Panelists: Chris Benmore (co-Chair) Howard Sheng (co-Chair) Eric Chisolm Malcom Guthrie

1. HPCAT: Looking Forward Liquids and Amorphous Materials • Panelists: Chris Benmore (co-Chair) Howard Sheng (co-Chair) Eric Chisolm Malcom Guthrie Magnus Lipp Changyong Park Chris Tulk

2. HPCAT: Looking Forward Science Case PRD1: Transitions in liquids PRD2: Structure PRD3: Dynamics PRD4: Properties ?

3. Liquid-liquid phase transition?

5. Structure of dense hydrous silicate melts at pressures within the Earth’s mantle is unknown. • Structure-viscosity relations. • Rare liquid-liquid structural and electronic transitions at extreme conditions. Complexity and accuracy in non-crystalline structures - The frontier for non-crystalline x-ray diffraction is quantitative measurement of complex* structures (*beyond elements, binary alloys and simple molecular systems). HPCAT: Looking Forward Maximising Q-range is critical • Develop hydrothermal type cell for low P (1 GPa) and (800 deg. C). • High energy scattering DAC for very high pressures (110 GPa and 100K) to measure wide Q-range. • Background issues and data reduction methodology. X-ray GeO2 courtesy C.J. Benmore. Neutron GeO2 from ISIS database of neutron diffraction data (http://www.isis.stfc.ac.uk/groups/disordered-materials/database/database-of-neutron-diffraction-data6204.html)

6. HPCAT: Looking Forward The partial structure factor and radial distribution function SiO2 glass Can we do this at pressure? Anomalous x-ray scattering near absorption edge, problems with energies used, limited q range 2) Combining x-ray and neutron structure factor measurements, problems getting both datasets under identical conditions 3) Incorporation of computational modeling and theory

7. Liquid Dynamics Nature 410, 259 (2001) • IXS measurements of S(q,ω) allow the determination of non-ergodicity factorand kinetic fragility index. Science 302, 849 (2003) HPCAT: Looking Forward • Using high-P to tune atomic packing in glasses/supercooledliquids (and collective dynamics, i.e., fragility) • Observe strong-to-fragile glass transitions • Observe change in dynamics of liquid over triple points Points = Vibrational theory Circles = MD Triangles = Data

8. S(q,w) across phase changes • Observe S(q,w) at T above and below solid-solid-liquid triple point over a range of P • How does liquid S(q,w) change over triple point? HPCAT: Looking Forward Scan solid across phase change Scan liquid over triple point Scientific value Technical challenges • We expect electronic structure of liquid to adjust in response to nearest solid, but we don’t know how • Liquid behavior on melt (slope of melt line) depends on relative solid and liquid properties • How to extract material properties like vibrational spectrum g(w) from S(q,w) is unclear

9. Property measurements in liquids and amorphous solids Sakamaki et al (2012) HPCAT: Looking Forward Properties • Viscosity • Density • Ultrasonic velocity • EOS • Structural evolution with pressure of polymerized silicate liquids directly comparable to that in the viscosity (T.Sakamaki et al, JAP 2012)

10. HPCAT: Looking Forward Viscosity measurement under high pressure Simultaneous measurements of viscosity and structure

11. HPCAT: Looking Forward Current and Future Capabilities at HPCAT • X-ray diffraction/scattering for structure factor measurement • Laser heating • Whitebeamradiography volumetry • Ultrasonic velocity • Falling sphere viscometry • Portable PE press (VX-5 model) • Transmission densitometry • Liquid/amorphous structure measurement toward higher Q • Anomalous X-ray scattering • Synergy with neutron scattering • Collaboration with theory and computation • Liquid dynamics • Custom WC and diamond anvil design • New heater materials • Sintered diamond anvil (PEC)