A pressure calibration method for a portable wide-access “panoramic” cell

Abstract

A simple and convenient pressure calibration method is developed for a newly designed portable wide-access 'panoramic' cell. This cell is adapted to angle-dispersive-mode high-pressure in situ neutron diffraction of reactor neutron sources. This pressure calibration method has established a relationship between the cell pressure and the anvil displacement (gasket compression) based on the fixed-point calibration technique. By employing TiZr gasket with a thickness of 3 mm and WC anvil with a culet of 4 mm diameter, the average anvil displacements are 1.31 mm and 2.22 mm for Bi phase transitions (2.55 GPa and 7.7 GPa), and 1.85 mm for Ba phase transitions (5.5 GPa), respectively. In this pressure range, the pressure increases quickly with decreasing gasket thickness, and undergoes a linear increase with the anvil displacement. By extrapolating the calibration curve, the cell pressure will achieve 10 GPa when the anvil displacement is around 2.5 mm.

Neutron Diffraction of Large-Volume Samples at High Pressure Using Compact Opposed-Anvil Cells

“…A detailed description of the high pressure press can be found elsewhere. [16,17] Pressure calibration experiments were conducted at room temperature. The phase transition of Bi (I-II transition at 2.55 GPa and III-V transition at 7.7 GPa) were used as fixed points to determine the generated pressures.…”