Some high-pressure X-ray diffraction studies using beryllium gasketing on a diffractometer with rotating anode X-ray source

Abstract

The beryllium gasketing technique is employed in a high-pressure (0-10 GPa) x-ray powder diffractometer using a NaI(T1) scintillation detector in conjunction with a high-brilliance rotating anode x-ray source. The beryllium gasket permits the use of a liquid pressure transmitting medium in the sample chamber giving rise to hydrostatic pressure conditions. This metal gasket also allows the use of softer Cu K_α radiation because of less absorption, thereby ensuring high resolution. The Be gasket is calibrated using sodium chloride and the equation of state (EOS) of strontium metal is measured up to 6 GPa using Cu K_α radiation in both the low-pressure (fcc) and high-pressure (bcc) phases. However, for high-Z samples like rare earths, Mo K_α radiation is employed to minimize absorption in the sample material. The high-pressure valence transition and the EOS of the rare earth alloy Ce_0.92 La_0.08 were studied up to 5.5 GPa. The γ→α transition in this cerium alloy is smeared out as compared to pure cerium metal.