Ionic conductivity and crystal structure relationships in Ti/Cu substituted Bi4V2O11 |
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Authors: | M H Paydar A M Hadian G Fafilek |
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Affiliation: | (1) Department of Metallurgy and Material Sciences Eng., School of Eng., Shiraz University, Shiraz, Iran;(2) Department of Metallurgy and Material Sciences, Faculty of Eng., University of Tehran, Tehran, Iran;(3) Institute of Technical Electrochemistry and Solid State Chemistry, University of Technology of Vienna, Getreidemarkt 9/158, 1060 Vienna, Austria |
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Abstract: | Crystal structure and oxide ion conductivity of a series of Ti and Ti-Cu double substituted Bi4V2O11 compounds, Bi2V(1–x)Ti
x
O(11–x)/2 (0.085 x 0.15), and Bi2V0.9Cu(0.1–x)TixO5.35+x
(0 x 0.1), were investigated using X-ray powder diffraction and ac impedance spectroscopy in the temperature and frequency range of 100–700°C and 10–2–107 Hz, respectively.Structural phase transitions, and , occur as a function of composition in Ti substituted compounds for which the is evidenced to be stable at room temperature when x exceeds 0.125. For all Ti-Cu double substituted compounds studied, the room temperature phase was identified to be phase.The required amount of Ti for phase stabilization at room temperature was significantly reduced and the conductivity improved when Cu substituted a part of Ti. Therefore, for the Bi2V0.9Cu(0.1–x)Ti
x
O5.35+x
(0 x 0.075) compounds the ionic conductivity increased and activation energy decreased with decreasing x. At low temperature, the highest ion conductivity was obtained for Bi2V0.9Cu0.1O5.35. At high temperature (T>500°C), a different behavior was observed. The total conductivity increased at first with decreasing x values down to x = 0.05 and then decreased. The maximum conductivity was obtained for Bi2V0.9Cu0.05Ti0.05O5.4, and the activation energy decreased with decreasing x values, such as what happened at low temperature. |
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