High Pressure—High Temperature, X-Ray Diffraction Apparatus

Abstract

A tetrahedral-anvil press has been developed that permits x-ray diffraction powder measurements at pressures to 75 kb and temperatures to 1000°C. A counting technique, rather than photographic film, is used for x-ray detection. Sample tetrahedra of compressed LiH, boron, and boron-filled plastic are used in place of the pyrophyllite customarily used for this purpose. Two possible entrance pupils are used for the x-ray beam; (1) through an anvil face, and (2) through one of the compressible gaskets. Examples of the use of this versatile apparatus for determining crystal structures (KCl, Ba, and Sn), volume compressibility (Ba), lattice-parameter changes (BN), and phase diagrams (Sn) are given.