A₃Sc(PO₄)₂ (A = Li, Na): rare earth cations effectively regulate phosphate structures for enhanced birefringence

Area of Science:

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

Background:

• Phosphates exhibit diverse structures and properties, finding applications as ionic conductors, phosphors, and nonlinear optical materials.
• Developing novel phosphates with tailored properties remains an active area of research.

Purpose of the Study:

• To computationally predict novel rare earth phosphates with enhanced optical properties.
• To investigate the electronic structure and optical characteristics of A3Sc(PO4)2 (A = Li, Na).

Main Methods:

• Artificial Bee Colony (ABC) algorithm for structural prediction.
• Ab initio total-energy calculations for electronic structure and properties.
• Real-space atom-cutting (RSAC) analysis for property origin.

Main Results:

• Successful prediction of two novel rare earth phosphates: Li3Sc(PO4)2 and Na3Sc(PO4)2.
• These compounds exhibit large bandgaps (Li3Sc(PO4)2: 6.077 eV, Na3Sc(PO4)2: 5.085 eV) and improved birefringence (Li3Sc(PO4)2: 0.046, Na3Sc(PO4)2: 0.058 at 1064 nm).
• Birefringence is primarily attributed to the ScO6 group.

Conclusions:

• The predicted rare earth phosphates offer a desirable combination of large bandgap and suitable birefringence.
• Introducing rare earth cations is an effective strategy for designing phosphates with balanced optical properties.