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Title: Probing disorder in pyrochlore oxides using in situ synchrotron diffraction from levitated solids–A thermodynamic perspective

Abstract

Pyrochlore, an ordered derivative of the defect fluorite structure, shows complex disordering behavior as a function of composition, temperature, pressure, and radiation damage. We propose a thermodynamic model to calculate the disordering enthalpies for several RE 2Zr 2O 7 (RE = Sm, Eu, Gd) pyrochlores from experimental site distribution data obtained by in situ high temperature synchrotron X-ray diffraction. Site occupancies show a gradual increase in disorder on both cation and anion sublattices with increasing temperature and even greater disorder is achieved close to the phase transition to defect fluorite. The enthalpy associated with cation disorder depends on the radius of the rare earth ion, while the enthalpy of oxygen disordering is relatively constant for different compositions. The experimental data support trends predicted by ab initio calculations, but the obtained enthalpies of disordering are less endothermic than the predicted values. Thermal expansion coefficients are in the range (8.6-10.8) x 10 -6 K -1. These new experimental determinations of defect formation energies are important for understanding the stability of pyrochlore oxides and their disordering mechanisms, which are essential in the context of their potential applications in nuclear waste management and other technologies.

Authors:
ORCiD logo; ORCiD logo; ; ; ORCiD logo
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1459466
Alternate Identifier(s):
OSTI ID: 1480857
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Published Article
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Name: Scientific Reports Journal Volume: 8 Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United Kingdom
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Maram, Pardha S., Ushakov, Sergey V., Weber, Richard J. K., Benmore, Chris J., and Navrotsky, Alexandra. Probing disorder in pyrochlore oxides using in situ synchrotron diffraction from levitated solids–A thermodynamic perspective. United Kingdom: N. p., 2018. Web. doi:10.1038/s41598-018-28877-x.
Maram, Pardha S., Ushakov, Sergey V., Weber, Richard J. K., Benmore, Chris J., & Navrotsky, Alexandra. Probing disorder in pyrochlore oxides using in situ synchrotron diffraction from levitated solids–A thermodynamic perspective. United Kingdom. doi:10.1038/s41598-018-28877-x.
Maram, Pardha S., Ushakov, Sergey V., Weber, Richard J. K., Benmore, Chris J., and Navrotsky, Alexandra. Fri . "Probing disorder in pyrochlore oxides using in situ synchrotron diffraction from levitated solids–A thermodynamic perspective". United Kingdom. doi:10.1038/s41598-018-28877-x.
@article{osti_1459466,
title = {Probing disorder in pyrochlore oxides using in situ synchrotron diffraction from levitated solids–A thermodynamic perspective},
author = {Maram, Pardha S. and Ushakov, Sergey V. and Weber, Richard J. K. and Benmore, Chris J. and Navrotsky, Alexandra},
abstractNote = {Pyrochlore, an ordered derivative of the defect fluorite structure, shows complex disordering behavior as a function of composition, temperature, pressure, and radiation damage. We propose a thermodynamic model to calculate the disordering enthalpies for several RE2Zr2O7 (RE = Sm, Eu, Gd) pyrochlores from experimental site distribution data obtained by in situ high temperature synchrotron X-ray diffraction. Site occupancies show a gradual increase in disorder on both cation and anion sublattices with increasing temperature and even greater disorder is achieved close to the phase transition to defect fluorite. The enthalpy associated with cation disorder depends on the radius of the rare earth ion, while the enthalpy of oxygen disordering is relatively constant for different compositions. The experimental data support trends predicted by ab initio calculations, but the obtained enthalpies of disordering are less endothermic than the predicted values. Thermal expansion coefficients are in the range (8.6-10.8) x 10-6 K-1. These new experimental determinations of defect formation energies are important for understanding the stability of pyrochlore oxides and their disordering mechanisms, which are essential in the context of their potential applications in nuclear waste management and other technologies.},
doi = {10.1038/s41598-018-28877-x},
journal = {Scientific Reports},
number = 1,
volume = 8,
place = {United Kingdom},
year = {2018},
month = {7}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1038/s41598-018-28877-x

