Structure determination of phi-Bi8Pb5O17 by electron and powder X-ray diffraction

Area of Science:

• Materials Science
• Crystallography
• Solid-State Chemistry

Background:

• Bismuth-lead-oxide (Bi-Pb-O) systems are known to exhibit various structural phases.
• Understanding the precise crystal structure is crucial for developing advanced materials like fast ion conductors.

Purpose of the Study:

• To determine the detailed crystal structure of the phi-Bi8Pb5O17 phase.
• To investigate the atomic arrangement and ordering of bismuth (Bi) and lead (Pb) atoms in this specific phase.
• To compare the determined structure with other known phases in the Bi-Pb-O system.

Main Methods:

• Combined electron diffraction and powder X-ray diffraction (XRD) for structural determination.
• Direct methods and difference Fourier maps utilizing electron diffraction and XRD data.
• Structure refinement using the Rietveld method on powder XRD data.

Main Results:

• The triclinic crystal structure of phi-Bi8Pb5O17 was successfully determined.
• Evidence of an ordered phase where Bi and Pb atoms occupy distinct lattice sites.
• This ordered structure contrasts with the typically observed solid solutions in similar Bi-Pb-O compositions.

Conclusions:

• The phi-Bi8Pb5O17 phase represents a unique ordered structure within the Bi-Pb-O phase diagram.
• The distinct atomic ordering suggests potential for tailored properties in fast ion conductor materials.
• Further research into the formation and properties of this ordered phase is warranted.