Bond-Valence-Driven Model for Highest Infrared-Active Optical Phonon Frequency in Complex Oxides.

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• The highest infrared-active optical phonon frequency (νmax) is crucial for infrared optical properties, thermal transport, and photon-phonon interactions in polar crystals.
• Existing predictive methods for νmax lack accuracy, efficiency, and broad applicability across different material systems.

Purpose of the Study:

• To develop a robust, physics-informed framework for accurate prediction of νmax.
• To extend the framework for predicting temperature and doping effects on νmax.
• To enable the design of infrared-transparent materials with tunable transmission windows.

Main Methods:

• Synergizing bond valence theory with intrinsic crystallographic parameters.
• Validating the model across over 100 complex oxides and 12 doped material systems.
• Extending the framework to incorporate temperature and doping effects.

Main Results:

• Achieved exceptional agreement between predicted and experimental/first-principles-calculated νmax values.
• Demonstrated accurate prediction of infrared absorption edges.
• Showcased the model's ability to predict νmax in doped and temperature-varying systems.

Conclusions:

• The developed framework offers a universal strategy for accelerating the discovery and optimization of infrared optical materials.
• The model facilitates precise tuning of νmax through compositional engineering.
• This work provides a pathway for designing advanced materials for thermal management, photonics, and radiative coatings.