This title appears in the Scientific Report :
2016
Please use the identifier:
http://hdl.handle.net/2128/13474 in citations.
New insights into thorium and uranium oxo-arsenic (III/V) and oxo-phosphates (V) crystal chemistry
New insights into thorium and uranium oxo-arsenic (III/V) and oxo-phosphates (V) crystal chemistry
The fundamental chemistry of actinides is of great interest owing to the diverse number of valence states and complex coordination chemistry of the actinides. The phases based on actinides and oxo-salt fragments have been under thorough investigation in the last decades. These compounds can be widel...
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Personal Name(s): | Yu, Na (Corresponding author) |
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Contributing Institute: |
Nukleare Entsorgung; IEK-6 |
Imprint: |
2016
|
Physical Description: |
160 |
Dissertation Note: |
RWTH-Aachen, Diss., 2016 |
Document Type: |
Dissertation / PhD Thesis |
Research Program: |
Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) Helmholtz Young Investigators Group: Energy Nuclear Waste Management |
Subject (ZB): | |
Link: |
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Publikationsportal JuSER |
The fundamental chemistry of actinides is of great interest owing to the diverse number of valence states and complex coordination chemistry of the actinides. The phases based on actinides and oxo-salt fragments have been under thorough investigation in the last decades. These compounds can be widely found in nature and they affect the migration process of actinides in nature. A better understanding of the fundamental coordination chemistry of actinide compounds with oxo-salts of group V elements is not only important for understanding the actinides behavior within the migration process but can also be used to understand actinide properties in phosphate ceramics. Concerning the radioactive issues, the less radioactive early actinides (i.e. U, Th) can be taken as modeling elements to study the crystal chemistry of the transuranic elements (Np, Pu) without the major handling problems. This can be done as Th(IV) has a very similar coordination chemistry with An(IV) and U(VI) can be chosen as a modeling element for transuranic elements in higher valence states. Therefore, a systematic research on the actinides (U, Th) bearing phases with tetrahedral oxo-anions such as phosphates and arsenates have been performed in this work. High temperature (HT) solid state reaction, High pressure high temperature (HP-HT) solid state reaction and the hydrothermal method were the methods of choice for synthesizing actinide bearing oxo-arsenic(III/V) and oxo- phosphorus(V) phases in the past three years. As a result, numerous novel compounds containing actinides were obtained. The structures of all compounds were determined using single crystal X-ray diffraction data. Raman spectroscopy, EDS, DSC and high temperature powder X-ray diffraction (HT-PXRD) measurements were implemented to characterize the chemical and physical properties of the obtained compounds. The core of this dissertation is a fundamental study of the crystal chemistry of actinides (Th, U) oxo-arsenic (III/V) and oxo-phosphate(V) phases that were derived from the before mentioned methods. They can be separated into several main parts according to the structural features: layers in U(VI) phases (chapter 3); cations driving structural diversity of thorium arsenates and phosphates (chapter 4 and 5); uranium metaphosphate with (PO3)nn- polymeric chains (chapter 6); mixed-valent arsenic(III/V) Th compounds obtained under extreme pressure (chapter 7); series of compounds adopting the typical structure type of KTh2(AsO4)3 and presented by ATh2(AsO4)3(A= K, Rb, Cs, Ag), LiTh2(PO4)3 and BUIV2(PO4)3 (B= Rb, Cs); tri-phosphate and tri-arsenate T3O10 units in the ATh(T3O10) (A= Rb, Cs; T= P, As) family (chapter 7).DokumentartDissertation / PhD ThesisPublikationsformonlineSpracheEnglishExterne IdentnummernHBZ: HT018840921Interne IdentnummernRWTH-2015-07495Datensatz-ID:564812Beteiligte LänderGermany |