December 5, 2016 04:05 PM

Strong parallels exist between the packing of tetrahedra and network topologies found in H2O and SiO2 phases. For examples, tridymite and cristobalite are analogues of ice Ih and Ic, respectively; low-energy hypothetical ice analogues of quartz have been predicted theoretically. By loading binary H2 + H2O samples in diamond anvil cells, a team used HPCAT facility and discovered a unique hydrogen-filled, ice-based chiral structure with oxygen topology very similar to the mineral quartz and other, as-of-yet-hypothetical, three-dimensional nets.  More...

December 2, 2016 12:43 PM

Thermoelectric materials have a wide range of applications, such as commercial refrigeration, energy-efficient engines, etc.  Their effectiveness has certain limitations, however, expressed by a dimensionless figure of merit, ZT = (α2σ/κ)T, where α is the Seebeck coefficient, σ the electrical conductivity, κ the thermal conductivity, and T the temperature. To obtain insight into the effects of structure and phase variation on the figure of merit, a technique for in-situ high-pressure thermoelectricity measurement has been developed at the HPCAT by utilizing a Paris-Edinburgh press.  More....

December 2, 2016 12:59 PM

Among thousands of known chemical interactions between common elements in the periodic table, there remain bonds that are curiously absent. Iron-bismuth is such a system, exhibiting complete immiscibility even in the liquid state. Using laser-heated diamond anvil cells, recent experiments at HPCAT have revealed a new form of intermetallic FeBi2More...

September 22, 2016 11:44 AM

A phase transition with an abrupt volume collapse of >20% could be associated with dramatic changes of electronic orbitals and/or spin-states of involved transition metals. Using HPCAT capabilities of high-pressure X-ray diffraction and X-ray emission spectroscopy, the mechanism of the pressure-driven lattice collapse in MnS and MnSe is studied. More...

September 9, 2016 02:03 PM

Electronic topological transition (ETT), where new features occur in the topology of the Fermi surface, has strong influences on structural, mechanical, and electronic properties of materials. Recent nuclear resonant inelastic x-ray scattering experiments at HPCAT strongly support a thermally driven ETT that drives anomalous changes in phonon dynamics.  More...