Compression behavior of Sm2Ti2O7-pyrochlore up to 50 GPa: single-crystal X-ray diffraction and density functional theory calculations

Abstract

Single-crystal X-ray diffraction at pressures up to 50 GPa has been employed to study the compression behavior of Sm 2 Ti 2 O 7 -pyrochlore. In contrast to earlier reports, we observed no pressure-induced amorphization or pressure-induced anion disorder up to 50 GPa. The experimental study has been complemented by density functional theory-based calculations. A combination of the theoretical and experimental data yields a bulk modulus of %185 GPa, significantly higher than a value which had been reported earlier. In comparison to earlier work, the current study provides more reliable data due to the use of neon as a pressure medium, which provides a more hydrostatic pressure than the aluminum, which had been employed as a pressure medium in the earlier studies. An analysis of the compressibility of Al 2 B 2 O 7 pyrochlores shows an approximately linear dependence of the bulk modulus on the unit cell volume.

Pressure-induced order–disorder transition in Gd 1.5 Ce 0.5 Ti 2 O 7 pyrochlore

“…The cationic radii are from Shannon, 1976 [25]. # is from the single crystal high-pressure XRD [26]. * is from the present study.…”

Molecular dynamics simulation of the structural, elastic, and thermal properties of pyrochlores

“…A detailed comparison between our results and DFT predictions [40][41][42][43][44] as well as available experimental data [45][46][47][48] is listed in Table 2. It can be seen that our calculated results are generally in good agreement with experimental measurements (noted Exp.…”

Structural Stability and Anharmonicity of Pr2Ti2O7: Raman Spectroscopic and XRD Studies

“…This was followed by one more high-pressure XRD study on Tb 2 Ti 2 O 7 that reported structural transition to monoclinic phase at 39 GPa . High-pressure Raman and XRD investigation of Sm 2 Ti 2 O 7 shows anionic disorder around 40 GPa, but recent high-pressure single-crystal study and density functional theory calculations did not support this finding of Sm 2 Ti 2 O 7 . Similarly Raman and XRD studies on Yb 2 Ti 2 O 7 have revealed a reversible structural transition to monoclinic phase at 28.6 GPa .…”

“…12 High-pressure Raman and XRD investigation of Sm 2 Ti 2 O 7 shows anionic disorder around 40 GPa, 8 but recent high-pressure single-crystal study and density functional theory calculations did not support this finding of Sm 2 Ti 2 O 7 . 13 Similarly Raman and XRD studies on Yb 2 Ti 2 O 7 have revealed a reversible structural transition to monoclinic phase at 28.6 GPa. 10 XRD studies at high pressures on Ho 2 Ti 2 O 7 and Y 2 Ti 2 O 7 have indicated structural transition to monoclinic phase at 37 and 42 GPa, respectively.…”