ATOMISTIC COMPUTER SIMULATION OF THE MIXING PROPERTIES OF ZIRCON ZrSiO4 — MONAZITE LaPO4 AND ZIRCON ZrSiO4 — XENOTIME YPO4 SOLID SOLUTIONS

UDC 548.4

https://doi.org/10.15407/mineraljournal.38.03.047

Grechanovsky A.E. (1), Eremin N.N. (2)
(1) M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine
34, Acad. Palladina Pr., Kyiv-142, Ukraine, 03680
E-mail: grechanovsky@gmail.com
(2) Lomonosov Moscow State University
1, Leninsky Gory, GSP-2, Moscow, Russia, 119992
E-mail: neremin@geol.msu.ru
ATOMISTIC COMPUTER SIMULATION OF THE MIXING PROPERTIES OF ZIRCON ZrSiO4 — MONAZITE LaPO4 AND ZIRCON ZrSiO4 — XENOTIME YPO4 SOLID SOLUTIONS
Language: Russian
Mineralogical journal 2016, 38 (3): 47-55

Abstract: At present, aluminophosphate or borosilicate glasses have been used as matrices for spent fuel. However they are not enough stable for immobilization of long-living high-level waste (HLW). An alternative for nuclear waste vitrification is utilization of HLW in ceramic matrices and minerals. Among them the natural rare-earth orthophosphates LnPO4 (Ln is a lanthanide or yttrium) with the structure of monazite or zircon and their artificial analogues. The objective of this work was a computer study of mixing properties of the solid solutions ZrSiO4 — YPO4 and ZrSiO4 — LaPO4 using interatomic potentials within the framework of semiclassic approach. Calculations have been performed for pure components, and also for 24 intermediate compositions for ZrSiO4 — YPO4 system and for 14 intermediate compositions for ZrSiO4 — LaPO4 system on the "Lomonosov" supercomputer in supposition of disordered configurations of solid solutions. The mixing properties have been calculated over the entire range of compositions. It is shown that configuration entropy make a decisive contribution to the total mixing entropy and that the vibrational contribution is no more than 7 % from total value of mixing entropy. Obtained data allowed construct dependence of Gibbs free energy from composition of solid solutions at different tempe ratures. On the basis of analytical treatment of these data the regions of stability of the solid solutions have been estimated. It is shown that beginning of solubility in the zircon—xenotime system corresponds to the temperature 800 K. At temperatures 1000, 1200 and 1800 Kelvin the solubility limit is 5, 7 and 12 mol. % xenotime in zircon and 7, 10 and 17 mol. % zircon in xenotime. On the other hand, beginning of solubility in the system of zircon—monazite corresponds to the temperature 1200 K. The solubility limit of monazite in zircon was estimated to 1 % at a temperature 1800 K. The obtained results agree with experimental data.

Keywords: radiation mineralogy, atomistic computer simulation, solid solutions, mixing properties, zircon.

References:

