Axial Pressure Distribution in Solidified Argon and Methane

摘要

High‐pressure experiments at 77°K indicate an axial pressure distribution in solid argon and methane for pressures in the range of 2.0–9.0 kbar. The normalized resistivities of a separated pair of bismuth crystals were measured as a function of pressure in a piston‐in‐cylinder apparatus using these solidified gases as the pressure transmitters. At an applied pressure of 8.0 kbar, average pressure gradients of 1.3 kbar per cm and 1.1 kbar per cm were measured for initial compressions of argon and methane respectively. Subsequent second and third compressions of these solids to 8.0 kbar reduced the average pressure gradient to 0.8 kbar per cm for both materials. The gradients in each solid were found to depend primarily on the applied pressure, and the increase of shear strength with pressure. Shear strength parameters were determined for each solid from an analysis of second and third compression data. The increase of shear strength with pressure was within 5% of that determined for argon of similar purity obtained by independent extrusion techniques, but was high when compared to methane of considerably higher purity.