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Extreme P-T Devices

Extreme P-T devices (R. Boehler)

Tungsten hydride under pressure

Tungsten gaskets surrounding hydrogen in diamond anvil cells were observed to react with hydrogen under pressure to form WHn compounds. Cornell and Geophysical Laboratory scientists employed density functional theory (DFT) to map out possible stable structures with different n-values (n=1-6 and 8) followed by additional experiments to validate results of the calculations. No hydride is stable at ambient pressure.

Hydrogen at High P-T Conditions

Study of the phase diagram of hydrogen above one megabar using modified anvil designs with enhanced chemical resistance (with C.S. Zha). An Excimer laser is used to cut dishes into the culets of the diamond anvils, which will then partly be filled with a material that reduces the chemical/physical interaction between hydrogen and diamond.

 

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Extreme P-T Devices

The development of novel instruments is key for the planned research at extreme pressure and temperature conditions at the EFree Center. New diamond pressure cells will expand existing experimental capabilties in the areas of neutron diffraction, synchrotron X-ray measurements, Brillouin spectroscopy, and melting using laser-heating. A challenging task for neutron diffraction to study hydrogen-dominated liquids at megabar pressures and Brillouin spectroscopy for improved melting studies is a significant increase in the sample size.

 

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