OALibJ  Vol.1 No.3 , June 2014
First-Principles Study on Cation-Antisite Defects of Stannate and Titanate Pyrochlores
Abstract: The structure and formation energies of cation antisite defects for a series of stannate pyrochlores A2Sn2O7 (A = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Lu, and Y) and titanate pyrochlores A2Ti2O7 (A = La, Sm, Gd, Tb, Dy, Ho, Er, Lu, and Y) have been systematically investigated using the first-principles total energy calculations. The calculated results reveal that the lattice parameters increase and the oxygen positional parameters decrease with increasing ionic radii of the lanthanides in the stannate and titanate pyrochlore compounds, respectively. The results suggest that cation antisite defects in pyrochlore play an important role in determining their radiation-resistant properties. The present studies indicate formation energies of cation antisite defects are not simple functions of ionic radius, radius ratio, lattice parameters, and the oxygen positional parameters.
Cite this paper: Chen, L. , Su, X. and Li, Y. (2014) First-Principles Study on Cation-Antisite Defects of Stannate and Titanate Pyrochlores. Open Access Library Journal, 1, 1-8. doi: 10.4236/oalib.1100516.

[1]   Ewing, R., Weber, W. and Clinard, F. (1995) Radiation Effects in Nuclear Waste Forms for High-Level Radioactive Waste. Progress in Nuclear Energy, 29, 63-127.

[2]   Ewing, C., Weber, W. and Lian, J. (2004) Nuclear Waste Disposal—Pyrochlore (A2B2O7): Nuclear Waste Form for the Immobilization of Plutonium and “Minor” Actinides. Journal of Applied Physics, 95, 5949-5971.

[3]   Wang, S.X., Begg, B.D., Wang, L.M., Ewing, R.C., Weber, W.J. and Govidan Kutty, K.V. (1999) Radiation Stability of Gadolinium Zirconate: A Waste Form for Plutonium Disposition. Journal of Materials Research, 14, 4470-4473.

[4]   Sickafus, K.E., Grimes, R.W., Valdez, J.A., Cleave, A., Tang, M., Ishimaru, M., Corish, S.M., Stanek, C.R. and Uberuaga, B.P. (2007) Radiation-Induced Amorphization Resistance and Radiation Tolerance in Structurally Related Oxides. Nature Materials, 6, 217-223.

[5]   Begg, B.D., Hess, N.J., Weber, W.J., Devanathan, R., Icenhower, J.P., Thevuthasan, S. and McGrail, B.P. (2001) Heavy-Ion Irradiation Effects on Structures and Acid Dissolution of Pyrochlores. Journal of Nuclear Materials, 288, 208-216.

[6]   Vance, E.R., Lumpkin, G.R., Carter, M.L., Cassidy, D.J., Ball, C.J., Day, R.A. and Begg, B.D. (2002) Incorporation of Uranium in Zirconolite (CaZrTi2O7). Journal of the American Ceramic Society, 85, 1853-1859.

[7]   Lian, J., Chen, J., Wang, L., Ewing, R., Farmer, J., Boatner, L. and Helean, K. (2003) Radiation-Induced Amorphization of Rare-Earth Titanate Pyrochlores. Physical Review B, 68, Article ID: 134107.

[8]   Lian, J., Zu, X., Kutty, K., Chen, J., Wang, L. and Ewing, R. (2002) Ion-Irradiation-Induced Amorphization of La2Zr2O7 Pyrochlore. Physical Review B, 66, Article ID: 054108.

[9]   Lian, J., Helean, K., Kennedy, B., Wang, L., Navrotsky, A. and Ewing, R. (2006) Effect of Structure and Thermodynamic Stability on the Response of Lanthanide Stannate Pyrochlores to Ion Beam Irradiation. Journal of Physical Chemistry B, 110, 2343-2350.

[10]   Jiang, C., Stanek, C., Sickafus, K. and Uberuaga, B. (2009) First-Principles Prediction of Disordering Tendencies in Pyrochlore Oxides. Physical Review B, 79, Article ID: 104203.

[11]   Marks, N.A., Thomas, B.S., Smith, K.L. and Lumpkin, G.R. (2008) Thermal Spike Recrystallisation: Molecular Dynamics Simulation of Radiation Damage in Polymorphs of Titania. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 266, 2665-2670.

[12]   Weber, W., Ewing, R., Catlow, C., Rubia, T.D., Hobbs, L., Kinoshita, C., Matzke, H., Motta, A., Nastasi, M. and Salje, E. (1998) Radiation Effects in Crystalline Ceramics for the Immobilization of High-Level Nuclear Waste and Plutonium. Journal of Materials Research, 13, 1434-1484.

[13]   Chen, Z.J., Xiao, H.Y., Zu, X.T. and Gao, F. (2008) First-Principles Calculation of Defect Formation Energies and Electronic Properties in Stannate Pyrochlores. Journal of Applied Physics, 104, Article ID: 093702.

[14]   Xiao, H.Y., Zu, X.T., Gao, F. and Weber, W.J. (2008) First-Principles Study of Energetic and Electronic Properties of A2Ti2O7 (A = Sm, Gd, Er) Pyrochlore. Journal of Applied Physics, 104, Article ID: 073503.

