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Das P, Vats BG, Samui P, Rai AK, Yadav AK, Shafeeq M, Kesari S, Parida SC. Structure and Stability of Charge-Coupled Lanthanide-Substituted Ca 10(PO 4) 6F 2 as a Potential Fluoride Bearing Nuclear Waste Form. ACS OMEGA 2024; 9:35873-35887. [PMID: 39184507 PMCID: PMC11339994 DOI: 10.1021/acsomega.4c04809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/18/2024] [Accepted: 07/23/2024] [Indexed: 08/27/2024]
Abstract
The structure and stability of charge-coupled lanthanide-substituted Ca10(PO4)6F2 as a potential fluoride-bearing nuclear waste form for the back-end fuel cycle of Gen-IV molten salt reactor have been studied in detail. Here, calcium fluorapatite (CaFAp) as a model structure was taken for incorporation of trivalent lanthanides (Lns, La-Lu except Pm) in a charge-coupled fashion, i.e., 2Ca2+ = Na+ + Ln3+. In these fluorapatite phases, Na+ is substituted exclusively at nine coordinated sites, Ca1, while Ln3+ is preferentially substituted at seven coordinated sites, Ca2. These compositions are further characterized for the local structure by Fourier transform infrared (FTIR) and Raman spectroscopy. Thermal expansion was measured by high-temperature X-ray diffraction (XRD) and the instantaneous thermal expansion coefficient correlates well with the unsubstituted CaFAp. The heat capacities of these solids were measured by differential scanning calorimetry and drop calorimetry, whereas enthalpies of formation were obtained by high-temperature oxide melt solution calorimetry. The thermodynamic analysis demonstrated that lanthanides having ionic radii closure to Ca2+ (Sm3+ and Gd3+) imparted higher thermodynamic stability to the substituted CaFAp as compared to that of other Ln3+. According to structural and thermodynamic investigations, entropy-stabilized fluorapatite waste from NaPr0.125Nd0.125Sm0.125Eu0.125Gd0.125Tb0.125Dy0.125Ho0.125Ca8(PO4)6F2 (WF-Ln) was successfully synthesized for the first time. Furthermore, electron beam irradiation studies probed by XRD, FTIR, Raman, and X-ray absorption (XAS) spectroscopy implied the radiation resistance nature of this substituted CaFAps up to 20 MGy.
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Affiliation(s)
- Pratik Das
- Product
Development Division, Bhabha Atomic Research
Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Bal Govind Vats
- Fuel
Chemistry Division, Bhabha Atomic Research
Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Pradeep Samui
- Product
Development Division, Bhabha Atomic Research
Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Abhishek Kumar Rai
- Product
Development Division, Bhabha Atomic Research
Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Ashok Kumar Yadav
- Atomic
& Molecular Physics Division, Bhabha
Atomic Research Centre, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
| | - Muhammed Shafeeq
- Fuel
Chemistry Division, Bhabha Atomic Research
Centre, Trombay, Mumbai 400085, India
| | - Swayam Kesari
- Solid
State Physics Division, Bhabha Atomic Research
Centre, Mumbai 400085, India
| | - Suresh Chandra Parida
- Product
Development Division, Bhabha Atomic Research
Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute (HBNI), Mumbai 400094, India
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Samanta SK, Das P, Sengupta A, Acharya R. Optimization of external (in air) particle induced gamma-ray emission (PIGE) methodology for rapid, non-destructive, and simultaneous quantification of fluorine, sodium, and phosphorus in nuclear waste immobilization matrices. RSC Adv 2022; 12:32684-32692. [DOI: 10.1039/d2ra06163e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 10/25/2022] [Indexed: 11/16/2022] Open
Abstract
External (in air) PIGE methodology has been optimized for rapid quantification of fluorine, sodium, and phosphorus in fluorapatite waste immobilization matrices for Molten Salt Reactor (MSR).
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Affiliation(s)
- S. K. Samanta
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
- HomiBhabha National Institute, Department of Atomic Energy, Mumbai-400094, India
| | - P. Das
- Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
- HomiBhabha National Institute, Department of Atomic Energy, Mumbai-400094, India
| | - A. Sengupta
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
- HomiBhabha National Institute, Department of Atomic Energy, Mumbai-400094, India
| | - R. Acharya
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
- HomiBhabha National Institute, Department of Atomic Energy, Mumbai-400094, India
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