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001     911410
005     20240709081948.0
037 _ _ |a FZJ-2022-04693
041 _ _ |a English
100 1 _ |a Alekseev, Evgeny
|0 P:(DE-Juel1)144426
|b 0
|e Corresponding author
111 2 _ |a Carnival Conference Session-2022
|g CCS2022
|c Cologne
|d 2022-06-08 - 2022-06-08
|w Germany
245 _ _ |a Chemical and structural evolution of simple and complex Th and U phases under high-pressure/high-temperature conditions
260 _ _ |c 2022
336 7 _ |a Conference Paper
|0 33
|2 EndNote
336 7 _ |a Other
|2 DataCite
336 7 _ |a INPROCEEDINGS
|2 BibTeX
336 7 _ |a conferenceObject
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336 7 _ |a LECTURE_SPEECH
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336 7 _ |a Conference Presentation
|b conf
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|0 PUB:(DE-HGF)6
|s 1668589423_27456
|2 PUB:(DE-HGF)
|x Invited
520 _ _ |a Th and U are early actinides with fascinating and very complex chemistry. Th is usually keeps 4+ oxidation state, but uranium belongs to the most complex chemical elements due to the owing 5f electrons. It is showing five oxidation states and very diverse coordination environment in solid state materials. Due to its extreme technological and natural impact, uranium chemistry has been extensively studied in last several decades. This talk will be focused on U and Th inorganic phases that forms under extreme conditions of HP (high pressure) and HT (high temperature). The effects of pressure on structural formation of some Th phases will be discussed. More complex is a behavior of uranium under extreme condition because it is accomplished with oxidation state change and formation of exotic materials. For example formation of the stable HP-modification of U2O5 which usually quite unstable under normal conditions. The structure of HP-U2O5 is strongly related to the fluorite–type UO2 (see Figure 1). That is in strong contrast to the structure of the normal pressure phase which is more related to the U(VI) phases. Using crystallographic data for HP-U2O5 modification as a reference, a DFT study of phase transition in pentavalent uranium oxide has been made and delivered the accurate force field parameters for U(V) in oxygen-bearing systems. In the systems with U(VI), the so called uranyl groups (UO22+) are forming. This group under normal conditions has a close to linear O=U=O (178°) geometry. We found that pressure can stabilize a strong bending of uranyl group within oxo-salt phases. It is due to the creation of steric effects which were not observed under normal conditions. For example, in the HP- Na4[(UO2)(SO4)3], uranyl group is bended up to 165.6(12)°. DFT modelling confirmed that such configuration is to be the most stable under high pressure.
536 _ _ |a 1232 - Power-based Fuels and Chemicals (POF4-123)
|0 G:(DE-HGF)POF4-1232
|c POF4-123
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650 2 7 |a Chemistry
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650 1 7 |a Energy
|0 V:(DE-MLZ)GC-110
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909 C O |o oai:juser.fz-juelich.de:911410
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910 1 _ |a Forschungszentrum Jülich
|0 I:(DE-588b)5008462-8
|k FZJ
|b 0
|6 P:(DE-Juel1)144426
913 1 _ |a DE-HGF
|b Forschungsbereich Energie
|l Materialien und Technologien für die Energiewende (MTET)
|1 G:(DE-HGF)POF4-120
|0 G:(DE-HGF)POF4-123
|3 G:(DE-HGF)POF4
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|v Chemische Energieträger
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914 1 _ |y 2022
920 _ _ |l yes
920 1 _ |0 I:(DE-Juel1)IEK-9-20110218
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|l Grundlagen der Elektrochemie
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980 _ _ |a conf
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980 _ _ |a I:(DE-Juel1)IEK-9-20110218
980 _ _ |a UNRESTRICTED
981 _ _ |a I:(DE-Juel1)IET-1-20110218

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