Synthesis, structure and electrical properties of Li + -doped pyrochlore Gd 2 Zr 2 O 7

Irina A. Anokhina; Irina E. Animitsa; Anastasia F. Buzina; Vladimir I. Voronin; Vladimir B. Vykhodets; Tatyana E. Kurennykh; Yuri P. Zaikov

doi:10.15826/chimtech.2020.7.2.02

Synthesis, structure and electrical properties of Li⁺-doped pyrochlore Gd₂Zr₂O₇

Irina A. Anokhina, Irina E. Animitsa, Anastasia F. Buzina, Vladimir I. Voronin, Vladimir B. Vykhodets, Tatyana E. Kurennykh, Yuri P. Zaikov

Abstract

The pyrochlore Gd_1.55Li_0.45Zr₂O_6.55was prepared by the solution and solid-state methods. The introduction of lithium in the Gd-sublattice led to decrease in the lattice parameter a = 10.4830(8) Å in comparison with Gd₂Zr₂O₇(a =10.5346(2) Å). Monitoring of the lithium content in the sample during heat treatments showed a loss of lithium at temperatures above 1100 °C, so, to maintain the stoichiometry of lithium the low temperature sintering methods are required. The sample Gd_1.55Li_0.45Zr₂O_6.55 exhibited a predominant oxygen-ion transport over a wide range of temperatures. Although doping did not lead to an increase in the oxygen-ion conductivity compared to Gd₂Zr₂O₇, it caused the suppression of the hole conductivity.

Keywords

gadolinium zirconate Gd2Zr2O7, pyrochlore, Li+-doping, conductivity

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References

Merwin A, Williamson MA, Willit JL, Chidambaram D. Review-Metallic lithium and the reduction of actinide oxides. Journal of the Electrochemical Society. 2017;164(8):H5236–46. doi:10.1149/2.0251708jes

Choi EY, Lee J. Complete reduction of high-density UO2 to metallic U in molten Li2O-LiCl. Journal of Nuclear Materials. 2017;494:439–47. doi:10.1016/j.jnucmat.2017.07.036

Willit JL, Miller WE, Battles JE. Electrorefining of uranium and plutonium - A literature review. Journal of Nuclear Materials. 1992;195(3):229–49. doi:10.1016/0022-3115(92)90515-M

Choi EY, Choi IK, Hur JM, Kang DS, Shin HS, Jeong SM. In situ electrochemical measurement of O2- concentration in molten Li2O/LiCl during uranium oxide reduction process. Electrochemical and Solid-State Letters. 2012;15(3):E11–E13. doi:10.1149/2.016203esl

Cho SH, Kim DY, Kwon S, Yoon BH, Lee JH. High-temperature corrosion characteristics of yttria-stabilized zirconia material in molten salts of LiCl-Li2O and LiCl-Li2O-Li. Journal of Nuclear Science and Technology. 2018;55(1):97–103. doi:10.1080/00223131.2017.1383214

Cho SH, Kim SW, Kim DY, Lee JH, Hur JM. Hot corrosion behavior of magnesia-stabilized ceramic material in a lithium molten salt. Journal of Nuclear Materials. 2017;490:85–93. doi:10.1016/j.jnucmat.2017.04.012

Lehmann H, Pitzer D, Pracht G, Vassen R, Stoever D. Thermal conductivity and thermal expansion coefficients of the lanthanum rare-earth-element zirconate system. Journal of the American Ceramic Society. 2003;86(8):1338–44. doi:10.1111/j.1151-2916.2003.tb03473.x

Radha AV, Ushakov SV, Navrotsky A. Thermochemistry of lanthanum zirconate pyrochlore. Journal of Materials Research. 2009;24(11):3350–7. doi:10.1557/jmr.2009.0401

Volkov VN, Vykhodets VB, Golubkov IK, Klotsman SM, Lerkh PV, Pavlov VA. Accurate light ion beam monitoring by backscattering. Nucl Instrum and Meth. 1983;205:73-7. doi:10.1016/0167-5087(83)90175-8

Ziegler JF. Biersack JP. The stopping and ranges of ions in matter. New York: Pergamon Press; 1977.

Vykhodets VB, Klotsman SM, Levin AD. Oxygen diffusion in α-Ti: II. The calculation of the concentration profile of impurities in the nuclear microanalysis. The Phys. Metal & Metallogr. 1987;64:920–4.

Wuensch BJ, Eberman KW, Heremans C, Ku EM, Onnerud P, Yeo EME, Haile SM, Stalick JK, Jorgensen JD. Connection between oxygen-ion conductivity of pyrochlore fuel-cell materials and structural change with composition and temperature. Solid State Ionics. 2000;129:111–33. doi:10.1016/S0167-2738(99)00320-3

Zhang FX, Lang M, and Ewing RC. Atomic disorder in Gd2Zr2O7 pyrochlore. Applied Physics Letters. 2015;106:191902. doi:10.1063/1.4921268

Shannon RD. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst. 1976;A32:751–67. doi:10.1107/S0567739476001551

Michel D, Perez M, Jorba, Collongues R. Etude de la Transformation Ordre–De´sordre de la Structure Fluorite a` la Structure Pyrochlore pour des Phases (1-x) ZrO2 -x Ln2O3. Mater Res Bull. 1974;9:1457–68.

Uehara T, Koto K, Emura S, Kanamaru F. EXAFS study of fluorite and pyrochlore compounds in the system ZrO – GdO. Solid State Ionics. 1987;23:331–7. doi:10.1016/0167-2738(87)90012-9

Scheetz BE, White WB. Characterization of anion disorder in zirconate A2B2O7 compounds by Raman spectroscopy. J. Am. Ceram. Soc. 1979;62:468–70. doi:10.1111/j.1151-2916.1979.tb19107.x

Khal HEl, Cordier A, Batis N, Siebert E, Georges S, Steil MC. Effect of porosity on the electrical conductivity of LAMOX materials. Solid State Ionics. 2017;304:75–84. doi:10.1016/j.ssi.2017.03.028

Catlow CRA. Defects and disorder in crystalline and amorphous solids. Springer Science+Business Media Oordrecht; 1994. doi:10.1007/978-94-011-1942-9

Van Dijk MP, De Vries KJ, Burggraaf AJ. Electrical conductivity and defect chemistry of the system (TbxGd1−x)2Zr2O7+y (O≦x≦1;O≦y<0.25). Solid State Ionics. 1985;16:211–4. doi:10.1016/0167-2738(85)90045-1

DOI: https://doi.org/10.15826/chimtech.2020.7.2.02