期刊
JOURNAL OF ELECTROCERAMICS
卷 46, 期 2, 页码 -出版社
SPRINGER
DOI: 10.1007/s10832-021-00243-w
关键词
Tungsten substituted bismuth oxide; Sillenite phase; Mixed phases; Oxide electrolyte; Variable temperature Raman spectroscopy; Ionic conductivity
资金
- National Research Foundation [78555, 99003, 105852]
- DST/NRF Centre of Excellence in Strong Materials
- University of the Witwatersrand
The equilibrium phases of the Bi2O3-WO3 system were systematically investigated, showing that WO3 content and annealing temperature play a significant role in phase formation. The dominant phase was found to be 7Bi(2)O(3)-2WO(3), and the ionic conductivity of mixed-phase materials was only about three times lower than that of pure WO3 at 700 degrees C.
Equilibrium phases of the Bi2O3-WO3 system, synthesized using the citrate-gel method with slow cooling, have been systematically investigated for samples with 22-27 mol% WO3. Annealing temperature and content of WO3 were shown to play a significant role in the phases present. Both powder X-ray diffraction and Raman spectroscopy revealed that the room temperature equilibrium phases were 7Bi(2)O(3)-WO3 and 7Bi(2)O(3)-2WO(3), with the latter being dominant. Variable temperature Raman spectroscopy showed that both these phases were present up to 850 degrees C, with the possible formation of a third unidentified phase at higher temperatures. The ionic conductivities of the mixed-phase materials were between that for the pure 7Bi(2)O(3)-WO3 and 7Bi(2)O(3)-2WO(3) phases and at 700 degrees C was only about three times lower than that of the pure defect fluorite phase of the 22 mol% WO3 samples. The Arrhenius plots showed no sudden increase in conductivity between 300 and 750 degrees C providing evidence that no major phase change occurred in this temperature range.
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