Equilibrium structure of δ-Bi(2)O(3) from first principles

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Science

Background:

• Delta-bismuth oxide (δ-Bi2O3) is a promising material with a fluorite structure.
• Understanding oxygen vacancy ordering is crucial for its properties.

Purpose of the Study:

• To systematically investigate the structural stability of δ-Bi2O3 with varying oxygen vacancy arrangements.
• To elucidate the factors contributing to phase stability.

Main Methods:

• Ab initio calculations were employed to study different oxygen vacancy ordering models.
• Analysis included radial distribution functions and bonding analysis.

Main Results:

• The combined [220] and [400] oxygen vacancy ordering represents the most stable configuration.
• Radial distribution functions distinguish between ordered (discrete) and random (continuous) configurations.
• Local relaxations up to 28.6% in random configurations influence distribution functions.

Conclusions:

• The most stable structure of δ-Bi2O3 involves specific oxygen vacancy ordering.
• Electron lone-pair charges in the Bi-O matrix likely stabilize this ordered configuration.
• Structural stability is intrinsically linked to bonding characteristics.