Pressure In Diamond Anvil Cell Research Articles

Atomic and itinerant effects at the transition-metal x-ray absorptionKpre-edge exemplified in the case of V2O3

X-ray absorption spectroscopy is a well-established tool for obtaining information about orbital and spin degrees of freedom in transition-metal and rare-earth compounds. For this purpose usually the dipole transitions of the $L$ ($2p$ to $3d$) and $M$ ($3d$ to $4f$) edges are employed, whereas higher order transitions such as quadrupolar $1s$ to $3d$ in the $K$ edge are rarely studied in that respect. This is due to the fact that usually such quadrupolar transitions are overshadowed by dipole-allowed $1s$ to $4p$ transitions and, hence, are visible only as minor features in the pre-edge region. Nonetheless, these features carry a lot of valuable information, similar to the dipole $L$-edge transition, which is not accessible in experiments under pressure due to the absorption of the diamond anvil pressure cell. We recently performed a theoretical and experimental analysis of such a situation for the metal-insulator transition of (V${}_{(1\ensuremath{-}x)}$Cr${}_{x}$)${}_{2}$O${}_{3}$. Since the importance of the orbital degrees of freedom in this transition is widely accepted, a thorough understanding of quadrupole transitions of the vanadium $K$ pre-edge provides crucial information about the underlying physics. Moreover, the lack of inversion symmetry at the vanadium site leads to on-site mixing of vanadium $3d$ and $4p$ states and related quantum mechanical interferences between dipole and quadrupole transitions. Here we present a theoretical analysis of experimental high-resolution x-ray absorption spectroscopy at the V $K$ pre-edge measured in partial fluorescence yield mode for single crystals. We carried out density functional as well as configuration interaction calculations in order to capture effects coming from both itinerant and atomic limits.

Comparison between beryllium and diamond-backing plates in diamond-anvil cells: Application to single-crystal x-ray diffraction high-pressure data

A direct comparison between two complete intensity datasets, collected on the same sample loaded in two identical diamond-anvil pressure cells equipped, respectively, with beryllium and diamond-backing plates was performed. The results clearly demonstrate that the use of diamond-backing plates significantly improves the quality of crystal structure data. There is a decrease in the internal R factor for averaging, structure refinement agreement factors, and in the errors and uncertainties of the atomic coordinates, atomic displacement parameters, and individual bond lengths.

SINGLE: a program to control single-crystal diffractometers

SINGLE, a program that runs under Windows operating systems, can be used to control a variety of four-circle Eulerian-cradle single-crystal diffractometers including Huber instruments equipped with Huber motor controllers, the Stoe Stadi-4 and the Siemens P4. The software can be configured,viavariables set by the user, to operate any of these diffractometers with a variety of environmental devices including furnaces and diamond-anvil pressure cells. It is specifically designed to determine unit-cell parameters to a precision of 1 part in 30 000.

Effects of deviatoric stresses in the diamond-anvil pressure cell on single-crystal samples

The nonhydrostatic stress states that are developed in the pressure media within diamond-anvil pressure cells have been investigated by single-crystal X-ray diffraction. Measurements of unit-cell parameters of small single crystals under nonhydrostatic conditions are used to calculate the deviatoric strains and, through knowledge of the elastic tensors of the crystals, the stress state of the media. The results confirm that the stress state is effectively cylindrically symmetrical with the stress parallel to the load axis being greater than the radial stresses. The stress state in a given medium can be predicted and can be used to design a specific response of the lattice parameters of small single crystals to pressure beyond the hydrostatic pressure limit of the pressure medium.

Rheology and nonhydrostatic pressure evaluation of solidified oils including Daphne oils by observing microsphere deformation

The rheological properties of solidified oils including Daphne 7373 and 7474 under high pressure up to 5 GPa were evaluated by observing the large plastic deformation of metal microspheres due to nonhydrostatic pressurization in these oils using a diamond-anvil pressure cell. The solidification pressures determined by the onset pressures of deformation for aluminum microspheres are about 0.6 GPa for traction oils, 1.2 GPa for mineral oils, and 1.79 GPa for Daphne 7373 at 24 °C. Microsphere deformation for Daphne 7474 was not observed up to 3.51 GPa. Shear stresses of the solidified oils were estimated from the deformed Cu microspheres, treating them as stress sensors based on several assumptions.

