N., Altyna Bekhtenova, Sergey S. Lobanov, Anton Shatskiy, Anna Yu Likhacheva, Dinara Sagatova, Nursultan Sagatov i in. "High-Pressure Phase Diagrams of Na2CO3 and K2CO3". Minerals 9, nr 10 (30.09.2019): 599. http://dx.doi.org/10.3390/min9100599.

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The phase diagrams of Na 2 CO 3 and K 2 CO 3 have been determined with multianvil (MA) and diamond anvil cell (DAC) techniques. In MA experiments with heating, γ -Na 2 CO 3 is stable up to 12 GPa and above this pressure transforms to P 6 3 /mcm-phase. At 26 GPa, Na 2 CO 3 - P 6 3 /mcm transforms to the new phase with a diffraction pattern similar to that of the theoretically predicted Na 2 CO 3 - P 2 1 /m. On cold compression in DAC experiments, γ -Na 2 CO 3 is stable up to the maximum pressure reached of 25 GPa. K 2 CO 3 shows a more complex sequence of phase transitions. Unlike γ Na 2 CO 3 , γ -K 2 CO 3 has a narrow stability field. At 3 GPa, K 2 CO 3 presents in the form of the new phase, called K 2 CO 3 -III, which transforms into another new phase, K 2 CO 3 -IV, above 9 GPa. In the pressure range of 9–15 GPa, another new phase or the mixture of phases III and IV is observed. The diffraction pattern of K 2 CO 3 -IV has similarities with that of the theoretically predicted K 2 CO 3 - P 2 1 /m and most of the diffraction peaks can be indexed with this structure. Water has a dramatic effect on the phase transitions of K 2 CO 3 . Reconstruction of the diffraction pattern of γ -K 2 CO 3 is observed at pressures of 0.5–3.1 GPa if the DAC is loaded on the air.

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Jiang, Runze, Chunyuan Lan, Jinxue Du i Renbiao Tao. "Realization of parallel experiments in a diamond anvil cell and their application to water–mineral interactions at high-pressure and high-temperature conditions". Review of Scientific Instruments 93, nr 5 (1.05.2022): 053905. http://dx.doi.org/10.1063/5.0075021.

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Parallel experiments are normally used to compare different chemical systems and conditions simultaneously. In the field of high-pressure experimental science, parallel experiments are hard to realize due to very limited reaction chamber size for the generation of high-pressure conditions, especially in diamond anvil cells (DACs). Multiple holes, instead of a single hole, can be drilled into a gasket (i.e., multihole gasket technique) to realize parallel experiments in a DAC. In this study, we conducted a series of systematic calibration experiments on multihole gasket techniques using statistical methods. Multiple (two or three or four) holes 100 µm in diameter were symmetrically drilled into a gasket by a laser drilling instrument with the help of a coded Python program. The pressure deviations among different holes in a gasket at average pressures below 10 GPa are constrained to less than 0.2 GPa in all calibration experiments at room temperature. We further checked the influences of the gasket material, hole number, pre-indented gasket thickness, and temperature on the pressure deviations among different holes in a gasket. Finally, we applied the multihole gasket technique in a DAC experiment and compared the solubility of calcite in different chemical environments at the same pressure and temperature conditions. The experimental results showed that the multihole gasket technique could be widely applied to study water–mineral interactions at high-P (<10 GPa) and high-T (<700 °C) conditions because multiple parallel experiments can be efficiently realized simultaneously.

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Yusa, Hitoshi. "Introduction to DAC Techniques. Technology for Generating High-Temperature in Diamond Anvil Cell by Using Lasers." REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY 8, nr 1 (1998): 49–56. http://dx.doi.org/10.4131/jshpreview.8.49.

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Xu, Jianing, Lingkong Zhang, Hailun Wang, Yan Gao, Tingcha Wei, Resta A. Susilo, Congwen Zha, Bin Chen, Hongliang Dong i Zhiqiang Chen. "Phase Transitions in Amorphous Germanium under Non-Hydrostatic Compression". Crystals 12, nr 7 (24.06.2022): 898. http://dx.doi.org/10.3390/cryst12070898.

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As the pioneer semiconductor in transistor, germanium (Ge) has been widely applied in information technology for over half a century. Although many phase transitions in Ge have been reported, the complicated phenomena of the phase structures in amorphous Ge under extreme conditions are still not fully investigated. Here, we report the different routes of phase transition in amorphous Ge under different compression conditions utilizing diamond anvil cell (DAC) combined with synchrotron-based X-ray diffraction (XRD) and Raman spectroscopy techniques. Upon non-hydrostatic compression of amorphous Ge, we observed that shear stress facilitates a reversible pressure-induced phase transformation, in contrast to the pressure-quenchable structure under a hydrostatic compression. These findings afford better understanding of the structural behaviors of Ge under extreme conditions, which contributes to more potential applications in the semiconductor field.

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Lin, Chia-Min, Kaleb Burrage, Chris Perreault, Wei-Chih Chen, Cheng-Chien Chen i Yogesh K. Vohra. "Theoretical and experimental studies of compression and shear deformation behavior of Osmium to 280 GPa". Engineering Research Express 3, nr 4 (11.11.2021): 045017. http://dx.doi.org/10.1088/2631-8695/ac34c4.

