Structural characterization of (Bi_1-xGd_x)₁₄W₂O₂₇ (x = 0.00 and 0.05) synthesized via mechano-thermal treatment

ABSTRACT

Samples of (Bi_1-xGd_x)₁₄W₂O₂₇ (x = 0 and 0.05) compounds were prepared via a combination of mechanochemical and thermal treatments upon a Bi₂O₃/WO₃/Gd₂O₃ stoichiometric mixture of precursors. Phase evolution, as well as the determination of structural parameters in as-prepared compounds, were performed by XRD analysis. Rietveld refinement revealed that gadolinium ions are incorporated into the tetragonal structure of Bi₁₄W₂O₂₇ with preference to occupy octahedrally coordinated Bi³⁺ sites. The Gd doping induced an increase in Bi sites coordination, i.e., the number of oxygens around Bi/Gd ions increased, which can be explained by the absence of 6s² lone pair electrons in gadolinium ions.

Keywords:

• Bismuth tungstate
• X-ray diffraction
• Rietveld refinement
• lone pair electron 6s²