Mullite-derivative Bi2Mn(x)Al(7-x)O14 (x~1): structure determination by powder X-ray diffraction from a multi-phase...

Area of Science:

• Materials Science
• Crystallography
• Solid-State Chemistry

Background:

• Powder X-ray diffraction (XRD) is increasingly used for crystal structure determination, especially when single crystals are unavailable.
• Intermediate phases in material decomposition can be challenging to isolate and characterize.

Purpose of the Study:

• To determine the crystal structure of the metastable intermediate phase Bi(2)Mn(x)Al(7-x)O(14) (x~1).
• To demonstrate a strategy for structure determination from multi-phase powder XRD data.

Main Methods:

• Structure determination using powder X-ray diffraction (XRD).
• Modified Le Bail fitting with known impurity structures for improved intensity extraction.
• Charge-flipping algorithm and Monte-Carlo simulated annealing for full structural model acquisition.

Main Results:

• The crystal structure of the intermediate phase Bi(2)Mn(x)Al(7-x)O(14) was successfully determined from a multi-phase sample.
• A modified Le Bail fitting approach enhanced intensity extraction from complex powder XRD patterns.
• The determined structure is mullite-related, featuring specific arrangements of tetrahedral and octahedral sites for Mn and Al.

Conclusions:

• The developed strategy is effective for determining structures from multi-phase powder XRD data, even for metastable compounds.
• This approach is broadly applicable to complex materials, not limited to oxides.
• The study highlights the utility of powder XRD in overcoming challenges in single-crystal diffraction.