X-ray diffraction measurements of cerium in the vicinity isostructural gamma-alpha transition have been performed with high precision and accuracy from room temperature to almost 800 K. The disputed location critical point has found occur at 1.5+/-0.1 GPa 480+/-10 data are well fit by Kondo volume collapse model plus a quasiharmonic representation phonons. resultant free energy is validated against for thermodynamic Grüneisen parameter and, beyond dominant spin-fluctuation contribution,...

We have developed a unique device, dynamic diamond anvil cell (dDAC), which repetitively applies time-dependent load/pressure profile to sample. This capability allows studies of the kinetics phase transitions and metastable phases at compression (strain) rates up 500 GPa/s (approximately 0.16 s(-1) for metal). Our approach adapts electromechanical piezoelectric actuators conventional design, enables precise specification control applied load/pressure. Existing DAC instrumentation...

Static compression experiments over 4 Mbar are rare, yet critical for developing accurate fundamental physics and chemistry models, relevant to a range of topics including modeling planetary interiors. Here we show that focused ion beam crafted toroidal single-crystal diamond anvils with ~9.0 μm culets capable producing pressures 5 Mbar. The surface prevents gasket outflow provides means stabilize the central culet. We have reached maximum pressure ~6.15 using Re as in situ marker, regime...

We have studied pressure-induced chemical reactions in carbon monoxide using both a diamond anvil cell and modified large volume press. Our spectroscopic data reveal that disproportionates into molecular CO2 solid lactone-type polymer; photochemically above 3.2 GPa, thermochemically 5 GPa at 300 K, or 3 ∼2000 K as achieved by laser heating. The product can be recovered ambient conditions with high degree of conversion, measured to up 95% the original CO. Its fundamental structure includes...

Direct laser heating of molecular ${\mathrm{N}}_{2}$ to above $1400\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ at $120--130\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ results in the formation a reddish amorphous phase and transparent crystalline solid $2000\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Raman x-ray data confirm that is cubic-gauche nitrogen (cg-N), while could be an extension already known $\ensuremath{\eta}$ phase. The color phase, however, might also indicate presence...

Recently, static pressures of more than 1.0 TPa have been reported, which raises the question: what is maximum pressure that can be achieved using diamond anvil cell techniques? Here we compile culet diameters, bevel angles, and reported from literature. We fit these data find an expression describes as a function diameter. An extrapolation our reveals diameter 1 μm should achieve ∼1.8 TPa. Additionally, for generation ∼400 GPa with single beveled anvil, most commonly parameters are ∼20 μm,...

High-pressure x-ray emission measurements are used to provide crucial evidence in the longstanding debate over nature of isostructural ($\ensuremath{\alpha}$, $\ensuremath{\gamma}$) volume collapse elemental cerium. Extended local atomic model calculations show that satellite $L\ensuremath{\gamma}$ line offers direct access total angular momentum observable $⟨{J}^{2}⟩$. This experiences a 30% steplike decrease across collapse, validating Kondo conjunction with previous measurements. Direct...

Abstract It is qualitatively well known that kinetics related to nucleation and growth can shift apparent phase boundaries from their equilibrium value. In this work, we have measured effect in Bi using time-resolved X-ray diffraction with unprecedented 0.25 ms time resolution, accurately determining transition pressures at compression rates spanning five orders of magnitude (10 –2 –10 3 GPa/s) the dynamic diamond anvil cell. An over-pressurization Bi-III/Bi-V boundary observed fast for...

Micro- and nanocrystalline systems exhibit properties that differ markedly from bulk systems. Diamond, a prototypical system, demonstrates broadening, shift, emergence of Raman phonon modes are believed to originate finite-size effects. Such information should be useful in constraining confinement models developed describe the state these mesoscopic For example, previous investigations have analyzed crystallite size stresses scientifically technologically relevant environments, including...

We report combined x-ray and Raman studies of beryllium in helium argon pressure media at pressures approaching 200 GPa. Our results are generally consistent with recent confirming the stability hexagonal close-packed phase to highest pressures. However, quasihydrostatic conditions our lead a stiffer equation state (${K}_{0}=109.88$, ${K}_{0}^{\ensuremath{'}}=3.59$) gradual approach toward more ideal $c∕a$ ratio 1.60 180 Combining data, we able evaluate dependence elastic shear modulus...

The high pressure melting curve of tin was measured to 45 GPa using a designer diamond anvil cell with an integrated internal resistive heating element. Melting the sample detected by abrupt increase in electrical resistance and also change slope power versus temperature curve. temperatures determined these two methods are good agreement each other. We find that tends monotonically increasing reaches about 2000 K at GPa.

We study the pressure evolution of 4$f$ electrons in elemental praseodymium metal compressed through several crystallographic phases, including large volume-collapse transition at 20 GPa. Using resonant x-ray emission, we directly and quantitatively measure development multiple electronic configurations with differing occupation numbers, key quantum observable related to delocalization strongly correlated electrons. These results provide a high-fidelity test prior predictions by dynamical...