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Cited by: 4 works
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    Works referencing / citing this record:

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    journal, December 2010

    • Weber, J. K. R.; Benmore, C. J.; Jennings, G.
    • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 624, Issue 3
    • DOI: 10.1016/j.nima.2010.09.125

    Defect formation energies in A 2 B 2 O 7 pyrochlores
    journal, October 2015


    First-principles calculation of defect formation energies and electronic properties in stannate pyrochlores
    journal, November 2008

    • Chen, Z. J.; Xiao, H. Y.; Zu, X. T.
    • Journal of Applied Physics, Vol. 104, Issue 9
    • DOI: 10.1063/1.3000558

    Synthesis of a metallic mesoporous pyrochlore as a catalyst for lithium–O2 batteries
    journal, November 2012

    • Oh, Si Hyoung; Black, Robert; Pomerantseva, Ekaterina
    • Nature Chemistry, Vol. 4, Issue 12, p. 1004-1010
    • DOI: 10.1038/nchem.1499

    Radiation-induced amorphization resistance and radiation tolerance in structurally related oxides
    journal, February 2007

    • Sickafus, Kurt E.; Grimes, Robin W.; Valdez, James A.
    • Nature Materials, Vol. 6, Issue 3
    • DOI: 10.1038/nmat1842

    Nuclear waste disposal—pyrochlore (A2B2O7): Nuclear waste form for the immobilization of plutonium and “minor” actinides
    journal, June 2004

    • Ewing, Rodney C.; Weber, William J.; Lian, Jie
    • Journal of Applied Physics, Vol. 95, Issue 11
    • DOI: 10.1063/1.1707213

    Whole powder pattern decomposition methods and applications: A retrospection
    journal, December 2005


    Aerodynamic levitator for in situ x-ray structure measurements on high temperature and molten nuclear fuel materials
    journal, July 2016

    • Weber, J. K. R.; Tamalonis, A.; Benmore, C. J.
    • Review of Scientific Instruments, Vol. 87, Issue 7
    • DOI: 10.1063/1.4955210

    Levitation apparatus for structural studies of high temperature liquids using synchrotron radiation
    journal, September 1997

    • Krishnan, Shankar; Felten, John J.; Rix, James E.
    • Review of Scientific Instruments, Vol. 68, Issue 9
    • DOI: 10.1063/1.1148315

    Structure and Thermal Expansion of YSZ and La 2 Zr 2 O 7 Above 1500°C from Neutron Diffraction on Levitated Samples
    journal, July 2015

    • Ushakov, Sergey V.; Navrotsky, Alexandra; Weber, Richard J. K.
    • Journal of the American Ceramic Society, Vol. 98, Issue 10
    • DOI: 10.1111/jace.13767

    Thermal Conductivity and Thermal Expansion Coefficients of the Lanthanum Rare-Earth-Element Zirconate System
    journal, August 2003


    Two-dimensional detector software: From real detector to idealised image or two-theta scan
    journal, January 1996

    • Hammersley, A. P.; Svensson, S. O.; Hanfland, M.
    • High Pressure Research, Vol. 14, Issue 4-6, p. 235-248
    • DOI: 10.1080/08957959608201408

    Disorder in Pyrochlore Oxides
    journal, August 2000


    Ionic Conductivity of Ln2 + x Zr2 − x O7 − x/2 (Ln = Sm-Gd) Solid Solutions
    journal, August 2005


    Effects of the synthesis procedure, doping and non-stoichiometry on the order–disorder transformation in LnTiO (Ln=Tm–Lu) oxygen-ion conductors
    journal, September 2005


    Neutron Powder Diffraction Studies of Fluorite and Pyrochlore NdxZr1−xO2−x/2 Solid Solutions with 0.25<x<0.55
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    • Van Dijk, T.; Helmholdt, R. B.; Burggraaf, A. J.
    • physica status solidi (b), Vol. 101, Issue 2
    • DOI: 10.1002/pssb.2221010239

    Intricate disorder in defect fluorite/pyrochlore: a concord of chemistry and crystallography
    journal, June 2017


