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TRANSCRIPT
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phase diagram for carbon dioxide
triple point: solid, liquid and gas
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phase diagram for carbon dioxide
source: NIST fluid data
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Phase Diagram of CO2 to High Pressure
x-ray diffraction through diamond anvil
source: Choong-Shik Yoo, PCCP, 2013, 15, 7949.
polymeric
?
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Phases I, II, and III of CO2
source: Yanqiang Han, et al., npj Quantum Materials, 2019, 4:10, 1-7.
structures fromquantum-mechanical perturbation theory (MP2)
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Phases I, II, and III of CO2
source: Yanqiang Han, et al., npj Quantum Materials, 2019, 4:10, 1-7.
II and III I and III
P(GPa) T(K) P(GPa) T(K)
12 524 13.8 98
13 531 13.4 198
14 543 12.6 298
15 554 11.6 398 6 / 11
Phases I, II, and III of CO2
source: Yanqiang Han, et al., npj Quantum Materials, 2019, 4:10, 1-7.
Han's new points are inred andblue.Main conclusion:There is a phase II-III boundary.
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3He and 4He phase diagrams
source: Aalto University School of Science, Finland http://ltl.tkk.fi/research/theory/helium.html
helium-4nuclear spin = 0abundance 99.9998%
helium-3nuclear spin = ½
1 M
Pa =
10
bar
I
II
λ line standardboiling
point
solid has higher
entropy
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diamond-anvil cell
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metallic hydrogen observed?
source: Robert Service, "Metallic hydrogen created in diamond vise," Science, 355(6323), 332-333, 27 January 2017.
Experiments by Isaac Silvera and Ranga Dias at Harvard. Hydrogen became "shiny and reddish." Metallic character identified by Raman scattering. As of 2018 Silvera and Dias stand by their conclusions.
Neil Ashcroft: "very convincing"Eugene Gregoryanz, "the word garbage cannot really describe it."
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metallic hydrogen observed?
T = 5K
source: Ranga Dias and Isaac Silvera, "Observation of the Wigner-Huntington transition to metallic hydrogen," Science, 355(6326), 715-718, 2017.