Abstract

KIEFER, Mathias A. et al. A detailed investigation of the structural stability, ionic conductivity and in situ δ-phase formation of Y_xBi_2xO₃. S.Afr.j.chem. (Online) [online]. 2022, vol.76, pp.111-119. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2022/v76a16.

The in situ δ-phase formation for a series of yttrium-doped Bi₂O₃ materials was studied by Raman spectroscopy and high resolution X-ray diffraction under variable temperature conditions. Contrary to previous reports, for dopant concentrations less than 25%, the cubic ô-phase was not fully stabilized at room temperature - tetragonal phase content was evident in both Raman spectra and powder diffractograms. Arrhenius plots also showed evidence of a phase transformation by the distinct large step change in conductivity in the temperature region where the tetragonal-cubic phase transformation was noted. Both the thermal expansion and ionic conductivity of the cubic phase decreased with increasing dopant content.

Keywords : bismuth oxide; impedance spectroscopy; oxide ion conductor; powder X-ray diffraction; raman spectroscopy.