    Oxide pyrochlores — A review
    journal, January 1983

    • Subramanian, M. A.; Aravamudan, G.; Subba Rao, G. V.
    • Progress in Solid State Chemistry, Vol. 15, Issue 2
    • DOI: 10.1016/0079-6786(83)90001-8

    Atomic disorder in Gd 2 Zr 2 O 7 pyrochlore
    journal, May 2015

    • Zhang, F. X.; Lang, M.; Ewing, R. C.
    • Applied Physics Letters, Vol. 106, Issue 19
    • DOI: 10.1063/1.4921268

    Etude de la transformation ordre-desordre de la structure fluorite a la structure pyrochlore pour des phases (1−x) ZrO2  x Ln2O3
    journal, November 1974


    Thermal expansion behaviour of some rare earth oxide pyrochlores
    journal, July 1994


    Intricate disorder
    journal, February 2016


    Probing disorder in isometric pyrochlore and related complex oxides
    journal, February 2016

    • Shamblin, Jacob; Feygenson, Mikhail; Neuefeind, Joerg
    • Nature Materials, Vol. 15, Issue 5
    • DOI: 10.1038/nmat4581

    Thermochemistry of lanthanum zirconate pyrochlore
    journal, November 2009

    • Radha, A. V.; Ushakov, Sergey V.; Navrotsky, Alexandra
    • Journal of Materials Research, Vol. 24, Issue 11
    • DOI: 10.1557/jmr.2009.0401

    The thermodynamics of cation distributions in simple spinels
    journal, November 1967


    Structure and thermal expansion of Lu2O3 and Yb2O3 up to the melting points
    journal, November 2017


    Nuclear wasteform materials: Atomistic simulation case studies
    journal, October 2013


    In Situ Diffraction from Levitated Solids Under Extreme Conditions—Structure and Thermal Expansion in the Eu 2 O 3 –ZrO 2 System
    journal, December 2014

    • Maram, Pardha S.; Ushakov, Sergey V.; Weber, Richard J. K.
    • Journal of the American Ceramic Society, Vol. 98, Issue 4
    • DOI: 10.1111/jace.13422

    Aero‐acoustic levitation: A method for containerless liquid‐phase processing at high temperatures
    journal, February 1994

    • Weber, J. K. Richard; Hampton, D. Scott; Merkley, Dennis R.
    • Review of Scientific Instruments, Vol. 65, Issue 2
    • DOI: 10.1063/1.1145157

    Similar local order in disordered fluorite and aperiodic pyrochlore structures
    journal, February 2018


    Heat capacity for the Eu2Zr2O7 and phase relations in the ZrO2–Eu2O3 system: Experimental studies and calculations
    journal, April 2013


    Effect of non-stoichiometry and synthesis temperature on the structure and conductivity of Ln2+xM2−xO7−x/2 (Ln=Sm–Gd; M=Zr, Hf; x=0–0.286)☆
    journal, January 2007


    Radiation Tolerance of Complex Oxides
    journal, August 2000


    Direct Measurement of Surface Dissolution Rates in Potential Nuclear Waste Forms: The Example of Pyrochlore
    journal, August 2015

    • Fischer, Cornelius; Finkeldei, Sarah; Brandt, Felix
    • ACS Applied Materials & Interfaces, Vol. 7, Issue 32
    • DOI: 10.1021/acsami.5b04281

    Fluorite-pyrochlore transformation in Eu2Zr2O7—direct calorimetric measurement of phase transition, formation and surface enthalpies
    journal, January 2012

    • Saradhi, M. P.; Ushakov, S. V.; Navrotsky, A.
    • RSC Advances, Vol. 2, Issue 8
    • DOI: 10.1039/c2ra00727d

    Drop-and-catch (DnC) calorimetry using aerodynamic levitation and laser heating
    journal, October 2016

    • Ushakov, Sergey V.; Shvarev, Alexey; Alexeev, Timur
    • Journal of the American Ceramic Society, Vol. 100, Issue 2
    • DOI: 10.1111/jace.14594