Pressure-induced phase transition, its mechanism and compressibility studies on nanocrystalline and bulk U3O8

High Pressure X-Ray Diffraction (HPXRD) studies were conducted on powder samples of U3O8 with crystallite sizes of 54 nm, 82 nm, as well as bulk U3O8. The investigation revealed that U3O8 undergoes a phase transition to a fluorite phase through an intermediate tetragonal structure, with the (200) pl...

Full description

Saved in:
Bibliographic Details
Published in:Journal of solid state chemistry 2023-12, Vol.328, p.124340, Article 124340
Main Authors: Shukla, Balmukund, Kumar, N.R. Sanjay, Maji, Dasarath, Chakraborty, Soumee, Upadhyay, Anuj, Srihari, V., Ravindran, T.R., Shekar, N.V. Chandra
Format: Article
Language:English
Subjects:
Actinide compounds
Bulk modulus
High pressure
Nano-materials
X-ray diffraction
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:High Pressure X-Ray Diffraction (HPXRD) studies were conducted on powder samples of U3O8 with crystallite sizes of 54 nm, 82 nm, as well as bulk U3O8. The investigation revealed that U3O8 undergoes a phase transition to a fluorite phase through an intermediate tetragonal structure, with the (200) plane of the orthorhombic structure playing a pivotal role. This transition occurs through the movement of uranium atoms while maintaining the overall integrity of the lattice. The phase transition is sluggish, and an extensive coexistence regime of the ambient and High-Pressure (HP) fluorite phase is observed in nano form as compared to bulk- U3O8. Moreover, the ambient phase of nano- U3O8 exhibits an elevated bulk modulus of 92 GPa, in contrast to the bulk sample's modulus of 78 GPa. Similarly, for the high-pressure phase, the bulk modulus is 419 GPa for nano- U3O8 and 367 GPa for bulk- U3O8. These findings provide valuable insights into the phase behavior and compressibility of U3O8, thereby carrying potential implications for nuclear technologists. •Nanocrystalline U3O8 exhibits enhanced compressibility and a significantly broader coexistence regime compared to the bulk sample.•We have established that the bulk modulus experiences an increase rate of 0.214 in response to the reduction in crystallite size.•Under high-pressure conditions, U3O8 undergoes a phase transition from an orthorhombic to a fluorite structure via a tetragonal phase.•The pressure-induced phase transition involves subtle displacements of U atoms while a significant portion of the lattice remains unchanged.
ISSN:0022-4596
1095-726X
DOI:10.1016/j.jssc.2023.124340