Re-appearance of superconductivity under high pressure
February 23, 2012 01:25 PM

In the superconducting iron chalcogenides, a second superconducting phase suddenly reemerges above 11.5 GPa, after the Tc drops from the first maximum of 32K at 1 GPa. The Tc of the re-emerging superconducting phase is higher than the first maximum, reaching 48.0–48.7K for two materials studies. (more…) (Figure: Pressure dependence of the superconducting temperature)

A miniature X-ray emission spectrometer (miniXES) for high-pressure studies in a diamond anvil cell
February 17, 2012 12:57 PM

A miniature X-ray emission spectrometer has been successfully commissioned by a team of researchers from the University of Washington, LLNL and HPCAT. (more)
 (Photograph of the miniXES spectrometer at 16ID-D with DAC and Pilatus in place)

 

A new capability at HPCAT for viscosity measurement at high pressures
February 14, 2012 11:29 AM

White x-ray radiography measurement combined with Paris-Edinburgh cell at the HPCAT beamline 16BM-B provides a capability of investigating viscosity of liquid at high pressure and high temperature conoditions using falling sphere viscometer technique.  A preliminary experiment was carried out for a silicate melt at 3.5 GPa and 1600 °C.  Pt sphere smoothly fell in the silicate melt. Viscosity can be obtained by deriving the falling velocity of the Pt sphere. Video

Electronic dynamics and plasmons of sodium under compression
January 24, 2012 11:31 AM

Sodium displays a great deal of surprising behaviors under high pressure such as melting at room temperature at 118GPa and transition to an insulator over 200GPa. Recent HPCAT experiments measured plasmon excitations of sodium from ambient pressure up to 97GPa using the momentum-dependent inelastic X-ray scattering technique. (more)

In-situ gas loading in a DAC via x-ray induced chemistry
November 8, 2011 02:26 PM

A novel method to load oxygen in a sealed diamond anvil cell, via the x-ray induced decomposition of potassium chlorate (KClO3) is demonstrated. It is anticipated that this technique will be useful in loading even more challenging, difficult-to-load gases such as hydrogen and also to load multiple gases. (more) (The photo shows a sample of KC1O3  powder inside a diamond anvil cell with reddish damage spots [near the center] of molecular oxygen after x-ray bombardment at 15 GPa. The clear bubbles are ruby spheres.)

Hard as Diamond: A New Form of Carbon Created under Ultrahigh Pressure
November 4, 2011 12:14 PM

HPCAT experiments showed that at pressures above 40 GPa, the arrangement of the bonds between the carbon atoms in the glassy spheres had completely shifted to a form that endowed the spheres with diamond-like strength. (more)

Evidence of superdense aluminium
November 4, 2011 02:39 PM

Scientists study the behavior of materials under conditions simulating those in the core of the Earth. Here we report the synthesis of a superdense stable phase--a new phase--of body-centred-cubic aluminium (bcc-Al). The phase occurred under non-equilibrium conditions of an ultrafast laser-induced microexplosion inside a sapphire (α-Al2O3) crystal. (more)