Ordered fluorite phases in the Bi2O3-Ta2O5 system: A structural and electrical investigation

M. Struzik , Marcin Małys , Wojciech Wróbel , I. Abrahams , Franciszek Krok , J.R. Dygas

Abstract

Structure and electrical behaviour are reported for the system Bi1-xTaxO1.5 + x (0.167 ≤ x ≤ 0.250). In the compositional range 0.200 \< x ≤ 0.250 an incommensurately modulated pseudo-cubic phase (type II) is observed, with the appearance of a larger pseudo-cubic phase in the region 0.167 ≤ x ≤ 0.200. Structural analysis of the type II phases by neutron diffraction reveals subtle changes in the oxide ion distribution with temperature, associated with changes in the incommensurate modulation parameter. Analysis of the defect structure of the type II phase reveals chains of tantalate octahedra as a likely structural motif. It is proposed that these chains facilitate an electronic contribution to total conductivity at low temperatures through electron hopping along the chains. Changes in oxide ion vacancy ordering may explain the observed non-linear behaviour in the thermal expansion of lattice parameter and Arrhenius plots of total conductivity.
Author M. Struzik - [Politechnika Warszawska]
M. Struzik,,
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, Marcin Małys (FP / SSID)
Marcin Małys,,
- Solid State Ionics Division
, Wojciech Wróbel (FP / SSID)
Wojciech Wróbel,,
- Solid State Ionics Division
, I. Abrahams - [School of Biological and Chemical Sciences Queen Mary University of London]
I. Abrahams,,
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, Franciszek Krok (FP / SSID)
Franciszek Krok,,
- Solid State Ionics Division
, J.R. Dygas - [Warsaw University of Technology (PW), MNiSW [80]]
J.R. Dygas,,
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- Politechnika Warszawska
Journal seriesSolid State Ionics, ISSN 0167-2738, (A 35 pkt)
Issue year2011
Vol202
No1
Pages22-29
Keywords in EnglishAC impedance spectroscopy, Bismuth oxide, Bismuth tantalum oxide, Defect structure, Neutron diffraction, X-ray diffraction
ASJC Classification3104 Condensed Matter Physics; 2500 General Materials Science; 1600 General Chemistry
DOIDOI:10.1016/j.ssi.2011.08.009
URL http://www.sciencedirect.com/science/article/pii/S0167273811004218
Score (nominal)35
Score sourcejournalList
Publication indicators WoS Citations = 10; Scopus Citations = 10; GS Citations = 11.0; Scopus SNIP (Source Normalised Impact per Paper): 2011 = 1.615; WoS Impact Factor: 2011 = 2.646 (2) - 2011=3.097 (5)
Citation count*11 (2020-01-03)
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