[15]   Zhang, Z., Xiao, H., Zu, X.T., Gao, F. and Weber, W.J. (2009) First-Principles Calculation of Structural and Energetic Properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La). Journal of Materials Research, 24, 1335-1341.

[16]   Panero, W.R., Stixrude, L. and Ewing, R. (2004) First-Principles Calculation of Defect-Formation Energies in the Y2(Ti,Sn,Zr)2O7 Pyrochlore. Physical Review B, 70, Article ID: 054110.

[17]   Li, N., Xiao, H.Y., Zu, X.T., Wang, L.M., Ewing, R.C., Lian, J. and Gao, F. (2007) First-Principles Study of Electronic Properties of La2Hf2O7 and Gd2Hf2O7. Journal of Applied Physics, 102, Article ID: 063704.

[18]   Minervini, L., Grimes, R.W. and Sickafus, K.E. (2000) Disorder in Pyrochlore Oxides. Journal of the American Ceramic Society, 83, 1873-1878.

[19]   Lian, J., Weber, W.J., Jiang, W., Wang, L.M., Boatner, L.A. and Ewing, R.C. (2006) Radiation-Induced Effects in Pyrochlores and Nanoscale Materials Engineering. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 250, 128-136.

[20]   Sickafus, K., Minervini, L., Grimes, R.W., Valdez, J.A., Ishimaru, M., Li, F., McClellan, K.J. and Hartmann, T. (2000) Radiation Tolerance of Complex Oxides. Science, 289, 748-751.

[21]   Lumpkin, G.R., Smith, K.L. and Blackford, M.G. (2001) Heavy Ion Irradiation Studies of Columbite, Brannerite, and Pyrochlore Structure Types. Journal of Nuclear Materials, 289, 177-187.

[22]   Lumpkin, G.R., Pruneda, M., Rios, S., Smith, K.L., Trachenko, K., Whittle, K.R. and Zaluzec, N.J. (2007) Nature of the Chemical Bond and Prediction of Radiation Tolerance in Pyrochlore and Defect Fluorite Compounds. Journal of Solid State Chemistry, 180, 1512-1518.

[23]   Xiao, H.Y., Gao, F. and Weber, W.J. (2010) Threshold Displacement Energies and Defect Formation Energies in Y2Ti2O7. Journal of Physics: Condensed Matter, 22, Article ID: 415801.

[24]   Li, Y.H., Uberuaga, B., Jiang, C., Choudhury, S., Valdez, J., Patel, M., Won, J., Wang, Y.Q., Tang, M., Safarik, D., Byler, D., McClellan, K., Usov, I.O., Hartmann, T., Baldinozzi, G. and Sickafus, K.E. (2012) Role of Antisite Disorder on Preamorphization Swelling in Titanate Pyrochlores. Physical Review Letters, 108, Article ID: 195504.

[25]   Kresse, G. and Hafner, J. (1993) Ab Initio Molecular Dynamics for Liquid Metals. Physical Review B, 47, 558-561.

[26]   Kresse, G., Hafner, J. and Needs, R. (1992) Optimized Norm-Conserving Pseudopotentials. Journal of Physics: Condensed Matter, 4, 7451.

[27]   Kresse, G. and Furthmüller, J. (1996) Efficiency of ab Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Computational Materials Science, 6, 15-50.

[28]   Kresse, G. and Furthmüller, J. (1996) Efficient Iterative Schemes for ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Physical Review B, 54, Article ID: 11169.

[29]   Blöchl, P.E. (1994) Projector Augmented-Wave Method. Physical Review B, 50, Article ID: 17953.

[30]   Kresse, G. and Joubert, D. (1999) From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method. Physical Review B, 59, 1758.

[31]   Perdew, J.P., Chevary, J., Vosko, S., Jackson, K.A., Pederson, M.R., Singh, D. and Fiolhais, C. (1992) Atoms, Molecules, Solids, and Surfaces: Applications of the Generalized Gradient Approximation for Exchange and Correlation. Physical Review B, 46, 6671.

[32]   Lian, J., Wang, L., Wang, S., Chen, J., Boatner, L. and Ewing, R. (2001) Nanoscale Manipulation of Pyrochlore: New Nanocomposite Ionic Conductors. Physical Review Letters, 87, Article ID: 145901.

[33]   Subramanian, M., Aravamudan, G. and Subba Rao, G. (1983) Oxide Pyrochlores—A Review. Progress in Solid State Chemistry, 15, 55-143.

[34]   Kennedy, B.J. (1997) Structural Trends in Pyrochlore-Type Oxides. Physica B: Condensed Matter, 241-243, 303-310.

[35]   Brisse, F. and Knop, O. (1968) Pyrochlores. III. X-Ray, Neutron, Infrared, and Dielectric Studies of A2Sn2O7 Stannates. Canadian Journal of Chemistry, 46, 859-873.

[36]   Chen, Z.J., Xiao, H., Zu, X., Wang, L., Gao, F., Lian, J. and Ewing, R. (2008) Structural and Bonding Properties of Stannate Pyrochlores: A Density Functional Theory Investigation. Computational Materials Science, 42, 653-658.

[37]   Xiao, H.Y., Wang, L.M., Zu, X.T., Lian, J. and Ewing, R.C. (2007) Theoretical Investigation of Structural, Energetic and Electronic Properties of Titanate Pyrochlores. Journal of Physics: Condensed Matter, 19, Article ID: 346203.