Examples



mdbootstrap.com



 
Article
2018

Electronic-Ionic Processes in Bi2Cu0.5Mg0.5Nb2O9 with Pyrochlore Structure


N. A. SekushinN. A. Sekushin, M. S. KorolevaM. S. Koroleva
Russian Journal of Electrochemistry
https://doi.org/10.1134/S1023193518090112
Abstract / Full Text

Solid solution Bi2Cu0.5Mg0.5Nb2O9–δ with the pyrochlore structure is synthesized by three different methods. Its structure and chemical composition are confirmed by X-ray diffraction analysis, electron microscopy, and energy-dispersive spectroscopy. The electronic-ionic processes are studied by the method of impedance spectroscopy in the frequency range from 0.3 Hz to 1.0 MHz and the temperature range from 0 to 340°С. The data are processed with the use of ZView program. Electrochemical models of samples are obtained in the form of equivalent circuits. The sign of the main charge carrier is determined by the thermo-emf method. Nonlinear effects are studied based on voltammetric characteristics. It is found that at room temperature, the charge in samples is transferred by electrons and cations (presumably, copper). In the temperature range of 260–300°С, the capacitance of samples and the specific conductivity of their volume demonstrate local minimums. Insofar as at these temperatures the oxygen conduction may occur, it is assumed that associates of anions and cations are formed. The decrease in the concentration of charge carries is confirmed by sample’s equivalent circuit into which the Gerischer impedance is introduced to enhance the accuracy. It is shown that at t = 260°С, the lifetime of charge carriers is the minimum.

Author information
  • Institute of Chemistry, Komi Scientific Center, Ural Branch, Russian Academy of Sciences, Syktyvkar, 167982, RussiaN. A. Sekushin & M. S. Koroleva
References
  1. Miida, R. and Tanaka, M.A., Modulated structure in a fluorite-type fast-ion-conductor δ-(Bi2O3)1–x(Nb2O5)x, Jap. J. Appl. Phys., 1990, vol. 26, p. 1132.
  2. Zhou W., Microstructures of some Bi–W–Nb–O phases, J. Solid State Chem., 2002, vol. 163, p. 479.
  3. Isupov, V.A., Physical problems of capacitor materials with the pyrochlore structure, Techn. Physics, 1997, vol. 42, no. 10, p. 1155.]
  4. Cann, D.P. and Randall, C.A., Investigation of the dielectric properties of bismuth pyrochlores, Solid State Comm., 1996, vol. 100, p. 529.
  5. Piir, I.V., Prikhodko, D.A., Ignatchenko, S.V., and Schukariov, A.V., Preparation and structural investigations of the mixed bismuth niobates, containing transition metals, Solid State Ionics, 1997, vol. 101–103, p. 1141.
  6. Sekushin, N.A. and Piir, I.V., Synthesis, structure, and relaxation processes in Bi2Mg1–xCuxNb2O9 ion-conduction ceramics, Russ. J. Electrochem., 2011, vol. 47, p. 709.
  7. Piir, I.V., Sekushin, N.A., and Belyi, V.A., Distribution of copper and magnesium atoms on cationic sites of solid solutions Bi2Mg1–xCuxNb2O9–δ with pyrochlore structure, Izvestiya Komi Nauchnogo Centra, Ural Branch, Russ. Academy of Sciences, 2011, no. 4(8), p. 19.
  8. Rodriguez-Carvajal, J., Recent advances in magnetic structure determination by neutron powder diffraction, Phys. B (Amsterdam, Neth.), 1993, vol. 192, nos. 1–2, p. 55.
  9. Krasnov, A.G., Piir, I.V., Koroleva, M.S., Sekushin, N.A., Ryabkov, Y.I., Piskaykina, M.M., Sadykov, V.A., Sadovskaya, E.M., Pelipenko, V.V., and Eremeev, N.F., The conductivity and ionic transport of doped bismuth titanate pyrochlore Bi1.6MxTi2O7 − δ (M–Mg, Sc, Cu), Solid State Ionics, 2017, vol. 302, p. 118.
  10. Ketsko, V.A., Beresnev, E.N., Chmyrev, V.I., Alikhanyan, A.S., Kop’eva, M.A., and Kuznetsov, N.T., Nanoporoshki okisei i reaktsii okisleniya-vosstanovleniya v gelyakh (Nanopowders of Oxides and Redox Reactions in Gels), Moscow: Sputnik, 2011.
  11. Belov, N.V., Kristallografiya (Crystallography), Moscow: Akademiya Nauk SSSR, 1947.
  12. Vanderah, T.A., Levin, I., and Lufaso, M.W., An unexpected crystal-chemical principle for the pyrochlore structure, Eur. J. Inorg. Chem., 2005, vol. 15, p. 2895.
  13. Sekushin, N.A., Method of presentation of experimental data in impedance spectroscopy, Russ. J. Electrochem., 2009, vol. 45. p. 1300.
  14. Ogoreles, Z. and Jviani, J., Current-voltage characteristic of superionic Ag2S in two coexisting phases, Fizika, 1983, vol. 15, no. 4, p. 375.
  15. Ohashi, Y.H., Ohashi, K., Terada, M., and Ohba, Y., Non-linear electrical transport in silver sulfide, J. Phys. Soc. Japan, 1985, vol. 54, no. 2, p. 752.
  16. Seeger K., Semiconductor Physics, Wien: Springer, 1973.
  17. Handbook of Thin Film Technology, Maissel, L.I. and Glang, R., Eds., New York: McGraw Hill, 1970.
  18. Kao, K.C. and Hwang, W., Electrical Transport in Solids with Particular Reference to Organic Semiconductors, Oxford: Pergamon, 1980.
  19. Lasia, A., Electrochemical Impedance Spectroscopy and Its Applications, New York: Springer, 2014.
  20. Oreshkin, P.T. Fizika poluprovodnikov i dielektrikov (Physics of Semiconductors and Dielectrics), Moscow: Vysshaya shkola, 1977.
  21. Boukamp, B.A. and Bouwmeester, H.J.M., Interpretation of the Gerischer impedance in solid state ionics, Solid State Ionics, 2003, vol. 157, nos. 1–4, p. 29.