Apparatus for X-Ray Measurements at Very High Pressure

Abstract

An apparatus has been developed which permits x-ray powder patterns to be obtained to over 500 kilobars presure. The apparatus is derived in part from the supported tapered piston electrical resistance apparatus in use in this laboratory, but the x rays are transmitted through a thin layer of LiH with suitable platinum collimation. The pressures are established by measuring the change of lattice parameter of a suitable marker mixed with the sample. These changes are then compared with volume changes obtained in shock wave work. Usual markers used to date include silver, rhodium, and palladium. Typical data for sample pressure versus average applied pressure for these metals are given. Also included is the change in lattice parameter with pressure for CsCl to 500 kilobars. The results are compared with the extrapolation of Bridgman's data.

Nuclear Magnetic Resonance ofGd155andGd157in the Cubic Ferromag

“…It would be most useful to have x-ray measurements of the structure of the high-pressure phases. Room-temperature measurements on cesium in our high-pressure x-ray apparatus 10 have not proved feasible. Efforts are being made to extend the high-pressure x-ray technique to low temperature where cesium gives much better x-ray patterns.…”

New Developments in Deformation Experiments at High Pressure

“…13). The gasket provides an extra support for the anvils and, as a result, this apparatus yields significantly higher pressures than does a Bridgman apparatus without a gasket (Perez-Albuerne et al 1964;Prins 1984). Because much of the force is supported by the gasket and the sample itself, the cylinder does not support a large load.…”

High Pressure

“…1 per cent. Drickamer and his colleagues (29) have extended the pressure range for X-ray diffraction to about 500 kb by adapting their opposed-anvil apparatus with support on the tapered faces, and Owen & Martin (30) have claimed similar pressures are obtainable with opposed dia mond anvils. Drickamer's apparatus has also been adapted for the Moss bauer effect (31) and for nuclear magnetic resonance (32).…”