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Abstract The compression behavior of osmium metal was investigated up to 280 GPa (volume compression V/Vo = 0.725) under nonhydrostatic conditions at ambient temperature using angle dispersive axial x-ray diffraction (A-XRD) with a diamond anvil cell (DAC). In addition, shear strength of osmium was measured to 170 GPa using radial x-ray diffraction (R-XRD) technique in DAC. Both diffraction techniques in DAC employed platinum as an internal pressure standard. Density functional theory (DFT) calculations were also performed, and the computed lattice parameters and volumes under compression are in good agreement with the experiments. DFT predicts a monotonous increase in axial ratio (c/a) with pressure and the structural anomalies of less than 1% in (c/a) ratio reported below 150 GPa were not reproduced in theoretical calculations and hydrostatic measurements. The measured value of shear strength of osmium ( τ ) approaches a limiting value of 6 GPa above a pressure of 50 GPa in contrast to theoretical predictions of 24 GPa and is likely due to imperfections in polycrystalline samples. DFT calculations also enable the studies of shear and tensile deformations. The theoretical ideal shear stress is found along the (001)[1–10] shear direction with the maximal shear stress ∼24 GPa at critical strain ∼0.13.

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Alabdulkarim, Mohamad E., Wendy D. Maxwell, Vibhor Thapliyal i James L. Maxwell. "A Comprehensive Review of High-Pressure Laser-Induced Materials Processing, Part I: Laser-Heated Diamond Anvil Cells". Journal of Manufacturing and Materials Processing 6, nr 5 (29.09.2022): 111. http://dx.doi.org/10.3390/jmmp6050111.

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Laser-heated diamond anvil cell (LH-DAC) experimentation has emerged as a leading technique for materials processing at extreme pressures and temperatures. LH-DAC systems are often employed to better characterise the structure and properties of materials in applications ranging from condensed matter physics to geophysical research to planetary science. This article reviews LH-DAC and related laser-based characterisation, as the first part of a series within the broader context of all high-pressure laser-induced material processing. In part I of this review, a synopsis of laser-heated diamond anvil cell experimental methods, developmental history, fundamental physicochemical processes, and emerging research trends are provided. Important examples of minerals/materials modified during LH-DAC investigations (since their inception) are also tabulated, including key phase transformations, material syntheses, laser parameters, and process conditions—as a reference for the reader and as a guide for directing future research efforts. Note that laser-dynamic-compression within diamond anvil cells (LDC-DAC experimentation) and laser-induced reactive chemical synthesis within diamond anvil cells (LRS-DAC experimentation) are treated separately, as Parts II and III of this review.

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Sun, Yong Zhou, Jiu Hua Chen, Vadym Drozd i Shah Najiba. "Behavior of Decomposed Ammonia Borane at High Pressure up to ~10 GPa". Materials Science Forum 783-786 (maj 2014): 1829–35. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1829.

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We conductedin situRaman spectroscopy study on ammonia borane loaded in diamond anvil cell (DAC). The ammonia borane was decomposed at around 140 degree Celsius under the pressure ~0.7 GPa. Raman spectra show the hydrogen was desorbed within 1 hour at 140 degree Celsius. The hydrogen was sealed in the DAC well and cooled down near to room temperature. Applying higher pressure up to ~10 GPa indicates interactions between the products and loss of dihydrogen bonding. No rehydrogenation was detected in the pressure range investigated.Keywords: Ammonia borane; Diamond anvil cell; High pressure; Phase transition

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Jiang, Dawei, Min Cao, Xiaotong Zhang, Yang Gao i Yonghao Han. "Pressure evolution in a diamond anvil cell without a pressure medium". Journal of Applied Physics 131, nr 12 (28.03.2022): 125904. http://dx.doi.org/10.1063/5.0086792.

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The inhomogeneity in pressure inside the sample chamber of a diamond anvil cell (DAC) poses a major challenge to the accurate measurement of the properties of materials under high pressures, especially when the pressure medium solidifies under compression or is prohibited in the experiment. In this paper, the authors systematically investigate the pressure gradient in a DAC sample chamber and its evolution over time with changes in temperature. The results show that pressure gradients were formed along both the radial and the axial directions upon compression, and gradually decayed with time and increasing temperature. After a period of relaxation at room temperature, the pressure gradient along the axial direction gradually decayed and a new equilibrium was established. A similar process was observed along the radial direction but required a longer period before reaching equilibrium. Appropriate heating of the sample can cut the relaxation time to the order of tens of minutes and smoothen the pressure gradient in both directions. The electrical properties of olivine were significantly different when the measurements were conducted before and after relaxation was complete, indicating that the relaxation in pressure is essential for acquiring reliable data in a DAC under high pressures.

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Sorokin, Boris P., Nikita O. Asafiev, Danila A. Ovsyannikov, Gennady M. Kvashnin, Mikhail Yu Popov, Nikolay V. Luparev, Anton V. Golovanov i Vladimir D. Blank. "Microwave acoustic studies of materials in diamond anvil cell under high pressure". Applied Physics Letters 121, nr 19 (7.11.2022): 194102. http://dx.doi.org/10.1063/5.0129651.

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This paper presents an integrated measuring system combining a diamond anvil cell (DAC) and a high overtone bulk acoustic resonator (HBAR) operating at the microwave frequency band as 2.8–8.8 GHz. We have studied several metallic (W, Zr) and semiconductor (Si) samples under pressure up to ∼16 GPa. As an HBAR, we have used the “Al/Al0.72Sc0.28N/Mo/(100) diamond” structure utilizing a piezoelectric aluminum–scandium nitride film. We have observed that under pressure, the Q-factor of the HBAR decreases but remains at the value of 2500–3000, which is suitable for our experiments. It is demonstrated that the above system can be used for studying the behavior of various solids under high pressure, the pressure-induced phase transition in Zr, the registration of plastic deformations, and their relaxation in metals. Here, we discussed the phenomenon of an acoustic wave passing through a tungsten layer under a pressure of ∼5.5 GPa. The integrated DAC&HBAR measuring system has demonstrated some practical advantages over known ultrasonic systems combined with the DAC as the possibility of applying a microwave operational frequency, the measurement of a Q-factor change under pressure, and the miniature size of a sensitive HBAR element. The application of the built-in DAC&HBAR system will hopefully allow more accurate studies on materials in the GPa pressure range of a DAC.

