29 October 2017 to 3 November 2017
Australia/Sydney timezone

New aspects of U(V) chemistry in oxo-materials: from ambient to extreme conditions

1 Nov 2017, 16:15
Oral Presentation National and international collaborative waste management programs Ceramic and Glass-Ceramic Wasteforms


Prof. Evgeny Alekseev (Forschungszentrum Jülich)


Using extreme pressure (10GPa/1200°C) we obtained a new modification of U2O5 with an extraordinary dense structure. The crystal structure of resulting HP (high pressure)-U2O5 is dramatically differs from ambient pressure polymorph so called delta-U2O5. The structure of HP-U2O5 is more related to the cubic UO2 than to the layered delta-U2O5. Using state of the art ab initio methods we reveal the stability ranges of both ambient and high pressure forms of U2O5 and demonstrated a potential pathway of phase transition under pressure. In second case we demonstrated that the pentavalent uranium (U(V)) can be stabilized in [Ln(UVO2)W4O14] (Ln = Nd-Tm and Y) series via aliovalent substitution of Ca2+ cations. We confirmed U(V) stabilization using state of the art methods such as U M4 edge high energy resolution X-ray absorption near edge structure (HR-XANES).Magnetic study reveals low temperature ordering of 5f1 and 4fn systems. All the phases tend to demonstrate the antiferromagnetic properties with significant difference between pure 5f1 system (Y-beating phase) and 5f1-4fn compounds (Nd-Tm).

Primary author

Prof. Evgeny Alekseev (Forschungszentrum Jülich)

Presentation Materials

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