Core–shell X-ray emission spectroscopy (XES) is a valuable complement to absorption (XAS) techniques. However, XES in the hard regime much less frequently employed than XAS, often as consequence of relative scarcity instrumentation having energy resolutions comparable with relevant core-hole lifetimes. To address this, family inexpensive and easily operated short-working-distance spectrometers has been developed. The use computer-aided design rapid prototype machining plastics allows...

The high-pressure behavior of $\mathrm{C}{\mathrm{e}}_{2}{\mathrm{O}}_{3}$ was studied using angle-dispersive x-ray diffraction to 70 GPa and compared with that $\mathrm{Ce}{\mathrm{O}}_{2}$. Up the highest pressure remains in hexagonal phase (space group 164, $P\overline{3}2/m1)$ typical for lanthanide sesquioxides. A theoretically predicted instability 30 is not observed. isothermal bulk modulus its derivative quasihydrostatic case are...

The behavior of the f-electrons in lanthanides and actinides governs important macroscopic properties but their pressure temperature dependence is not fully explored. Cerium with nominally just one 4f electron offers a case study its iso-structural volume collapse from γ-phase to α-phase ending critical point (p C, V T C), unique among elements, whose mechanism remains controversial. Here, we present longitudinal (c L) transverse sound speeds T) versus higher than room C for first time....

Laboratory hypervelocity impact experiments in which quartz was shock-loaded from 42 to 56 gigapascals imply that type A pseudotachylites form by strain heating and contribute the loss of strength rocks central uplift large structures. Shock impedance-matched aluminum sample containers, contrast steel produced nearly single-wave pressure loading, enhanced deformation, silicate samples. Strain may act with shock devolatilize planetary materials destroy extraterrestrial organic material an impact.

The longitudinal and transverse sound speeds, cL cT, of polycrystalline cerium were measured under pressure across the iso-structural γ–α phase transition at 0.75 GPa to beyond 3 GPa. In contrast previous methods all quantities directly obtained no assumptions made about size volume collapse. Up our values for are in excellent agreement with ones, while cT significantly lower. We deduce adiabatic bulk modulus BS, shear , dependent Debye temperature, ΘD(p). ΘD(p) is good recent results...

We measured the atomic volume of Ag in a toroidal diamond anvil cell to maximum pressure 416 GPa and calculated elastic constants up 750 460 GPa, respectively. Our density functional theory calculations at 0 K utilize an all-electron fully relativistic method agree well with our measurements, particularly pressures above ∼75 GPa. corrected experimental results for non-hydrostaticity using line shift analysis, resulting Vinet equation state (EOS) parameters are reported. find that uniaxial...

We report a joint experimental and theoretical study of the dynamical structural properties lead fluoride $({\mathrm{PbF}}_{2}).$ Specifically, we have performed detailed measurements room-temperature Raman-active phonon modes to 310 kbar. verify transition at about 4 kbar from cubic (\ensuremath{\beta}) orthorhombic (\ensuremath{\alpha}) phase recovery \ensuremath{\alpha} ambient conditions. At approximately 147 kbar, observe transformation modification that label \ensuremath{\gamma}. The...

We present an equation of state for the solid and liquid phases lithium fluoride that covers a wide range conditions from ambient pressure temperature to high pressures temperatures exhibited in shock- ramp-compression studies. The particular phase we have focused on this work is B1 phase. followed approach where heat-capacity functions both are fit experimental data our own quantum molecular dynamics simulations then integrated thermodynamically consistent way obtain corresponding...

Compression of PrN yields a phase transformation to tetragonal structure with ~8.8 % volume collapse at ~40 GPa ambient temperature. A refinement reveals distorted CsCl-like for the high pressure PrN(II), which is different from phases seen among other lanthanide monopnictides. The space group new P4/nmm (#129) Pr in 2c(0,1/2,0.3546) and N 2a(0,0,0) positions. PrN(II) persists 85 GPa.

This work is the first report of use nonlinear optics techniques to probe pressure dependence electronic energy levels in a solid. An advantage which may be significant that for multiphoton processes involved, relatively low-energy photons are not absorbed by cell windows can states having energies would strongly one-photon excitation. The measurements follow energetically lowest polariton KI using three-photon-spectroscopy method.

Using nonresonant Fe $K\ensuremath{\beta}$ x-ray emission spectroscopy, we reveal that Sr substitution into ${\mathrm{CaFe}}_{2}{\mathrm{As}}_{2}$ decouples the moment from volume collapse transition, yielding a collapsed-tetragonal, paramagnetic normal state out of which superconductivity develops. X-ray diffraction measurements implicate $c$-axis lattice parameter as controlling criterion for moment, promoting generic description appearance pressure-induced in alkaline-earth-based 122...