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A comparative study of the thermodynamic stability of britholites


The apatites have a structure stability and durability under radiation conditions in geological situation and in synthetic products. Thus, britholites, which are phospho-silicate-apatite-containing rare earth elements, are considered to be one of the possible candidates for actinides and fission product immobilization. In this work, a comparative study of the thermochemical stability of four apatite-solid-solutions were performed, which are:

Lanthanum-enclosing silicate-fluorapatites (LaF) Ca(10 − x)Lax(PO4)6 − x(SiO4)xF2
Lanthanum-enclosing silicate-oxyapatites (LaO) Ca(10 − x)Lax(PO4)6 − xSiO4)xO□
Neodymium-enclosing silicate-fluorapatite (NdF) Ca(10 − x)Ndx(PO4)6 − x(SiO4)xF2
Neodymium-enclosing silicate-oxyapatites (NdO) Ca(10 − x)Ndx(PO4)6 − x(SiO4)xO□

with 0 ≤x≤6 is the substitution rate and □ is a vacancy.

It was found that the absolute value of the solution enthalpies at infinite dilution increases with the substitution rate in all studied britholites. This is in agreement with the evolution of the dissociation energies of these apatites, proofing the gain in interatomic cohesion with the double substitution (Ca2+; PO43−) ↔ (Ln3+; SiO44−; Ln: La or Nd). In addition, the entropy of oxybritholite indicates a slight disorder compared to fluorbritholites, and the standard Gibbs free energy of formation reveals the particular stability of oxybritholite, either containing lanthanum or neodymium.

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  1. Alemrajabi M, Rasmuson ÅC, Korkmaz K, Forsberg K (2017) Recovery of rare earth elements from nitrophosphoric acid solutions. Hydrometallurgy 169:253–262.

    Article  Google Scholar 

  2. Ardhaoui K (2020) Standard enthalpies of formation determination of lanthanum fluorbritholites. Mater Sci Eng B: Solid-State Materials for Advanced Technology 261:114661.

    Article  Google Scholar 

  3. Ardhaoui K, Coulet MV, Ben Chérifa A, Carpena J, Rogez J, Jemal M (2006a) Standard enthalpy of formation of neodymium fluorbritholites. Thermochim Acta 444(2):190–194.

    Article  Google Scholar 

  4. Ardhaoui K, Rogez J, Ben Chérifa A, Jemal M, Satre P (2006b) Standard enthalpy of formation of lanthanum oxybritholites. J Therm Anal Calorim 86(2):553.

    Article  Google Scholar 

  5. Ardhaoui K, Ben Chérifa A, Rogez J (2018) Standard enthalpy of formation of Neodymium oxybritholites. 7th International Chemisty Conference (ICC 2018) King Saud University, Riyadh

    Google Scholar 

  6. Bartel CJ, Millican SL, Deml AM, Rumptz JR, Tumas W, Weimer AW, Lany S, Stevanović V, Musgrave CB, Holder AM (2018) Physical descriptor for the Gibbs energy of inorganic crystalline solids and temperature-dependent materials chemistry. Nat Commun 9(1):4168.

    Article  Google Scholar 

  7. Ben Cherifa A, Nounah A, Lacout JL, Jemal M (2001) Synthése et thermochimie de phosphates au cadmium. Thermochim Acta 366(1):1–6.

    Article  Google Scholar 

  8. Berastegui P, Hull S, Garcı Garcı FJ, Grins J (2002) A structural investigation of La2(GeO4)O and alkaline-earth-doped La9.33(GeO4)6O2. J Solid State Chem 168(1):294–305.

    Article  Google Scholar 

  9. Boyer L (1997) Synthesis of phosphate-silicate apatites at atmospheric pressure. Solid State Ionics 95(1–2):121–129.

    Article  Google Scholar 

  10. Dacheux N, du Fou de Kerdaniel E, Clavier N, Podor R, Aupiais J, Szenknect S (2010) Kinetics of dissolution of thorium and uranium doped britholite ceramics. J Nucl Mater 404(1):33–43.

