Structural properties, thermodynamic stability and reaction pathways for solid-state synthesis of Bi₂WO₆ polymorphs

Area of Science:

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

Background:

• Bismuth tungstate (Bi2WO6) is a key Aurivillius oxide with potential applications.
• Understanding its different structural phases and their properties is crucial for material design.
• Investigating synthesis routes is essential for practical material production.

Purpose of the Study:

• To investigate the structural, electronic, optical, and thermodynamic properties of Bi2WO6 polymorphs using DFT.
• To analyze the phase stability, competition, and potential coexistence of different Bi2WO6 structures.
• To explore feasible reaction pathways for the solid-state synthesis of Bi2WO6.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Analysis of electronic band structure, optical properties (dielectric function, absorption spectra).
• Calculations of elastic, phonon, effective mass, and Gibbs free energies.
• Construction of a chemical reaction network for synthesis pathway analysis.

Main Results:

• Three Bi2WO6 polymorphs (P1, P2, P3) exhibit distinct electronic band gaps (2.339 eV, 2.312 eV, 2.128 eV).
• All phases are mechanically and dynamically stable; P1 shows highest stiffness, P3 potentially better charge mobility.
• P1 is the most stable phase at low temperatures; low-cost synthesis pathways from Bi2O3 and WO3 were identified.

Conclusions:

• DFT provides comprehensive insights into Bi2WO6 polymorph properties and phase behavior.
• The identified synthesis routes offer practical strategies for Bi2WO6 production.
• This work aids in understanding and optimizing Bi2WO6 for various applications.