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Title: Structural evolution and stability of Sc2(WO4)3 after discharge in a sodium-based electrochemical cell
Authors: Andersen, HL
Al Bahri, OK
Tsarev, S
Johannessen, B
Schulz, B
Liu, JN
Brand, HEA
Christensen, M
Sharma, N
Keywords: Electrochemical cells
Thermal expansion
Sodium compounds
X-ray diffraction
X-ray spectroscopy
Issue Date: 13-Dec-2017
Publisher: Royal Society of Chemistry
Citation: Andersen, H. L., Al Bahri, O. K., Tsarev, S., Johannessen, B., Schulz, B., Liu, J., Brand, H. E. A., Christensen, M. & Sharma, N. (2018). Structural evolution and stability of Sc 2 (WO 4) 3 after discharge in a sodium-based electrochemical cell. Dalton Transactions, 47(4), 1251-1260. doi:10.1039/C7DT04374K
Abstract: Sc2(WO4)3, prepared by solid state synthesis and constructed as an electrode, is discharged to different states in half-cell batteries, versus a Na negative electrode. The structural evolution of the Na-containing electrodes is studied with synchrotron powder X-ray diffraction (PXRD) revealing an increase in microstrain and a gradual amorphization taking place with increasing Na content in the electrode. This indicates that a conversion reaction takes place in the electrochemical cell. X-ray absorption spectroscopy (XAS) at the tungsten L3 absorption edge shows a reduction in the tungsten oxidation state. Variable temperature (VT) PXRD shows that the Sc2(WO4)3 electrode remains relatively stable at higher temperatures, while the Na-containing samples undergo a number of phase transitions and/or turn amorphous above ∼400 °C. Although, Sc2(WO4)3 is a negative thermal expansion (NTE) material only a subtle change of the thermal expansion is found below 400 °C for the Na-containing electrodes. This work shows the complexity in employing an electrochemical cell to produce Na-containing Sc2(WO4)3 and the subsequent phase transitions. © 2018 The Royal Society of Chemistry.
ISSN: 1477-9266
Appears in Collections:Journal Articles

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