S1107-1-1 固化潤滑油およびグリースの超高圧レオロジー特性新評価法([S1107-1]トライボロジーにおける実験・計測・解析手法の新展開)

High-pressure rheological properties of solidified lubricant oils and greases were evaluated by an originally proposed new method, that is, the large plastic deformation analysis of metal microspheres (about 0.07 mm) in these lubricants, occurring due to non-hydrostatic pressurization of a diamond-anvil pressure cell. The solidification pressures obtained by observing aluminum sphere deformation were 0.2-0.7 GPa for traction grease and oils, 1.3-1.8 GPa for synthetic base oils and their urea or lithium greases including ionic liquid and recent aerospace lubricants. The solidification pressures were almost the same values among base oils and their greases. By substituting the solidification pressures and pressure-viscosity coefficients in the Barus equation, viscosities at the solidification pressure were obtained. The values were different for each oil and were within the order of 10^4〜10^7 Pas. Based on several assumptions, rough equivalent traction coefficients of the solidified oils could be estimated up to 4 GPa.

High Pressure Phase Diagram of the Non-centrosymmetric Antiferromagnet CeCoGe3

We present a detailed study of the high pressure phase diagram of the non-centrosymmetric antiferromagnet CeCoGe 3 by measurements of the ac calorimetry in a diamond anvil pressure cell. Under high pressure the magnetic ordering temperature shows a step like decrease due to various successive magnetic phases under high pressure. The magnetic order disappears at a critical pressure of p c ≈5.5 GPa. Around the critical pressure bulk superconductivity has been detected in the ac calorimetric measurement.

High-pressure transport and microcalorimetry studies on high qualityYbCu2Si2single crystals

We report electrical transport and calorimetry studies on high quality single crystals of ${\text{YbCu}}_{2}{\text{Si}}_{2}$ under pressure in diamond and Bridgman anvil pressure cells with liquid pressure-transmitting media. At ambient pressure, in the best samples we find residual resistivities of less than $0.5\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$. We have also determined the anisotropy of the temperature dependence of the resistivity and shown that this can account for sample-dependent differences of the resistivity. We confirm the previously reported transition to a magnetically ordered ground state with pressure and we have precisely determined the $(p,T)$ phase diagram using pure samples, good hydrostatic pressure conditions, and calorimetry measurements. Above 8.8 GPa we see a clear signature of the transition in the specific heat. We discuss the low-temperature resistivity and specific-heat behaviors in respect to the universal Kadowaki Woods ratio, to other ytterbium-based strongly correlated systems, and to the cerium-based counterpart, ${\text{CeCu}}_{2}{\text{Si}}_{2}$.

Rheological Study of Solidified Traction Oils under High Pressure by Observation of Deformed Microspheres

The rheological properties of solidified traction oils used in continuously variable transmissions (CVTs) under pressure were evaluated by observing large plastic deformation of metal microspheres (φ about 0.07 mm), occurring due to non-hydrostatic pressurization in these oils using a diamond-anvil pressure cell. The solidification pressure values obtained by observing aluminum sphere deformation were almost equal to those extrapolated from high-pressure viscosity; thus, aluminum sphere deformation experiments are effective for evaluating solidification pressure. Shear stresses of the solidified oils could be estimated up to 5 GPa from the deformed Cu spheres based on several assumptions. The stresses were almost equal to the mean shear stress obtained from a traction test between 1.0 GPa and 1.7 GPa and were below it for pressures above 1.7 GPa. The stress values varied little among different oils.