    Article  Google Scholar 

  11. Dachs E, Harlov D, Benisek A (2010) Excess heat capacity and entropy of mixing along the chlorapatite–fluorapatite binary join. Phys Chem Miner 37(9):665–676.

    Article  Google Scholar 

  12. Denton AR, Ashcroft NW (1991) Vegards law. Phys Rev A 43(6):3161–3164.

    Article  Google Scholar 

  13. Drouet C (2015) A comprehensive guide to experimental and predicted thermodynamic properties of phosphate apatite minerals in view of applicative purposes. J Chem Thermodyn 81:143–159.

    Article  Google Scholar 

  14. Dutta T, Kim K-H, Uchimiya M, Kwon EE, Jeon B-H, Deep A, Yun S-T (2016) Global demand for rare earth resources and strategies for green mining. Environ Res 150:182–190.

    Article  Google Scholar 

  15. Ganteaume M, Coten M, Decressac M (1991) Un nouveau calorimetre de solution: Le calsol. Thermochim Acta 178:81–98.

    Article  Google Scholar 

  16. Gedde UW(2020) Gibbs and Helmholtz Free Energies. In: Essential Classical Thermodynamics. SpringerBriefs in Physics. Springer, Cham.

  17. Glasser L, Jenkins HDB (2000) Lattice energies and unit cell volumes of complex ionic solids. J Am Chem Soc 122(4):632–638.

    Article  Google Scholar 

  18. Glasser L, Jenkins HDB (2005) Predictive thermodynamics for condensed phases. Chem Soc Rev 34(10).

  19. Howie RA, Mc Connell D (1974. Apatite: its crystal chemistry, mineralogy, utilization, and geologic and biologic occurrences. Applied Mineralogy, Volume 5. Vienna and New York (Springer-Verlag), 1973. xvi+ III pp., 17 figs. Mineralogical Magazine, 39(305).

  20. Jenkins HD, Glasser L (2003) Standard absolute entropy, S degrees 298 values from volume or density. 1. Inorganic materials. Inorg Chem. 42(26):8702–8. PMID: 14686847

  21. Li MYH, Kwong HT, Williams-Jones AE, Zhou M-F (2021) The thermodynamics of rare earth element liberation, mobilization and supergene enrichment during groundwater-regolith interaction. Geochim Cosmochim Acta.

  22. McDannell KT, Issler DR (2021) Simulating sedimentary burial cycles – Part 1: Investigating the role of apatite fission track annealing kinetics using synthetic data. Geochronology 3(1):321–335.

    Article  Google Scholar 

  23. Peiravi M, Dehghani F, Ackah L, Baharlouei A, Godbold J, Liu J, Mohanty M, Ghosh T (2021) A review of rare-earth elements extraction with emphasis on non-conventional sources: coal and coal byproducts, iron ore tailings, apatite, and phosphate byproducts. Min Metall Explor 38(1):1–26.

    Article  Google Scholar 

  24. Shuller-Nickles L, Bender W, Walker S, Becker U (2014) Quantum-mechanical methods for quantifying incorporation of contaminants in proximal minerals. Minerals 4(3):690–715.

    Article  Google Scholar 

  25. Wagman DD, Evans WH, Parker VB, Schumm RH, Halow I (1982) The NBS Tables of Chemical Thermodynamic Properties. Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units, National Standard Reference Data System.

  26. Yoder CH (2005) Geochemical applications of the simple salt approximation to the lattice energies of complex materials. Am Mineral 90(2–3):488–496.

    Article  Google Scholar 

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Correspondence to Kaouther Ardhaoui.

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This paper was selected from the 3rd Conference of the Arabian Journal of Geosciences (CAJG), Tunisia 2020

Responsible editor: Murat Karakus

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Ardhaoui, K. A comparative study of the thermodynamic stability of britholites. Arab J Geosci 14, 2155 (2021).

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  • Apatites
  • Britholites
  • Entropy
  • Lattice potential energy
  • Enthalpy of solution
  • Standard Gibbs free energy of formation