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Alabdulkarim, Mohamad E., Wendy D. Maxwell, Vibhor Thapliyal i James L. Maxwell. "A Comprehensive Review of High-Pressure Laser-Induced Materials Processing, Part III: Laser Reactive Synthesis within Diamond Anvil Cells". Journal of Manufacturing and Materials Processing 7, nr 2 (3.03.2023): 57. http://dx.doi.org/10.3390/jmmp7020057.

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The synthesis of advanced materials at high pressures has been an area of growing research interest for several decades. This article is the third in a three-part series that reviews Laser Materials Processing Within Diamond Anvil Cells (L-DACs). Part III focuses on the practice of Laser Reactive Synthesis Within Diamond Anvil Cells (LRS-DAC). During LRS-DAC processing, chemicals are precompressed within diamond anvil cells, then microscale chemical reactions are induced by focused laser beams. The method is distinguished from the well-known Laser-Heated Diamond Anvil Cell (LH-DAC) technique (see Part I) through the existence of chemical precursors (reactants), end-products, and quantifiable changes in chemical composition upon reaction. LRS-DAC processing provides at least three new degrees of freedom in the search for advanced materials (beyond adjusting static pressures and temperatures), namely: laser-excitation/cleavage of chemical bonds, time-dependent reaction kinetics via pulsed lasers, and pressure-dependent chemical kinetics. All of these broaden the synthetic phase space considerably. Through LRS-DAC experimentation, it is possible to obtain increased understanding of high-pressure chemical kinetics—and even the nature of chemical bonding itself. Here, LRS-DAC experimental methods are reviewed, along with the underlying chemistry/physics of high-pressure microchemical reactions. A chronology of key events influencing the development of LRS-DAC systems is provided, together with a summary of novel materials synthesised, and unusual chemical reactions observed. Current gaps in knowledge and emerging opportunities for further research are also suggested.

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Wang, Jia, i Bao Jia Wu. "Thin Film Microcircuit Preparation in a Diamond Anvil Cell". Advanced Materials Research 690-693 (maj 2013): 499–502. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.499.

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An effective and convenient method about molybdenum metal thin film microcircuit was developed on diamond anvil cell(DAC) under high pressure. Alumina film was used as the protective layer and sputtered on DAC. By using this method, we studied the electrical resistance variation about nanoparticles ZnS power up to 36GPa. The reversible phase transition had been reflected clearly by the electrical resistance measurements with sample.

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Chapman, Karena W., Peter J. Chupas, Gregory J. Halder, Joseph A. Hriljac, Charles Kurtz, Benjamin K. Greve, Chad J. Ruschman i Angus P. Wilkinson. "Optimizing high-pressure pair distribution function measurements in diamond anvil cells". Journal of Applied Crystallography 43, nr 2 (2.03.2010): 297–307. http://dx.doi.org/10.1107/s0021889810002050.

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Pair distribution function (PDF) methods have great potential for the study of diverse high-pressure phenomena. However, the measurement of high-quality, high-resolution X-ray PDF data (toQmax > 20 Å−1) remains a technical challenge. An optimized approach to measuring high-pressure total scattering data for samples contained within a diamond anvil cell (DAC) is presented here. This method takes into account the coupled influences of instrument parameters (photon energy, detector type and positioning, beam size/shape, focusing), pressure-cell parameters (target pressure range, DAC type, diamonds, pressure-transmitting media, backing plates, pressure calibration) and data reduction on the resulting PDF. The efficacy of our approach is demonstrated by the high-quality, high-pressure PDFs obtained for representative materials spanning strongly and weakly scattering systems, and crystalline and amorphous samples. These are the highest-resolution high-pressure PDFs reported to date and include those for α-alumina (toQmax = 20 Å−1), BaTiO3(toQmax= 30 Å−1) and pressure-amorphized zeolite (toQmax = 20 Å−1).

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Nakamura, Y., I. Fujishiro, K. Nishibe i H. Kawakami. "Measurement of Physical Properties of Lubricants Under High Pressure by Brillouin Scattering in a Diamond Anvil Cell". Journal of Tribology 117, nr 3 (1.07.1995): 519–23. http://dx.doi.org/10.1115/1.2831284.

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Brillouin scattering spectra and their transverse mode were measured for paraffinic and naphthenic synthetic lubricants, employing a high-pressure diamond anvil cell (DAC). Sound velocity, density, refractive index, and shear modulus under high pressure were obtained. The density obtained from the thermodynamic relation was compared with that from Lorentz-Lorenz‘s formula. The densities were also compared with Dowson‘s density-pressure equation of lubricants. The sound velocity in the transverse mode and shear modulus were obtained for 5P4E up to 2.7 GPa. A slope change in the pressure-sound velocity diagram was confirmed at about 0.3 GPa, which may be associated with crystallizaton of 5P4E, observed through a diamond optical window in the DAC.

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Nanba, T., M. Muneyasu, N. Hiraoka, S. Kaga, G. P. Williams, O. Shimomura i T. Adachi. "Phase transitions of CdS microcrystals under high pressure". Journal of Synchrotron Radiation 5, nr 3 (1.05.1998): 1016–19. http://dx.doi.org/10.1107/s0909049597016002.

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The experiment under high pressure using a diamond anvil cell (DAC) requires the utilization of synchrotron radiation. High-pressure experiments were performed using a DAC on CdS microcrystals, both in the far-IR and in the X-ray regions, in order to study the lattice dynamics and lattice stability concerned with the phase transitions. From these experiments, experimental evidence is presented indicating that a CdS microcrystal of smaller diameter shows a higher transition pressure for lattice transformation under pressure. The origin of such an increase in the transition pressure in the microcrystals is discussed in relation to the surface tension.

