Thermal variation of structure and electrical conductivity in Bi 4YbO7.5
PBN-AR
Instytucja
Wydział Fizyki (Politechnika Warszawska)
Informacje podstawowe
Główny język publikacji
en
Czasopismo
Chemistry of Materials
ISSN
0897-4756
EISSN
Wydawca
American Chemical Society
DOI
Rok publikacji
2013
Numer zeszytu
3
Strony od-do
326-336
Numer tomu
25
Identyfikator DOI
Liczba arkuszy
0.5
Słowa kluczowe
en
Ac impedance spectroscopy; Bismuth oxides; Fluorite structure; Total scattering; Ytterbium oxide, Defect structures; Electric conductivity; Fluorspar; Neutron diffraction; Phase separation; Solid electrolytes; Spectroscopy; Stoichiometry; Thermoanalysis; X ray diffraction; Ytterbium, Ions
Streszczenia
Język
en
Treść
The thermal behavior of the oxide ion-conducting solid electrolyte Bi 4YbO7.5 was investigated using a combination of variable temperature X-ray and neutron powder diffraction, thermal analysis (DTA and TGA), and ac impedance spectroscopy. The title compound shows a fluorite-type structure throughout the measured temperature range (20-850 C), with a phase separation at ca. 600 C into a cubic δ-type phase and an orthorhombic phase of assumed stoichiometry Bi17Yb7O36. This type of transition is a relatively common feature in bismuth oxide-based systems and can limit their practical application. Here, the transition was carefully studied using isothermal measurements, which showed that it is accompanied by changes in oxide-ion stoichiometry, as well as significant disorder in the oxide ion sublattice in the δ-type phase. These results correlate with the observed electrical behavior. Analysis of the total neutron scattering through reverse Monte Carlo (RMC) modeling reveals details of the coordination environments for both cations. The oxide-ion vacancy distribution seems to be consistent with a favoring of âŸ̈100⟠© vacancy pairs, although âŸ̈110⟩ vacancy pairs exhibit the highest frequency as they have the maximum likelihood. A vacancy ordering model based on three vacancies per cell is presented. © 2013 American Chemical Society.
Inne
System-identifier
WUT263103
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