Diamond-anvil Technique Research Articles

High-pressure Raman and FTIR studies of solid potassium, rubidium and caesium hydroxides

Effects of compression on the Raman and IR modes of KOH(D), RbOH(D) and CsOH(D) have been measured at pressures up to 20 GPa and temperatures down to 100 K using the diamond anvil technique. For all three hydroxides an ordering transition into the respective hydrogen-bonded low-temperature phases was found below 1 GPa at room temperature. In addition, the spectra of KOH(D) and RbOH(D) show significant changes at pressures above 6.5 GPa, which point to the existence of a new phase. The decrease in frequency of the IR- and Raman-active O-H(D) stretching vibrations with increasing compression indicates that hydrogen bonds exist also in the new high-pressure phase VI. The variation of the 0-0 distance at the phase transition IV implies VI is estimated by using a double-minimum potential.

BP at megabar pressures and its equation of state to 110 GPa

Energy-dispersive x-ray-diffraction studies were carried out on the III-V compound BP to megabar pressures using diamond-anvil techniques and a high-energy synchrotron x-ray source. The BP sample remained stable in its zinc-blende phase to at least 110 GPa, the upper pressure limit of this experiment. The equation-of-state and Birch coefficients of BP were obtained from this experiment. The measured bulk modulus of BP is slightly lower than the value obtained in recent theoretical calculations based on the total energy pseudopotential method within the local-density approximation.

「ガスケット」の話 ダイヤモンドアンビルの基礎技術

Selection and machining of a gasket is the base of diamond anvil technique. Mechnical property of the gasket material primarily affects to the thickness of the sample chamber. The way of selection and the machining of the gasket, as well as the compression technique of diamond anvil, are described.

Raman and FTIR study of NaOH and NaOD under pressure

The effect of pressure on the Raman and IR modes of NaOH and NaOD have been measured for pressures up to 25 GPa and temperatures down to 100 K, using the diamond anvil technique. Changes in the Raman and IR spectra indicate transformations into different structures. The results reveal that the phase diagrams of NaOH and NaOD are very similar and show only small differences in the respective transition pressures.

Compressibility of M3C60Fullerene Superconductors: Relation BetweenTcand Lattice Parameter

X-ray diffraction and diamond anvil techniques were used to measure the isothermal compressibility of K(3)C(60) and Rb(3)C(60), the superconducting, binary alkali-metal intercalation compounds of solid buckminsterfullerene. These results, combined with the pressure dependence of the superconducting onset temperature T(c) measured by other groups, establish a universal first-order relation between T(c) and the lattice parameter a over a broad range, between 13.9 and 14.5 angstroms. A small secondorder intercalate-specific effect was observed that appears to rule out the participation of intercalate-fullerene optic modes in the pairing interaction.

On peculiarities of plastic loosening of gasket materials at pressure generation by diamond anvil technique

Abstract In this paper standard gasket materials are studied to estimate the plastic loosening intensity at the deformation centre during uniaxial compression in the diamond-anvil high-pressure apparatus using the mathematical model of plastic yield and stress-strain state parameters of metallic gaskets.

Transuranium materials under extreme pressures

The diamond anvil technique and its potential are briefly introduced. A few results of high-pressure study of transuranium metals and compounds are described.

Electronic structure of the high-pressure modifications of CuCl, CuBr, and CuI.

The absorption spectra of edge excitons in thin films of CuCl, CuBr, and CuI have been measured as a function of hydrostatic pressure using the diamond-anvil technique. The measurements yield the pressure dependence of several exciton energies in the zinc-blende, the rhombohedral, and the tetragonal modifications of the copper halides. The experimental data are compared with band-structure calculations performed with the linear-muffin-tin-orbital method. The valence bands of the rhombohedral and tetragonal phases of the copper halides are strongly influenced by the hybridization of copper 3d and halogen p states. This p-d hybridization is allowed by symmetry for all points of the Brillouin zone in all modifications studied. The edge excitons are interpreted as related to direct transitions at k=0 between valence bands split by ligand-field and spin-orbit effects and an orbital singlet conduction band.

Recent studies of phase equilibria at high pressures

In its first part the present review considers the dependence of phase transition temperatures of some selected liquid crystals on pressure up to 300 MPa with differential thermal analysis (DTA) and diamond anvil techniques; here also pressure-induced phases as well as tricritical and reentrant phenomena will be discussed. In the second part the most important types of high-pressure phase diagrams of fluid mixtures are shortly reviewed. Here recent results on binary systems (containing trifluoromethane, tetrafluoromethane, nitrogen etc) will be presented and compared with data that are calculated from an equation of state. The results will be discussed in relation to some applications e.g. in fluid extraction and supercritical fluid chromatography (SFC).

Melting of sodium and potassium in a diamond anvil cell.

Melting temperatures of sodium and potassium to 110 and 145 kbar, respectively, were determined by optical property changes with an externally heated diamond anvil cell using mineral oil as the pressure medium. The pressure was obtained from the known pressure and temperature shifts of the ruby fluorescence line. Sodium shows a continuous rise in the melting temperatures with pressure. The melting temperature of potassium remains nearly constant above about 70 kbar and the melting curve changes its slope drastically at 110 kbar. This is attributed to the bcc-fcc phase transformation that has been recently reported at room temperature around 110 kbar using the diamond anvil technique.

Metallic Xenon at Static Pressures

Using a diamond indentor, diamond anvil technique along with nonshorting interdigitated electrodes produced on the anvil by lithographic processes, we have shown that the electrical resistance of a xenon sample at 32\ifmmode^\circ\else\textdegree\fi{}K drops from ${10}^{13}$ \ensuremath{\Omega} (or greater) to about ${10}^{4}$ \ensuremath{\Omega} at 0.33 Mbar. Further studies using a second method reveal that the resistivity has dropped to below ${10}^{\ensuremath{-}1}$ \ensuremath{\Omega} cm and possibly much lower.