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Prins, A. D., I. L. Spain i D. J. Dunstan. "Diamond anvil cell high-pressure techniques for semiconductor research". Semiconductor Science and Technology 4, nr 4 (1.04.1989): 237–38. http://dx.doi.org/10.1088/0268-1242/4/4/011.

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Sahu, P. Ch, N. R. Sanjay Kumar, N. V. Chandra Shekar i N. Subramanian. "An easy to use X-ray collimator for Mao-Bell type diamond anvil cell". Powder Diffraction 21, nr 4 (grudzień 2006): 320–22. http://dx.doi.org/10.1154/1.2362856.

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An incident beam X-ray collimator for Mao-Bell type diamond anvil cell (DAC) has been developed. Alignment of the collimator is carried out in situ while viewing the image of the collimated X-ray spot formed on a thin layer of fluorescent material spread on the diamond anvil culets with the help of a microscope. Special precaution has been taken to meet the radiation safety requirements during alignment and routine use. This collimator is of immense help for laboratory based high pressure X-ray diffraction experiments.

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QIN, X. M., Y. YU, G. M. ZHANG, F. Y. LI, J. LIU i C. Q. JIN. "HIGH-PRESSURE STRUCTURE STUDY OF CuBa2Ca3Cu4O10 + δ SUPERCONDUCTOR". Modern Physics Letters B 19, nr 06 (20.03.2005): 313–16. http://dx.doi.org/10.1142/s0217984905008335.

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In-situ high-pressure energy dispersive X-ray diffraction measurements on CuBa 2- Ca 3 Cu 4 O 10 + δ (Cu-1234) have been performed by using diamond anvil cell (DAC) device with synchrotron radiation. The results suggest that the crystal structure of Cu-1234 superconductor is stable under pressures up to 34 GPa at room temperature. According to the Birch–Murnaghan equation of state, the bulk modulus is obtained to be ~ 150 GPa.

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Yoshida, Masahiro, Kenji Ishii, Ignace Jarrige, Tetsu Watanuki, Kazutaka Kudo, Yoji Koike, Ken'ichi Kumagai i in. "Momentum-resolved resonant inelastic X-ray scattering on a single crystal under high pressure". Journal of Synchrotron Radiation 21, nr 1 (7.12.2013): 131–35. http://dx.doi.org/10.1107/s1600577513028944.

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A single-crystal momentum-resolved resonant inelastic X-ray scattering (RIXS) experiment under high pressure using an originally designed diamond anvil cell (DAC) is reported. The diamond-in/diamond-out geometry was adopted with both the incident and scattered beams passing through a 1 mm-thick diamond. This enabled us to cover wide momentum space keeping the scattering angle condition near 90°. Elastic and inelastic scattering from the diamond was drastically reduced using a pinhole placed after the DAC. Measurement of the momentum-resolved RIXS spectra of Sr2.5Ca11.5Cu24O41at the CuK-edge was thus successful. Though the inelastic intensity becomes weaker by two orders than the ambient pressure, RIXS spectra both at the center and the edge of the Brillouin zone were obtained at 3 GPa and low-energy electronic excitations of the cuprate were found to change with pressure.

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Dubrovinskaia, Natalia, Leonid Dubrovinsky, Natalia Solopova, Artem Abakumov, Anatoly Snigirev, Irina Snigireva, Vitali Prakapenka i Michael Hanfland. "Nanocrystalline diamond (NCD): an insight into structure-property relationships". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C1334. http://dx.doi.org/10.1107/s2053273314086653.

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Nanocrystalline diamond (NCD) is a unique material we produce by direct conversion of glassy carbon into diamond at ca. 20 GPa and 2200 K in a multi anvil press. One of precursor materials we use is commercially available in the form of glassy carbon balls with a diameter of 20 to 50 microns. NCD demonstrates superior mechanical properties (e.g. extremely high yield strength under confining pressure) and has been successfully used for ultra-high static pressure generation (above 600 GPa) in a double-stage diamond anvil cell (DAC) (Ref. 1). To elucidate structure-property relationships in this extremely strong and seemingly inscrutable material we have investigated its microstructure using HRTEM and HAADF-STEM, measured its compressibility by means of synchrotron X-ray diffraction in a DAC, and evaluated its hardness in comparison to that of the hardest known materials - single-crystal diamond and nano-polycrystalline diamond (NPD) (Ref. 2). An additional insight into the volume compressibility was obtained due to X-ray phase contrast micro-imaging using a coherent high-energy synchrotron radiation. The established structure-property relationships will be presented and analyzed.

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29

Zhang, Yanan, Yue Wu, Yonghao Han i Yang Gao. "Water-cooling diamond anvil cells: An approach to temperature–pressure relation in heated experiments". Review of Scientific Instruments 93, nr 10 (1.10.2022): 103904. http://dx.doi.org/10.1063/5.0099202.

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Temperature induced pressure drift in the diamond anvil cell (DAC) is a major issue in high-pressure high-temperature experiments. It is commonly acknowledged that these drifts originate from multiple factors, but no systematic descriptions have been made so far. By introducing an internal water-cooling system in the DAC, we have performed a systematic investigation into temperature induced pressure drifts to reveal the mechanism behind them and to find a proper experimental procedure to achieve minimal pressure variation in DAC’s heating experiment. It is revealed in this experiment that pressure variation during heating processes originates from multiple temperature related factors of the DAC. The variation itself can be considered as a rebalancing process of the compression forces on the sample chamber initiated by the disturbance caused by temperature elevation. It is possible to suppress pressure variation by maintaining the temperature of the DAC body at room temperature to ensure the consistency of compression on the sample chamber. At the same time, the best procedure for the heating experiments is to properly pre-heat the sample chamber equipped with the internal water-cooling system before performing the in situ measurements on the temperature-related properties at the pressurized and heated conditions. Our discovery provides a reliable procedure for the sample heating process in the DAC and helps resolve the complex mystery of the influence of the combination of pressure and temperature in high-pressure high-temperature experiments.