1203 潤滑油およびトラクション油の高圧粘度測定(すべり及び動力伝達性能,一般講演)

High-pressure viscosity was measured for lubricant oils including a traction CVT oil up to 2.7 GPa at elevated temperature up to 200℃ employing a falling sphere method in a diamond-anvil pressure cell (DAC). The obtained relations between logarithmic viscosity and pressure at all temperature (40℃〜200℃) showed the non-linearity with some data scattering. Therefore, viscosity-pressure coefficient α was not constant and decreased with pressure for lubricant oils and increased for a traction CVT oil. α was also dependent on temperature. These dependence should be considered for EHL oil film thickness analyses concerning fatigue life of machine elements. A pressure temperature phase diagram of liquid-solid transition was plotted from the obtained high pressure viscosity, which predicts traction feature.

3103 トラクションCVT油の高圧固化レオロジー特性評価(S40-1 第14回卒業研究コンテスト(1),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

The rheological properties of a solidified traction oil used in continuously variable transmissions (CVTs) under pressure were evaluated by observing large plastic deformation of metal microspheres (φ about 0.07 mm), occurring due to non-hydrostatic pressurization in the oil using a diamond-anvil pressure cell. The solidification pressure values obtained by observing aluminum sphere deformation were almost equal to those extrapolated from high-pressure viscosity; thus, aluminum sphere deformation experiments are effective for evaluating solidification pressure. Shear stresses of the solidified oils could be estimated up to 5 GPa from the deformed phosphor bronze spheres based on several assumptions. The obtained stresses were larger than those for Cu spheres and were almost equal to the mean shear stress obtained from a traction test.

3001 2GPaまでの潤滑油高圧粘度簡易測定のための基礎実験(S56-1 第13回卒業研究コンテスト(1),S56 第13回卒業研究コンテスト)

Nakamura et. al. had enabled simple measurements of lubricant high-pressure viscosity up to 0.8GPa using a diamond-anvil pressure cell (DAC) by establishing a pressure calibration diagram with a loading screw angle of the DAC. In the present study, the applicability of this method up to 2GPa was investigated by measuring high-pressure viscosity for several alcohols and an ester oil whose viscosity data was reported by Bridgman up to 3GPa. A pressure calibration diagram was constructed, which was proved to be independent of liquids with confirming reproducibility. Employing this pressure calibration diagram, high-pressure viscosities were obtained for some alcohols and they were consistent with Bridgman data up to 2GPa with some data scatters.

Pressure induced magnetic ordering in [formula omitted

In order to investigate pressure-induced magnetically ordered phase in YbInCu 4 , the DC magnetization has been measured up to 7.57 GPa by using the combined system of a diamond-anvil pressure cell and a superconducting quantum interference device (SQUID) with a vibrating coil magnetometer. In the pressure range above 3.05 GPa, a rapid increase in the magnetization below T M = 2.5 K was observed, giving the first direct evidence of spontaneous magnetization in the high pressure phase of YbInCu 4 . T M shows weak pressure dependence up to the maximum pressure of 7.57 GPa. A phase diagram for YbInCu 4 over a wide range of pressure is presented.

Pressure effect of electrical resistivity and AC specific heat in CePtAl

We measured the electrical resistivity and AC-specific heat for a canted ferromagnet CePtAl under pressures using a diamond-anvil pressure cell. With increasing pressure, the magnetic ordering temperature T C 1 increases monotonously, becomes constant above 8 GPa and then starts to decrease steeply in a narrow pressure region from 10.3 to 10.9 GPa , indicating the first-order like phase transition. The similar pressure dependence of T C 1 was obtained in the AC-specific heat measurement.

Pressure effect on luminescence dynamics inPr3+-dopedLiNbO3 and LiTaO3 crystals

The luminescence kinetics of LiNbO3:Pr3+ and LiTaO3:Pr3+ have been measured under high hydrostatic pressure applied in a diamond anvil cell forpressures up to 200 kbar. The luminescence decays have been analysed using the continuousfunction decay times distribution. Two mechanisms that accelerate the emission decayswith increasing pressure have been proposed: the non-radiative depopulation of the1D2 state through thePr3+ trapped exciton,dominating in LiNbO3:Pr3+ and pressure-induced increase of the transition probability, dominating inLiTaO3:Pr3+.