  1. Grechanovsky, A.E., Brik, A.B., Urusov, V.S., Eremin, N.N., Radchuk, V.V. and Shabalin, B.G. (2014), Mineral. Journ. (Ukraine), Kyiv, Vol. 36 No 1, pp. 3-11.
  2. Eremin, N.N., Grechanovsky, A.E., Talis, R.A. and Urusov, V.S. (2012), Teorija i praktika sovremennoj nauki, Materialy VII Mezhdunar. nauch.-prakt. konf., 3-4 oct. 2012): In 7 t., Izd-vo Spetskniga, T. 1., Moscow, RU, pp. 70-80, available at: http://www.rf-conf.ru/arhiv.php
  3. Laverov, N.P., Yudintsev, S.V., Livshits, T.S., Stefanovsky, S.V., Lukinykh, A.N. and Ewing, R.C. (2010), Geokhimiya, Moscow, Vol. 48 No 1, pp. 3-16.
  4. Laverov, N.P., Yudintsev, S.V., Stefanovsky, S.V. and Ewing, R.C. (2012), Dokl. Akad. Nauk, Vol. 443 No 6, pp. 1-6.
  5. Heermann, D.W. (1990), Metody komp’yuternogo eksperimenta v teoreticheskoy fizike, Nauka, Moscow, 176 p.
  6. Yudintsev, S.V., Stefanovsky, S.V. and Nikonov, B.S. (2014), Dokl. Akad. Nauk, Vol. 454 No 2, pp. 211-215. https://doi.org/10.7868/S0869565214020236
  7. Chakoumakos, B.C., Murakami, T., Lumpkin, G.R. and Ewing, R.C. (1987), Science, Vol. 236, pp. 1556-1559. https://doi.org/10.1126/science.236.4808.1556
  8. Eremin, N.N., Deyanov, R.Z. and Urusov, V.S. (2008), Glass Physics and Chemistry, Vol. 34 No 1, pp. 9-18. https://doi.org/10.1134/S1087659608010021
  9. Eremin, N., Protasov, N. and Grechanovsky, A. (2015), Acta Cryst. Section A, Vol. 71 No A1, pp. S333-S334. https://doi.org/10.1107/S2053273315094991
  10. Ewing, R.C., Lutze, W. and Weber, W.J. (1995), J. Mater. Res., Vol. 10, pp. 243-246. https://doi.org/10.1557/JMR.1995.0243
  11. Ewing, R.C., Weber, W.J. and Clinard, F.W. (1995), Progr. Nucl. Energy, Vol. 29 No 2, pp. 63-127. https://doi.org/10.1016/0149-1970(94)00016-Y 
  12. Gale, J.D. and Rohl, A.L. (2003), Mol. Simul., Vol. 29 No 5, pp. 291-341. https://doi.org/10.1080/0892702031000104887
  13. Grechanovsky, A.E., Eremin, N.N. and Urusov, V.S. (2013), Physics of the Solid State, Vol. 55 No 9, pp. 1929-1935. https://doi.org/10.1134/S1063783413090138
  14. Gromalova, N.A., Eremin, N.N. and Urusov, V.S. (2011), Glass Physics and Chemistry, Vol. 37 No 3, pp. 293-306. https://doi.org/10.1134/S1087659611030059
  15. Hanchar, J.M., Finch, R.J., Hoskin, P.W.O., Watson, E.B., Cherniak, D.J. and Mariano, A.N. (2001), Amer. Miner., Vol. 86, pp. 667-680. https://doi.org/10.2138/am-2001-5-607
  16. Meldrum, A., Boatner, L.A. and Ewing, R.C. (1997), Phys. Rev. B, Vol. 56 No 21, pp. 13805-13814. https://doi.org/10.1103/PhysRevB.56.13805
  17. Meldrum, A., Zinkle, S.J., Boatner, L.A. and Ewing, R.C. (1999), Phys. Rev. B, Vol. 59 No 6, pp. 3981-3992. https://doi.org/10.1103/PhysRevB.59.3981
  18. Mullica, D.F., Grossie, D.A. and Boatner, L.A. (1985), J. Solid State Chem., Vol. 58 No 1, pp. 71-77. https://doi.org/10.1016/0022-4596(85)90269-5
  19. Mullica, D.F., Sappenfield, E.L. and Boatner, L.A. (1990), Inorganica Chimica Acta, Vol. 174, pp. 155-159. https://doi.org/10.1016/S0020-1693(00)80293-5
  20. Ni, Y., Hughes, J.M. and Mariano, A.N. (1995), Amer. Miner., Vol. 80 No 1/2, pp. 21-26. https://doi.org/10.2138/am-1995-1-203
  21. Urusov, V.S. and Eremin, N.N. (2015), J. Structural Chemistry, Vol. 56 No 4, pp. 737-751. https://doi.org/10.1134/S0022476615040186
  22. Urusov, V.S., Grechanovsky, A.E. and Eremin, N.N. (2012), Glass Physics and Chemistry, Vol. 38 No 1, pp. 55-62. https://doi.org/10.1134/S1087659612010178
English