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Skelton, E. F., A. W. Webb, M. W. Schaefer, D. Schiferl, A. I. Katz, H. D. Hochheimer i S. B. Qadri. "X-Ray Diffraction Studies Under Non-Ambient Conditions: Application to Transition-Metal Dichalcogenide Solid Lubricants". Advances in X-ray Analysis 30 (1986): 465–71. http://dx.doi.org/10.1154/s0376030800021625.

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During the past quarter-century, the field of high pressure research has undergone a quiet revolution. This has resulted from the creation and development of the diamond-anvil cell (DAC). Because diamonds are the hardest known materials, the highest static pressures can be attained and indefinitely held in these devices, recent pressure records have surpassed 400 GPa.

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MATSUDA, Y. H., K. UCHIDA, K. ONO, ZIWU JI i S. TAKEYAMA. "DEVELOPMENT OF A PLASTIC DIAMOND ANVIL CELL FOR HIGH PRESSURE MAGNETO-PHOTOLUMINESCENCE IN PULSED HIGH MAGNETIC FIELDS". International Journal of Modern Physics B 18, nr 27n29 (30.11.2004): 3843–46. http://dx.doi.org/10.1142/s0217979204027578.

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A diamond anvil cell (DAC) made of reinforced plastic has been developed for magneto-photoluminescence experiments in pulsed high magnetic fields. Our DAC has a standard and simple structure equipped with a stainless steel gasket. We have made magneto-photoluminescence experiments of CdTe / Cd 0.8 Mn 0.2 Te multiple quantum wells up to 41 T at 4.2 K in the pressure range 0 to 2.3 GPa. We found that the effect of the eddy current heating of the gasket can be negligible small when we use the pulsed field whose duration is a few tens of milliseconds or longer. We have also found that the exciton Zeeman shift strongly depends on the pressure, which can be a manifestation of the enhancement of the sp-d and d-d exchange interactions in the Gd 0.8 Mn 0.2 Te layer by applying high pressures.

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32

Grzechnik, Andrzej, Martin Meven, Carsten Paulmann i Karen Friese. "Combined X-ray and neutron single-crystal diffraction in diamond anvil cells". Journal of Applied Crystallography 53, nr 1 (1.02.2020): 9–14. http://dx.doi.org/10.1107/s1600576719014201.

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It is shown that it is possible to perform combined X-ray and neutron single-crystal studies in the same diamond anvil cell (DAC). A modified Merrill–Bassett DAC equipped with an inflatable membrane filled with He gas has been developed. It can be used on laboratory X-ray and synchrotron diffractometers as well as on neutron instruments. The data processing procedures and a joint structural refinement of the high-pressure synchrotron and neutron single-crystal data are presented and discussed for the first time.

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Halevy, Itzhak, Shlomo Haroush, Yosef Eisen, Ido Silberman, Dany Moreno, Amir Hen, Mike L. Winterrose, Sanjit Ghose i Zhiqiang Chen. "Crystallographic and magnetic structure of HAVAR under high-pressure using diamond anvil cell (DAC)". Hyperfine Interactions 197, nr 1-3 (kwiecień 2010): 135–41. http://dx.doi.org/10.1007/s10751-010-0222-3.

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Kim, J. K., Diego Casa, Xianrong Huang, Thomas Gog, B. J. Kim i Jungho Kim. "Montel mirror based collimating analyzer system for high-pressure resonant inelastic X-ray scattering experiments". Journal of Synchrotron Radiation 27, nr 4 (27.05.2020): 963–69. http://dx.doi.org/10.1107/s1600577520005792.

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Resonant inelastic X-ray scattering (RIXS) is increasingly playing a significant role in studying highly correlated systems, especially since it was proven capable of measuring low-energy magnetic excitations. However, despite high expectations for experimental evidence of novel magnetic phases at high pressure, unequivocal low-energy spectral signatures remain obscured by extrinsic scattering from material surrounding the sample in a diamond anvil cell (DAC): pressure media, Be gasket and the diamond anvils themselves. A scattered X-ray collimation based medium-energy resolution (∼100 meV) analyzer system for a RIXS spectrometer at the Ir L 3-absorption edge has been designed and built to remediate these difficulties. Due to the confocal nature of the analyzer system, the majority of extrinsic scattering is rejected, yielding a clean low-energy excitation spectrum of an iridate Sr2IrO4 sample in a DAC cell. Furthermore, the energy resolution of different configurations of the collimating and analyzing optics are discussed.

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Hsieh, Wen-Pin, Yi-Chi Tsao i Chun-Hung Lin. "Thermal Conductivity of Helium and Argon at High Pressure and High Temperature". Materials 15, nr 19 (26.09.2022): 6681. http://dx.doi.org/10.3390/ma15196681.

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Helium (He) and argon (Ar) are important rare gases and pressure media used in diamond-anvil cell (DAC) experiments. Their thermal conductivity at high pressure–temperature (P-T) conditions is a crucial parameter for modeling heat conduction and temperature distribution within a DAC. Here we report the thermal conductivity of He and Ar over a wide range of high P-T conditions using ultrafast time-domain thermoreflectance coupled with an externally heated DAC. We find that at room temperature the thermal conductivity of liquid and solid He shows a pressure dependence of P0.86 and P0.72, respectively; upon heating the liquid, He at 10.2 GPa follows a T0.45 dependence. By contrast, the thermal conductivity of solid Ar at room temperature has a pressure dependence of P1.25, while a T−1.37 dependence is observed for solid Ar at 19 GPa. Our results not only provide crucial bases for further investigation into the physical mechanisms of heat transport in He and Ar under extremes, but also substantially improve the accuracy of modeling the temperature profile within a DAC loaded with He or Ar. The P-T dependences of the thermal conductivity of He are important to better model and constrain the structural and thermal evolution of gas giant planets containing He.

