High Pressure Techniques - Neutron Sciences at Oak Ridge 高压技术-中子科学在橡树岭.pdf

High Pressure Techniques M. Guthrie, Geophysical Laboratory - ENERGY FRONTIER RESEARCH IN EXTREME ENVIRONMENTS Extreme Conditions? Can mean harsh chemical or radiation environments, ultra high magnetic, electric or strain fields. Here, we’ll focus on very high pressures SI unit for pressure: Pascal, Pa ( 1 Nm-2 ) i.e. Force/Area Research at neutron and x-ray facilities is routinely conducted at pressures measured in GigaPascals, GPa*. Reference Atmospheric pressure ~ 0.0001 GPa Deepest point of the ocean ~ 0.1 GPa Stability field of diamond 5 GPa Center of the Earth: ~350 GPa (*I may slip into kbar = 1000 bar during talk…conversion is easy 1 GPa = 10 kbar) High pressure – a route to new materials Pressure can radically change material properties Phase diagram of ice [1] At higher pressure X still, ice X Polymorphism of Carbon forms Transparent sodium [2] Polymorphism in ice [2] Ma et al Nature 458 182 (2009). [1] P Pruzan, Private Comm. High pressure – a route to ne