U在烧绿石Nd₂Zr₂O₇中的固化研究
Study on the Solubility of Uranium in the Pyrochlore Lattice of Nd₂Zr₂O₇

DOI: 10.12677/MS.2015.54025, PP. 184-190

Keywords: 烧绿石，锕系核素，U，晶体结构
Pyrochlore, Actinides, Uranium, Crystal Structure

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Abstract:

以具有较强抗辐照和化学稳定性的锆基烧绿石Nd₂Zr₂O₇为固化基材，针对锕系核素U进行固化研究。以硝酸盐作为原料，通过柠檬酸络合和喷雾热解的方法，在1200℃保温12 h成功制备了含U 10 mol%的烧绿石固化体。产物经X-射线粉末衍射、拉曼光谱进行表征，结果表明：U很好的包容到烧绿石固化体中，固化体保持单一的烧绿石结构；U离子半径小于Nd，导致固化体晶格常数减小；随着U成分的增加，固化体的烧绿石结构趋向于无序化。
The solubility of Uranium in pryochlore Nd₂Zr₂O₇ has been studied using zirconate pyrochlores as potential material for use in the high level nuclear waste because of their chemical and radi- ation stabilities. Uranium-doped Pyrochlore Nd1.9U0.1Zr2O7 was synthesized at 1200？C for 12 h by sol-spray pyrolysis method using nitrate and citrate acid as raw materials. The phase compositions of the products were characterized by powder XRD, SEM, Raman spectrum. The results reveal that Uranium has been incorporated in the lattice of Nd2Zr2O7, while maintaining the single pyrochlore structure. The lattice parameter decreases for Nd2Zr2O7 pyrochlore with increase in Uranium content because the effective ionic radius of U is less than that of Nd3+. With increasing Uranium content, the degree of crystal structural disorder increases.

References

[1]	Ringwood, A.E., Kesson, S.E., Ware, N.G., et al. (1979) Immobilization of high level nuclear reactor wastes in SYNROC. Nature, 278, 219. http://dx.doi.org/10.1038/278219a0
[2]	Wang, S.X., Begg, B.D., Wang, L.M., et al. (1999) Radiation stability of gadolinium zirconate: A waste form for plutonium disposition. Journal of Materials Re-search, 14, 4470-4473. http://dx.doi.org/10.1557/JMR.1999.0606
[3]	Lian, J., Wang, L.M., Haire, R.G., et al. (2004) Ion beam irradiation in La2Zr2O7-Ce2Zr2O7 pyrochlore. Nuclear Instruments and Methods in Physics Research Section B, 218, 236-243. http://dx.doi.org/10.1016/j.nimb.2004.01.007
[4]	Lang, M., Zhang, F.X., Ewing, R.C., et al. (2009) Structure modifications of Gd2Zr2-xTixO7 pyochlore induced by swift heavy ions: Disordering and amor-phization. Journal of Materials Research, 24, 1322-1334. http://dx.doi.org/10.1557/jmr.2009.0151
[5]	Yamazaki, S., Yamashita, T., Matsui, T., et al. (2001) Thermal ex-pansion and solubility limits of plutonium-doped lanthanum zirconates. Journal of Nuclear Materials, 294, 183-187. http://dx.doi.org/10.1016/S0022-3115(01)00464-0
[6]	Belin, R.C., Valenza, P.J., Raison, P.E. and Tillard, M. (2008) Synthesis and Rietveld structure refinement of americium pyrochlore Am2Zr2O7. Journal of Alloys and Com-pounds, 448, 321-324. http://dx.doi.org/10.1016/j.jallcom.2006.11.107
[7]	Mandal, B.P., Pandey, M., Tyagi, A.K., et al. (2010) Gd2Zr2O7 pyrochlore: Potential host matrix for some constituents of thoria based reactor’s waste. Journal of Nuclear Materials, 406, 238-246. http://dx.doi.org/10.1016/j.jnucmat.2010.08.042
[8]	Mandal, B.P., Garg, N., Sharma, S.M., et al. (2009) Solu-bility of ThO2 in Gd2Zr2O7 pyrochlore: XRD, SEM and Raman spectroscopic studies. Journal of Nuclear Materials, 392, 95-99. http://dx.doi.org/10.1016/j.jnucmat.2009.03.050
[9]	Lian, J., Zu, X.T., Kutty, K., et al. (2002) Ion-irradiation-induced amorphization of La2Zr2O7 pyrochlore. Physical Review B, 66, 054108. http://dx.doi.org/10.1103/PhysRevB.66.054108
[10]	Wang, S.X., Lumpkin, G.R., Wang, L.M., Ewing, R.C., et al. (2000) Ion irradiation-induced amorphization of six zirconolite compositions. Nuclear Instruments and Methods in Physics Research Section B, 166-167, 293-298. http://dx.doi.org/10.1016/S0168-583X(99)00665-5
[11]	West, A.R. (1974) Solid State Chemistry and Its Appli-cations. Wiley, New York, 172.
[12]	Hess, N.J., Begg, B.D., Conradson, S.D., et al. (2002) Spectroscopic investiga-tions of the structural phase transition in Gd2(Ti1-yZry) 2O7 pyrochlores. Journal of Physical Chemistry B, 106, 4663-4677. http://dx.doi.org/10.1021/jp014285t
[13]	Kong L.G., Karatchevtseva, I., Gregg, D., et al. (2013) Gd2Zr2O7 and Nd2Zr2O7 pyrochlore prepared by aqueous chemical synthesis. Journal of the European Ceramic Society, 33, 3273-3285. http://dx.doi.org/10.1016/j.jeurceramsoc.2013.05.011
[14]	Brown, S., Gupta, H.C., Alonso, A.J., et al. (2004) Lattice dynamical study of optical modes in Tl2Mn2O7 and In2Mn2O7 pyrochlores. Physical Review B, 69, 054434. http://dx.doi.org/10.1103/PhysRevB.69.054434
[15]	王烈林, 谢华, 江阔, 等 (2014) 喷雾热解合成An2Zr2O7(An=La、Nd)烧绿石及结构分析. 核化学与放射化学, 36, 241-246.
[16]	Vandenborre, M.T., Husson, E., Chatry, J.P., et al. (1983) Rare-earth titanates and stannates of pyrochlore structure; Vibrational spectra and force fields. Journal of Raman Spectroscopy, 14, 63-71. http://dx.doi.org/10.1002/jrs.1250140202
[17]	王烈林, 谢华, 陈青云, 等 (2015) 锆基烧绿石Nd2Zr2O7固化锕系核素钍. 无机材料学报, 30, 81-86.

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