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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.