High-pressure and -temperature viscosity measurements of methanol and 4:1 methanol:ethanol solution

Viscosity (eta) measurements using rolling sphere viscometry in a resistance-heated diamond-anvil pressure cell yield activation energies of 18-98 kJmol over a pressure range of 1.1-6.1 GPa for methanol and 26-78 kJmol over a pressure range of 2.9-5.4 GPa for a 4:1 methanol:ethanol solution. Nonlinear models of log eta (free-volume and power-law models) yield statistically better fits than the Arrhenius model at room temperature and extrapolate to lower glass-transition (10(12) Pa s) pressures. Glass-transition pressures for the free-volume model change little over the temperature range studied (298-338 K), whereas the power-law values converge to those of the Arrhenius model at temperatures above 320 K.

Structural changes induced by lattice–electron interactions: SiO2stishovite and FeTiO3ilmenite

The bright source and highly collimated beam of synchrotron radiation offers many advantages for single-crystal structure analysis under non-ambient conditions. The structure changes induced by the lattice-electron interaction under high pressure have been investigated using a diamond anvil pressure cell. The pressure dependence of electron density distributions around atoms is elucidated by a single-crystal diffraction study using deformation electron density analysis and the maximum entropy method. In order to understand the bonding electrons under pressure, diffraction intensity measurements of FeTiO3 ilmenite and gamma-SiO2 stishovite single crystals at high pressures were made using synchrotron radiation. Both diffraction studies describe the electron density distribution including bonding electrons and provide the effective charge of the cations. In both cases the valence electrons are more localized around the cations with increasing pressure. This is consistent with molecular orbital calculations, proving that the bonding electron density becomes smaller with pressure. The thermal displacement parameters of both samples are reduced with increasing pressure.

Single-crystal synchrotron X-ray diffraction study of wüstite and magnesiowüstite at lower-mantle pressures

This study demonstrates the use of monochromatic synchrotron X-ray radiation of 40 keV for high-precision equation-of-state studies on sets of single crystals analysed individually in the same diamond-anvil pressure cell. Angle-dispersive zone-axis diffraction patterns were obtained from crystals of wustite-Fe0.93O and magnesiowüstite-(Mg0.73Fe0.27)O to 51 GPa in a hydrostatic helium pressure medium. The rhombohedral phase of Fe0.93O was observed above 23 GPa, and its isothermal bulk modulus (K0) was determined to be 134 (+/-4) GPa, assuming K'=4. The rhombohedral phase of Fe(0.93)O is more compressible than B1-structured Fe0.93O, with K0=146 (+/-2) GPa. Magnesiowüstite-(Mg0.73Fe0.27)O remains cubic over the experimental pressure range, and has a bulk modulus of 154 (+/-3) GPa with K'=4.0 (+/-0.1).

Progress in the realization of a practical pressure scale for the range 1–300 GPa

X-ray diffraction measurements on diamond and various metals under hydrostatic pressures up to ∼140 GPa together with determinations of ruby luminescence line shifts provide new constraints for the refinement of a practical pressure scale based on either the ruby line shift or the X-ray diffraction with the given calibrants. Implications for other high-pressure studies with diamond anvil pressure cells as well as for theoretical high-pressure studies and for equation of state forms are discussed.

Micro-rheometry of pressurized lubricants and micro-nanorheology

In the present study, micro-rheometry of pressurized lubricants employing a diamond-anvil pressure cell and a laser confocal displacement sensor of 0.4 μm resolution was shown. High pressure viscosity was obtained up to 2 GPa at 200°C for traction oils and PFPE oils. The linearity between logarithmic viscosity and pressure is confirmed. Viscosity-pressure coefficient α at room temperature was almost twice larger than that at 100°C. α for hard disk oil, Zdol2000, was 13/GPa at 24°C ~ 5/GPa at 150°C and was similar to that of paraffinic mineral oil. The feature of the obtained high pressure volume was different for each oil up to 6 GPa. Zdol2000 was the most compressible of all the sample lubricants and its high pressure refractive index increased about 10% at 4.8 GPa. Zdol2000 remained transparent up to 4.8 GPa under isothermal loading. Some considerations for lubricant’s micro-nanorheology were also mentioned with high pressure lubricant’s rheology.