Density measurements and structural properties of liquid and amorphous metals under high pressure

Abstract

International audienceWe have implemented an in situ X-ray diffraction analysis method suitable for the determination of pressure-volume-temperature equations of state in the critical case of liquid and amorphous materials over an extended thermodynamic range (T > 2000K and P > 40 GPa). This method is versatile, it can be applied to data obtained using various angle-dispersive X-ray diffraction high pressure apparatus and, contrary to in situ X-ray absorption techniques, is independent from the sample geometry. Further advantage is the fast data acquisition (between 10 and 300 s integration time). Information on macroscopic bulk properties (density) and local atomic arrangement (pair distribution function g(r)) can be gathered in parallel. To illustrate the method, we present studies on liquid Fe-S alloys in the Paris Edinburgh press and in laser-heated diamond anvil cell (DAC), and measurements on Ce glass in DAC at room temperatur

Structure and Density of Fe‐C Liquid Alloys Under High Pressure

“…Calculated atomic density as a function of the minimal distance r min for Fe‐C liquid alloy measured in a LH‐DAC experiment. The error bar at each point is related to the figure of merit χ 2 determining the validity of the density calculation (see Morard, Garbarino, et al, () for more details). The local minimum for χ 2 (minimum in the error bars) at 0.163 nm gives us the density for the studied liquid.…”

Polyamorphism of a Ce-based bulk metallic glass by high-pressure and high-temperature density measurements

“…In this work, we present a comprehensive experimental study of Ce 69 Al 10 Cu 20 Co 1 bulk MG by means of angle dispersive x-ray diffraction performed up to 16 GPa along two distinct isotherms (300 and 340 K). The whole diffuse signals have been here processed following the procedure as detailed in the Appendix, devised by [20][21][22] and later by Morard et al [23]. In this way, we have been able to extract directly the structure factor S(Q), the pair distribution g(r), the atomic density ρ and the compressibility as a function of pressure and temperature.…”

Dynamic X-ray diffraction observation of shocked solid iron up to 170 GPa

“…In addition to the study of the solid−solid phase transitions, like bcc−face-centered cubic (fcc) in temperature and bcc−hcp in pressure, and to the measurement of some properties of these phases (11,22,23), X-ray diffraction also allows the study of solid−liquid transitions (24) and measurement of liquid density (25). Static compression measurements of the melting curve of iron have led to over 1,000 K difference in melting temperatures between different studies (1,2,4,26,27).…”