Abstract:The equation of state (EOS) of Cr3C2 at high pressure is studied by the synchrotron radiation x-ray diffraction (XRD) in a diamond anvil cell (DAC) at ambient temperature, and density functional theory (DFT). The XRD analysis shows that the orthorhombic structure is maintained to a maximum pressure of 44.5 GPa. The XRD data show that the bulk modulus is K
0 = 292 (18) GPa with
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“…Furthermore, the obtained data did not show any distortion of the bcc structure of Cr or any evidence of the occurrence of any chemical reactions leading to the formation of oxides or carbides e.g. Cr C 42 or Cr O 43 . Figure 1 ( a ) Integrated XRD patterns at different T around 30 GPa and ( b ) corresponding zoomed region around the XRD diffuse signal.…”
The high-pressure and high-temperature phase diagram of chromium has been investigated both experimentally (in situ), using a laser-heated diamond-anvil cell technique coupled with synchrotron powder X-ray diffraction, and theoretically, using ab initio density-functional theory simulations. In the pressure–temperature range covered experimentally (up to 90 GPa and 4500 K, respectively) only the solid body-centred-cubic and liquid phases of chromium have been observed. Experiments and computer calculations give melting curves in agreement with each other that can both be described by the Simon–Glatzel equation $$T_{m}(P) = 2136K (1 + P/25.9)^{0.41}$$
T
m
(
P
)
=
2136
K
(
1
+
P
/
25.9
)
0.41
. In addition, a quasi-hydrostatic equation of state at ambient temperature has been experimentally characterized up to 131 GPa and compared with the present simulations. Both methods give very similar third-order Birch–Murnaghan equations of state with bulk moduli of 182–185 GPa and respective pressure derivatives of 4.74–5.15. According to the present calculations, the obtained melting curve and equation of state are valid up to at least 815 GPa, at which pressure the melting temperature is 9310 K. Finally, from the obtained results, it was possible to determine a thermal equation of state of chromium valid up to 65 GPa and 2100 K.
“…Furthermore, the obtained data did not show any distortion of the bcc structure of Cr or any evidence of the occurrence of any chemical reactions leading to the formation of oxides or carbides e.g. Cr C 42 or Cr O 43 . Figure 1 ( a ) Integrated XRD patterns at different T around 30 GPa and ( b ) corresponding zoomed region around the XRD diffuse signal.…”
The high-pressure and high-temperature phase diagram of chromium has been investigated both experimentally (in situ), using a laser-heated diamond-anvil cell technique coupled with synchrotron powder X-ray diffraction, and theoretically, using ab initio density-functional theory simulations. In the pressure–temperature range covered experimentally (up to 90 GPa and 4500 K, respectively) only the solid body-centred-cubic and liquid phases of chromium have been observed. Experiments and computer calculations give melting curves in agreement with each other that can both be described by the Simon–Glatzel equation $$T_{m}(P) = 2136K (1 + P/25.9)^{0.41}$$
T
m
(
P
)
=
2136
K
(
1
+
P
/
25.9
)
0.41
. In addition, a quasi-hydrostatic equation of state at ambient temperature has been experimentally characterized up to 131 GPa and compared with the present simulations. Both methods give very similar third-order Birch–Murnaghan equations of state with bulk moduli of 182–185 GPa and respective pressure derivatives of 4.74–5.15. According to the present calculations, the obtained melting curve and equation of state are valid up to at least 815 GPa, at which pressure the melting temperature is 9310 K. Finally, from the obtained results, it was possible to determine a thermal equation of state of chromium valid up to 65 GPa and 2100 K.
“…Furthermore, the obtained data did not show any distortion of the bcc structure of Cr or evidence of the occurrence of any chemical reactions leading to the formation of oxides or carbides e.g. Cr 3 C 2 40 or Cr 2 O 3 . 41 During each experimental ramp, it was possible to study the textural evolution of the sample (and the insulating material) as a function of P-T .…”
The high-pressure and high-temperature melting curve of chromium has been investigated both experimentally (in situ), using a laser-heated diamond-anvil cell technique coupled with synchrotron powder X-ray diffraction, and theoretically, using ab initio density-functional theory simulations. In the pressure–temperature range covered experimentally (up to 90 GPa and 4500 K, respectively) only the solid body-centred-cubic and liquid phases of chromium have been observed. Experiments and computer calculations give melting curves in agreement with each other, that can be described by a Simon–Glatzel equation Tm(P) = 2136K(1+P/25.9) 0.41. In addition, a quasi-hydrostatic equation of state at ambient temperature has been experimentally characterized up to 131 GPa and compared with the present simulations. Both methods give very similar third-order Birch-Murnaghan equations of state with a bulk modulus of 182-185 GPa and its pressure derivative of 4.74-5.15. According to the present calculations, the obtained melting curve and equation of state are valid at least up to 815 GPa, being the melting temperature at this pressure 9310 K. Finally, from the obtained results, it was possible to determine a thermal equation of state of chromium valid up to 65 GPa and 2100 K.
“…There was no new peak appearance, which meant that transstilbene crystal did not experience a phase transition during the whole compression up to 16.0 GPa. [33,34] Moreover, upon pressure released, the position of diffraction peaks unchanged. But the diffraction peaks were broadening and the intensity showed a slight reduction, which was attributed to the decrease of crystallinity after compression.…”
Mechanoresponsive luminescent (MRL) materials have drawn extensive concern due to their potential applications in mechanical sensors, memory chips, and security inks; especially these possessing high emission efficiency. In this work, we found trans-stilbene crystal exhibited two different pressure-induced emission enhancement (PIEE) behaviors at different pressure areas. The structural characterizations combined with density functional theory calculation indicate that the first emission enhancement was due to the decrease of nonradiation transition by the weaken of energy exchange process between atoms and lattice. And the second emission enhancement was attributed to the strengthen of C–H…C interactions from the non-planarization comformation. The results regarding the mechanoresponsive behavior of trans-stilbene offered a deep insight into PIEE from the structural point of view, which will facilitate the design of and search for high-performance MRL materials.
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