Rattling-induced suppression of thermal transport in cubic In₂O₃with Sn-Ga diatomic defect

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Indium oxide (In2O3) is a promising transparent conducting oxide.
• Understanding defect properties is crucial for optimizing In2O3-based devices.
• Lattice anharmonicity and phonon transport significantly influence thermal conductivity.

Purpose of the Study:

• Investigate the structural, electronic, phononic, and thermal properties of cubic In2O3 with a specific diatomic defect.
• Analyze the impact of a tin (Sn) and gallium (Ga) defect on phonon behavior and thermal conductivity.
• Elucidate the rattling-like motion of the Sn atom within a cage structure.

Main Methods:

• First-principles calculations using density functional theory (DFT).
• Inclusion of lattice anharmonicity for three-phonon scattering processes.
• Application of the Peierls-Boltzmann transport equation for phonon transport analysis.
• Bader charge analysis and electron localization function for defect characterization.

Main Results:

• A novel diatomic defect (Sn on In-site, Ga on nearest vacancy) was studied.
• A cage structure formed around the defect, inducing rattling-like motion of the Sn atom.
• Phonon spectra showed flattened branches, localized modes, decreased group velocities, and increased three-phonon scattering.
• Calculated thermal conductivity dropped by over seven times at room temperature compared to pristine In2O3.

Conclusions:

• The diatomic Sn-Ga defect dramatically alters phonon dynamics in In2O3.
• The rattling behavior of Sn is key to the observed phonon localization and scattering.
• This defect engineering approach offers a pathway to significantly reduce thermal conductivity in In2O3.