Titre :

The Chemistry, Recrystallization and Thermal Expansion of Brannerite from Akchatau, Kazakhstan

Auteur(s) :

Chen, Ruiqi [Auteur]
Unité de Catalyse et Chimie du Solide - UMR 8181 [UCCS]
St Petersburg State University [SPbU]
Siidra, Oleg I. [Auteur]
St Petersburg State University [SPbU]
Firsova, Vera A. [Auteur]
Arevalo-Lopez, Angel [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Colmont, Marie [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Ugolkov, Valery L. [Auteur]
Bocharov, Vladimir N. [Auteur]
St Petersburg State University [SPbU]

Titre de la revue :

Materials

Numéro :

16

Pagination :

1719

Éditeur :

MDPI

Date de publication :

2023-02-18

ISSN :

1996-1944

Mot(s)-clé(s) en anglais :

brannerite
metamict minerals
recrystallization of metamict minerals
thermal analysis
thermal expansion
radioactive minerals
matrix for HLW immobilization

Discipline(s) HAL :

Chimie/Chimie inorganique

Résumé en anglais : [en]

Numerous studies expose the potential of brannerite to become a good matrix, concentrating fission products and actinides. Minerals can complement the data collected from the synthetic materials and offer an advantage of ...
Lire la suite >Numerous studies expose the potential of brannerite to become a good matrix, concentrating fission products and actinides. Minerals can complement the data collected from the synthetic materials and offer an advantage of a long-time exposure to radiation. Natural metamict brannerite from Akchatau, Kazakhstan, and its annealed sample were studied by EPMA, Raman spectroscopy, TGA, DSC, XRD and HTXRD. The radioactivity of pristine and annealed samples of brannerite was measured. Brannerite from Akchatau is characterized by the absence of significant amounts of REE and yttrium. The studied brannerite regains its structure at a temperature ~650 °C, revealed by the HTXRD and DSC. HTXRD was also performed on the annealed recrystallized brannerite. The thermal expansion for brannerite has been determined for the first time. The brannerite structure expands anisotropically with temperature increase. All the thermal expansion coefficients are positive except for αβ. The decreasing beta parameter indicates a “shear structural deformation“. The angle between the 1st axis of the tensor and the crystallographic a axis decreases with the increase of the temperature. The structure expands mostly in the α11 direction, approaching the bisector of the β angle. Brannerite has a low CTE at room temperature—αv = 16 × 10−6 °C−1, which increases up to 39.4 × 10−6 °C−1 at 1100 °C. In general, the thermal stability of brannerite is comparable to that of the other perspective oxide radioactive waste-immobilizing matrices (e.g., Ln2Zr2O7, CePO4, CaTiO3, CaZrTi2O7). The calculated thermal expansion of brannerite and the understanding of its underlying crystal chemical mechanisms may contribute to the behavior prediction of the material (both metamict and crystalline) at high temperatures.Lire moins >

Langue :

Anglais

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

Université de Lille
CNRS
Centrale Lille
ENSCL
Univ. Artois

Collections :

• Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181

Équipe(s) de recherche :

Matériaux inorganiques, structures, systèmes et propriétés (MISSP)

Date de dépôt :

2023-05-30T15:07:08Z
2023-06-22T10:53:36Z