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Zou, Yong Gang, Xiao Hui Ma, Quan Lin Shi, Guo Jun Liu, Qing Xue Sui i Zhi Min Zhang. "Growth and High Pressure Investigation of (C₆₀)_n@SWNT". Advanced Materials Research 442 (styczeń 2012): 26–30. http://dx.doi.org/10.4028/www.scientific.net/amr.442.26.

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The (C60)n@SWNT (peapod) samples were prepared by vapor diffusion method. We performed the high pressure Raman measurements on the peapod samples by using a Mao-Bell type diamond anvil cell (DAC). In the In situ high pressure experiments, the peapod samples were exposed under UV laser line irradiation. The polymerization of C60 molecules in SWNT cave under both laser irradiation and pressure effects has been studied. The Raman spectra of the released samples from high pressure indicated that C60s form one-dimensional orthorhombic polymer. For the Raman measurements, two different excitation wavelengths were used, 325 nm laser and 830 nm laser.

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37

Nan, Xuan Guo, Gang Peng i Bao Jia Wu. "Finite Element Analysis Route to Achieve Accurate Resistivity Measurements in Diamond Anvil Cell". Advanced Materials Research 669 (marzec 2013): 279–82. http://dx.doi.org/10.4028/www.scientific.net/amr.669.279.

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To have a clear understanding of the effect of electrode resistivity on the in-situ resistivity measurement under high pressure in a diamond anvil cell (DAC), we perform finite element analysis (FEA) to simulate the distribution of the steady current field in sample. The theoretical analysis reveals the origin of the effect. It is caused by the resistivity difference between electrodes and sample. And the more the difference of their resistivity is, the more obvious the effect is. All these will result in large resistivity error. However we find that reducing the resistivity difference between the electrode and sample can improve the results.

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Yao, L. D., S. D. Luo, X. Shen, S. J. You, L. X. Yang, S. J. Zhang, S. Jiang i in. "Structural stability and Raman scattering of InN nanowires under high pressure". Journal of Materials Research 25, nr 12 (grudzień 2010): 2330–35. http://dx.doi.org/10.1557/jmr.2010.0290.

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High-pressure in situ angular dispersive x-ray diffraction study on the wurtzite-type InN nanowires has been carried out by means of the image-plate technique and diamond-anvil cell (DAC) up to about 31.8 GPa. The pressure-induced structural transition from the wurtzite to a rocksalt-type phase occurs at about 14.6 GPa, which is slightly higher than the transition pressure of InN bulk materials (∼12.1 GPa). The relative volume reduction at the transition point is close to 17.88%, and the bulk modulus B0 is determined through fitting the relative volume-pressure experimental data related to the wurtzite and rocksalt phases to the Birch–Murnaghan equation of states. Moreover, high-pressure Raman scattering for InN nanowires were also investigated in DAC at room temperature. The corresponding structural transition was confirmed by assignment of phonon modes. We calculated the mode Grüneisen parameters for the wurtzite and rocksalt phases of InN nanowires.

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Schaeffer, Anne Marie, Scott R. Temple, Jasmine K. Bishop i Shanti Deemyad. "High-pressure superconducting phase diagram of 6Li: Isotope effects in dense lithium". Proceedings of the National Academy of Sciences 112, nr 1 (23.12.2014): 60–64. http://dx.doi.org/10.1073/pnas.1412638112.

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We measured the superconducting transition temperature of 6Li between 16 and 26 GPa, and report the lightest system to exhibit superconductivity to date. The superconducting phase diagram of 6Li is compared with that of 7Li through simultaneous measurement in a diamond anvil cell (DAC). Below 21 GPa, Li exhibits a direct (the superconducting coefficient, α, Tc∝M−α, is positive), but unusually large isotope effect, whereas between 21 and 26 GPa, lithium shows an inverse superconducting isotope effect. The unusual dependence of the superconducting phase diagram of lithium on its atomic mass opens up the question of whether the lattice quantum dynamic effects dominate the low-temperature properties of dense lithium.

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40

Sahle, Ch J., A. D. Rosa, M. Rossi, V. Cerantola, G. Spiekermann, S. Petitgirard, J. Jacobs, S. Huotari, M. Moretti Sala i A. Mirone. "Direct tomography imaging for inelastic X-ray scattering experiments at high pressure". Journal of Synchrotron Radiation 24, nr 1 (1.01.2017): 269–75. http://dx.doi.org/10.1107/s1600577516017100.

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A method to separate the non-resonant inelastic X-ray scattering signal of a micro-metric sample contained inside a diamond anvil cell (DAC) from the signal originating from the high-pressure sample environment is described. Especially for high-pressure experiments, the parasitic signal originating from the diamond anvils, the gasket and/or the pressure medium can easily obscure the sample signal or even render the experiment impossible. Another severe complication for high-pressure non-resonant inelastic X-ray measurements, such as X-ray Raman scattering spectroscopy, can be the proximity of the desired sample edge energy to an absorption edge energy of elements constituting the DAC. It is shown that recording the scattered signal in a spatially resolved manner allows these problems to be overcome by separating the sample signal from the spurious scattering of the DAC without constraints on the solid angle of detection. Furthermore, simple machine learning algorithms facilitate finding the corresponding detector pixels that record the sample signal. The outlined experimental technique and data analysis approach are demonstrated by presenting spectra of the SiL2,3-edge and OK-edge of compressed α-quartz. The spectra are of unprecedented quality and both the OK-edge and the SiL2,3-edge clearly show the existence of a pressure-induced phase transition between 10 and 24 GPa.

