Amorphization of a proposed sorbent of strontium, brushite, CaHPO4•2H2O, studied by X-ray diffraction and Raman spectroscopy

We present a systematic study of the transformation of brushite (dicalcium phosphate dihydrate, CaHPO4•2H2O) under irradiation of electrons of well-defined energy (2.5 MeV) and flux as a function of the irradiation dose. Contrarily to model hydroxides such as portlandite and brucite, which are very...

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Bibliographic Details
Published in:Journal of nuclear materials 2021-03, Vol.545, p.152751, Article 152751
Main Authors: de Noirfontaine, Marie-Noëlle, Garcia-Caurel, Enrique, Funes-Hernando, Daniel, Courtial, Mireille, Tusseau-Nenez, Sandrine, Cavani, Olivier, Jdaini, Jihane, Cau-Dit-Coumes, Céline, Dunstetter, Frédéric, Gorse-Pomonti, Dominique
Format: Article
Language:English
Subjects:
Amorphization
Atomic structure
Beta rays
Brucite
Brushite
CaHPO4•2H2O
Calcium
Calcium phosphates
Calcium pyrophosphates
Chemical composition
Decomposition
Decontamination
Electron radiation
Emitters (electron)
Hydrogen bonding
Hydrogen bonds
Hydroxides
Irradiation
Magnesium hydroxide
Radiation
Radiation damage
Radiation dosage
Radiation tolerance
Raman spectroscopy
Sorbents
Spectroscopy
Spectrum analysis
Strontium
Transformations
Unit cell
X-ray diffraction
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Summary:We present a systematic study of the transformation of brushite (dicalcium phosphate dihydrate, CaHPO4•2H2O) under irradiation of electrons of well-defined energy (2.5 MeV) and flux as a function of the irradiation dose. Contrarily to model hydroxides such as portlandite and brucite, which are very resistant to electron radiation damage, the studied brushite decomposes quite easily, even for very low irradiation doses. Irradiated brushite samples were characterized using X-ray diffraction (XRD) and Raman spectroscopy to get complementary information about changes in atomic structure and chemical composition respectively under irradiation. XRD showed that irradiation causes a very limited dilatation of unit cell of crystalline brushite, which becomes progressively amorphous with increasing radiation dose. Raman spectroscopy complemented XRD results and confirmed that the transformation of brushite to the amorphous phase was not abrupt, but rather progressive. Raman spectroscopy allowed for the identification of the amorphous phase as a calcium pyrophosphate. Both techniques showed that the amorphization of brushite was not fully complete at the maximum dose used, 5.5 GGy (4 C). Interestingly, monetite phase, (CaHPO4 dicalcium phosphate), was not detected at any step of the transformation as it is the case when brushite is thermally decomposed. This study reveals the high sensitivity to electron radiation of both hydrogen bonds and protonated phosphate units in brushite, thus facilitating the transformation into pyrophosphate. The damage of brushite by energetic electrons is to be carefully considered for applications related to the use of brushite as ion-exchanger in the decontamination of effluents polluted with strontium-90, an efficient beta ray emitter.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2020.152751