Ordering of Defects, Thermodynamic and Transport Properties of Solid Oxide Electrolytes with Fluorite Structure

Abstract

The solid solution MO, + MeO, (M = Zr, Hf, Ce, T h ; Me = Ca, Sr, Sc, Y, the lanthanides) is considered. A model describing the defect structure of a crystal with consideration of short-range order in the arrangement of defects is proposed. The defect interaction is expressed in the pairwise approximation. The short-range order is characterized by the mean probability of finding a dopant cation in the site nearest to the oxygen vacancy. This probability is calculated using the minimum free energy condition. On the basis of the proposed model expressions are derived for the chemical potentials of components and for the ionic conductivity of the system as a function of composition. The calculated curves are in good agreement with the experimental ones. PaCCMOTpeH TBepnbIB MO, + MeO, (M = Zr, Hf, Ce, T h ; Me = Ca, Sr, SC, Y, JlaHTaHOHnbI). npe&TIOXeHa M O H e n b , Il03BOJrHIorrlaH OIlHCaTb He4eHTHyIO CTpYIETYPy paCTBOp KpmTanna npti yseTe 6 n~m~e r o rIopsxEm B pacnonomeHmm ne$emoB. B3aHMOp&iCTBHe rrocneaHmx ~~~E I C~I B~~T C I I B napHoM n p~6 n~w e~r n~; 6nHm~11B nopxno~ xapamepa-3YeTCR CpeHHefi BepORTHOCTbIo HaXO?KneHHFI IIpkiMeCHOrO KaTHOHa B y3m, 6JIHlrradIIIeM K BaKaHCHEl HElCJIOpO~a. 3Ta BepOHTHOCTb paCCsllTaHa 113 YCJIOBHR MHHHMYMa cBO6OHHOfi 3HeprHM. Ha OCHOBe Ilpej&TIOmeHHOB MOHenkl IlOJIy4eHbI BbIpameHElR HJIH XHM119eCIiIIX nOTeHUHaJIOB KOMIlOHeHTOB, a TaHlKe QJIH ElOHHOfi npOBOnHMOCT11 CEl CTeMbI B 3aB11CMMOCT11 OT COCTBBB. PaCueTHbIe Hp11BbIe COrJlaCyIoTCR C 3HCnepHMeIITaJlbIIbIMH.

Origin of the hump on the left shoulder of the X-ray diffraction peaks observed in Y2O3-fully and partially stabilized ZrO2

“…That activation energy of the conductivity before aging increases with increased dopant concentrations supports this explanation [35]. Many studies explained these phenomena by suggesting that the formation of association of dopant ions with OIV due to coulombic forces reduces the mobility of OIV without support of experimental results [69][70][71][72][73]. My results show that these explanations should be reconsidered.…”

Doped Ceria Based Solid Oxide Fuel Cell Electrolytes and their Sintering Aspects: An Overview

“…( 30) as all other terms are constant. Chebotin et al [94] proposed a model describing the defect structure with short-range order in the doped fluorite lattice whereas Nakamura et al [93] expressed the electrical conductivity in terms of probability of vacancy jumps between anion sites having various numbers of adjacent cation ions. The derived electrical conductivity as a function of dopant concentration showed a maximum at a certain concentration as in the case of an experiment.…”