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41

LaPlant, F., E. J. Hutchinson i D. Ben-Amotz. "Raman Measurements of Localized Pressure Variations in Lubricants Above the Glass Transition Pressure". Journal of Tribology 119, nr 4 (1.10.1997): 817–22. http://dx.doi.org/10.1115/1.2833891.

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Spatial pressure variations in synthetic lubricants contained in a static high-pressure diamond anvil cell (DAC), as well as in a loaded model bearing contact device, have been measured using the frequency shift of the lubricant’s Raman vibrational modes. Long-lived pressure fluctuations of ±0.5 GPa, with a relaxation time of several days, are observed m the static high pressure systems at an average pressure of 2.5 GPa. Evidence for rapidly varying pressure fluctuations in a concentrated contact is inferred from the increase in lubricant Raman linewidths. These results raise questions about key assumptions made in modeling EHD contacts. It is suggested that the present results are closely linked to recent observations of shear localization made by Winer and Bair.

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Liermann, H. P., Z. Konôpková, K. Appel, C. Prescher, A. Schropp, V. Cerantola, R. J. Husband i in. "Novel experimental setup for megahertz X-ray diffraction in a diamond anvil cell at the High Energy Density (HED) instrument of the European X-ray Free-Electron Laser (EuXFEL)". Journal of Synchrotron Radiation 28, nr 3 (14.04.2021): 688–706. http://dx.doi.org/10.1107/s1600577521002551.

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The high-precision X-ray diffraction setup for work with diamond anvil cells (DACs) in interaction chamber 2 (IC2) of the High Energy Density instrument of the European X-ray Free-Electron Laser is described. This includes beamline optics, sample positioning and detector systems located in the multipurpose vacuum chamber. Concepts for pump–probe X-ray diffraction experiments in the DAC are described and their implementation demonstrated during the First User Community Assisted Commissioning experiment. X-ray heating and diffraction of Bi under pressure, obtained using 20 fs X-ray pulses at 17.8 keV and 2.2 MHz repetition, is illustrated through splitting of diffraction peaks, and interpreted employing finite element modeling of the sample chamber in the DAC.

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Xiong, Lun, Bin Li, Bi Liang, Jinxia Zhu, Hong Yi i Junran Zhang. "A high-pressure study of HfC and nano-crystalline TiC by X-ray diffraction and density functional theory calculations". Modern Physics Letters B 34, nr 34 (15.08.2020): 2050393. http://dx.doi.org/10.1142/s0217984920503935.

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The equation of state (EOS) of HfC and nanosized TiC at high pressure has been studied by means of synchrotron radiation X-ray diffraction (XRD) in a diamond anvil cell (DAC) at ambient temperature, and density functional theory (DFT) calculations. XRD analysis showed that the cubic structure of HfC and nanosized TiC maintained to the maximum pressures. The XRD data yield a bulk modulus [Formula: see text] GPa with [Formula: see text] of HfC. In addition, the bulk modulus of nanosized TiC derived from XRD data is [Formula: see text] GPa with [Formula: see text].

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Zhang, Congyan, Uttam Bhandari, Congyuan Zeng, Huan Ding, Shengmin Guo, Jinyuan Yan i Shizhong Yang. "Carbide Formation in Refractory Mo15Nb20Re15Ta30W20 Alloy under a Combined High-Pressure and High-Temperature Condition". Entropy 22, nr 7 (28.06.2020): 718. http://dx.doi.org/10.3390/e22070718.

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In this work, the formation of carbide with the concertation of carbon at 0.1 at.% in refractory high-entropy alloy (RHEA) Mo15Nb20Re15Ta30W20 was studied under both ambient and high-pressure high-temperature conditions. The x-ray diffraction of dilute carbon (C)-doped RHEA under ambient pressure showed that the phases and lattice constant of RHEA were not influenced by the addition of 0.1 at.% C. In contrast, C-doped RHEA showed unexpected phase formation and transformation under combined high-pressure and high-temperature conditions by resistively employing the heated diamond anvil cell (DAC) technique. The new FCC_L12 phase appeared at 6 GPa and 809 °C and preserved the ambient temperature and pressure. High-pressure and high-temperature promoted the formation of carbides Ta3C and Nb3C, which are stable and may further improve the mechanical performance of the dilute C-doped alloy Mo15Nb20Re15Ta30W20.

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Jennings, Eleanor S., Jon Wade, Vera Laurenz i Sylvain Petitgirard. "Diamond Anvil Cell Partitioning Experiments for Accretion and Core Formation: Testing the Limitations of Electron Microprobe Analysis". Microscopy and Microanalysis 25, nr 1 (22.01.2019): 1–10. http://dx.doi.org/10.1017/s1431927618015568.

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AbstractMetal–silicate partitioning studies performed in high-pressure, laser-heated diamond anvil cells (DAC) are commonly used to explore element distribution during planetary-scale core–mantle differentiation. The small run-products contain suitable areas for analysis commonly less than tens of microns in diameter and a few microns thick. Because high spatial resolution is required, quantitative chemical analyses of the quenched phases is usually performed by electron probe microanalysis (EPMA). Here, EPMA is being used at its spatial limits, and sample thickness and secondary fluorescence effects must be accounted for. By using simulations and synthetic samples, we assess the validity of these measurements, and find that in most studies DAC sample wafers are sufficiently thick to be characterized at 15 kVacc. Fluorescence from metal-hosted elements will, however, contaminate silicate measurements, and this becomes problematic if the concentration contrast between the two phases is in excess of 100. Element partitioning experiments are potentially compromised; we recommend simulating fluorescence and applying a data correction, if required, to such DAC studies. Other spurious analyses may originate from sources external to the sample, as exemplified by 0.5 to >1 wt% of Cu arising from continuum fluorescence of the Cu TEM grid the sample is typically mounted on.

