X-ray-diffraction study of the equation of state and the phase transition in cesium iodide at nearly hydrostatic pressure

Abstract

X-ray-diffraction study of CsI was performed along the room-temperature isotherm up to pressure of 52 CxPa by using a diamond-anvil cell and compressed helium as a pressure medium. It turned out that the equation-of-state data obtained differ from the results of previous nonhydrostatic measurements, with the latter overestimating the pressure. The phase diagram of CsI is found to be sensitive to the hydrostaticity of a pressure transmitting medium as well. The experimental data suggest that the cubic phase of CsI transforms directly into the orthorhombic one under hydrostatic conditions.

Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

“…In previous experiments on Y [10], no measureable difference was observed in the pressure dependence of T c with (dense He) or without pressure medium in the 35 -90 GPa pressure region where they could be compared. One should not forget, however, that in nonhydrostatic experiments employing no pressure medium, shear stress effects may have a significant influence on how T c changes under pressure [2,31,32].…”

Phonon softening and high-pressure low-symmetry phases of cesium iodide

“…Recent experiments [8,9] suggest that CsI undergoes a continuous transition from the cubic (82) to an hcp structure, passing through an orthorhombic phase, C2," which is, however, different from the previously proposed structure [2], Dzi, . In this paper we study the relative stability of various phases of CsI at high pressure (cubic, tetragonal, and the newly proposed orthorhombic structure).…”

“…[1,3] nor theoretical [4][5][6][7] work. In particular, though the cubic-to-tetragonal transition has been theoretically predicted by both semiempirical [4] and first-principles [5,6] calculations, no evidence of the further orthorhombic distortion has been found by either methods [7].Recent experiments [8,9] suggest that CsI undergoes a continuous transition from the cubic (82) to an hcp structure, passing through an orthorhombic phase, C2," which is, however, different from the previously proposed structure [2], Dzi, . In this paper we study the relative stability of various phases of CsI at high pressure (cubic, tetragonal, and the newly proposed orthorhombic structure).…”

Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays

“…The only experiment that may be classified into this category is the one by Aleksandrov et a/. [80]. If we assign the three observed peaks after the phase transition to be (020), (002), and (111) of the orthorhombic structure, the volume thus calculated shows no observable discontinuity from the lower pressure phase.…”

“…He pressure medium). The more recent study of Aleksandrov et al [80] where He was used as the pressure medium seems to best approximate a hydrostatic pressure environment under these pressures. No significant broadening is seen in the single crystal diffraction peaks up to the highest pressure studied (50 GPa).…”