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Abstract
The electrical properties of the entropy stabilized oxides: Zr6Nb2O17, Zr6Ta2O17, Hf6Nb2O17 and Hf6Ta2O17 were characterized. The results and the electrical properties of the products (i.e. ZrO2, HfO2, Nb2O5 and Ta2O5) led us to hypothesize the A6B2O17 family is a series of mixed ionic-electronic conductors. Conductivity measurements in varying oxygen partial pressure were performed on A6Nb2O17 and A6Ta2O17. The results indicate that electrons are involved in conduction in A6Nb2O17 while holes play a role in conduction of A6Ta2O17. Between 900 °C–950 °C, the charge transport in the A6B2O17 system increases in Ar atmosphere. A combination of DTA/DSC and in situ high temperature X-ray diffraction was performed to identify a potential mechanism for this increase. In-situ high temperature X-ray diffraction in Ar does not show any phase transformation. Based on this, it is hypothesized that a change in the oxygen sub-lattice is the cause for the shift in high temperature conduction above 900 °C–950 °C. This could be: (i) Nb(Ta)4+- oxygen vacancy associate formation/dissociation, (ii) formation of oxygen/oxygen vacancy complexes (iii) ordering/disordering of oxygen vacancies and/or (iv) oxygen-based superstructure commensurate or incommensurate transitions. In-situ high temperature neutron diffraction up to 1050 °C is required to help elucidate the origins of this large increase in conductivity.
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Authors (6)
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William Foute Rosenberg
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Scott J. McCormack
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- Category:
- Articles
- Type:
- artykuły w czasopismach
- Published in:
-
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
no. 171,
ISSN: 0013-4651 - Language:
- English
- Publication year:
- 2024
- Bibliographic description:
- Miruszewski T., Mielewczyk-Gryń A., Jaworski D., Rosenberg W. F., McCormack S. J., Gazda M.: Charge Transport in the A6B2O17 (A = Zr, Hf; B = Nb, Ta) Superstructure Series// JOURNAL OF THE ELECTROCHEMICAL SOCIETY -,iss. 3 (2024), s.034503-
- DOI:
- Digital Object Identifier (open in new tab) 10.1149/1945-7111/ad2d90
- Sources of funding:
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- Project High entropy oxides for energy conversion
- National Science Foundation in the Directorate for Mathematical and Physical Sciences, under the Division of Materials Research, in the Ceramic program, award number: 2047084
- Verified by:
- Gdańsk University of Technology
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