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Henry, Laura, Volodymyr Svitlyk, Gaston Garbarino, David Sifre i Mohamed Mezouar. "Structure of solid chlorine at 1.45 GPa". Zeitschrift für Kristallographie - Crystalline Materials 234, nr 4 (24.04.2019): 277–80. http://dx.doi.org/10.1515/zkri-2018-2145.

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Abstract Single crystals of solid chlorine (Cl2) were synthesized at room temperature and high pressure (HP, P=1.45 GPa) in a diamond anvil cell (DAC). At these conditions Cl2 adapts the same structure as its corresponding low-temperature (LT) ambient pressure modification (T<172 K), as concluded from HP single crystal diffraction experiments. Namely, it crystallizes in an orthorhombic symmetry (Cmce spacegroup) with Cl2 molecules forming monolayers parallel to the bc plane and this structure is preserved up to at least 64 GPa. The pressure of 1.45 GPa is to be considered as a solidification point of liquid Cl2 at room temperature.

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Tchoń, D., i A. Makal. "Maximizing completeness in single-crystal high-pressure diffraction experiments: phase transitions in 2°AP". IUCrJ 8, nr 6 (15.10.2021): 1006–17. http://dx.doi.org/10.1107/s2052252521009532.

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Sufficiently high completeness of diffraction data is necessary to correctly determine the space group, observe solid-state structural transformations or investigate charge density distribution under pressure. Regrettably, experiments performed at high pressure in a diamond anvil cell (DAC) yield inherently incomplete datasets. The present work systematizes the combined influence of radiation wavelength, DAC opening angle and sample orientation in a DAC on the completeness of diffraction data collected in a single-crystal high-pressure (HP) experiment with the help of dedicated software. In particular, the impact of the sample orientation on the achievable data completeness is quantified and proved to be substantial. Graphical guides for estimating the most beneficial sample orientation depending on the sample Laue class and assuming a few commonly used experimental setups are proposed. The usefulness of these guides has been tested in the case of luminescent 1,3-diacetylpyrene, suspected to undergo transitions from the α phase (Pnma) to the γ phase (Pn21 a) and δ phase (P1121/a) under pressure. Effective sample orientation has ensured over 90% coverage even for the monoclinic system and enabled unrestrained structure refinements and access to complete systematic extinction patterns.

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Wang, Zhongwu, i T. Yagi. "Incorporation of ferric iron in CaSiO3 perovskite at high pressure". Mineralogical Magazine 62, nr 5 (październik 1998): 719–23. http://dx.doi.org/10.1180/002646198547963.

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AbstractSynthetic andradite (Ca3Fe2Si3O12) has been compressed to loading pressures >21 GPa and heated to ∼1000°C by a YAG laser in a Diamond Anvil Cell (DAC). After quenching to room temperature, X-ray diffraction of the sample, still held at 21 GPa, showed that andradite had transformed to a cubic perovskite type polymorph with a = 3.460(4) Å. Upon decompression the perovskite phase transformed into an amorphous phase. The density of the perovskite polymorph (Ca3Fe2Si3O12) is ∼13.6% greater than that of isochemical andradite at 21 GPa. Ferric iron replaces Ca2+ and Si4+ in the perovskite structure (Fe3+ + Fe3+ = Si4+ + Ca2+), giving a formula unit: (Ca,Fe3+)(Si,Fe3+)O3. The new Fe3+-rich Ca-perovskite may provide new insight into the controls on the electrical conductivity of the lower mantle.

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Kuznetsov, A. Yu, L. Dubrovinsky, A. Kurnosov, M. M. Lucchese, W. Crichton i C. A. Achete. "High-Pressure Synthesis and Study of NO+NO3− and NO2+NO3− Ionic Solids". Advances in Physical Chemistry 2009 (4.01.2009): 1–11. http://dx.doi.org/10.1155/2009/180784.

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Nitrosonium-nitrate NO+NO3− and dinitrogen pentoxide NO2+NO3− ionic crystals were synthesized by laser heating of a condensed oxygen-rich O2-N2 mixture compressed to different pressures, up to 40 GPa, in a diamond anvil cell (DAC). High-pressure/high-temperature Raman and X-ray diffraction studies of synthesized samples disclosed a transformation of NO+NO3− compound to NO2+NO3− crystal at temperatures above ambient and pressures below 9 GPa. High-pressure experiments revealed previously unreported bands in Raman spectra of NO+NO3− and NO2+NO3− ionic crystals. Structural properties of both ionic compounds are analyzed. Obtained experimental results support a hypothesis of a rotational disorder of NO+ complexes in NO+NO3− and indicate a rotational disorder of ionic complexes in NO2+NO3− solid.

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Rillo, Giovanni, Miguel A. Morales, David M. Ceperley i Carlo Pierleoni. "Optical properties of high-pressure fluid hydrogen across molecular dissociation". Proceedings of the National Academy of Sciences 116, nr 20 (30.04.2019): 9770–74. http://dx.doi.org/10.1073/pnas.1818897116.

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Optical properties of compressed fluid hydrogen in the region where dissociation and metallization is observed are computed by ab initio methods and compared with recent experimental results. We confirm that at T > 3,000 K, both processes are continuous, while at T < 1,500 K, the first-order phase transition is accompanied by a discontinuity of the dc conductivity and the thermal conductivity, while both the reflectivity and absorption coefficient vary rapidly but continuously. Our results support the recent analysis of National Ignition Facility (NIF) experiments [Celliers PM, et al. (2018) Science 361:677–682], which assigned the inception of metallization to pressures where the reflectivity is ∼0.3. Our results also support the conclusion that the temperature plateau seen in laser-heated diamond-anvil cell (DAC) experiments at temperatures higher than 1,500 K corresponds to the onset of optical absorption, not to the phase transition.

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