Additive-Triggered Polar Polymorph Formation: β-Sc(IO₃ )₃ , a Promising Next-Generation Mid-Infrared Nonlinear...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Noncentrosymmetric (NCS) solids are crucial for advanced electronic and optical devices.
• Synthesizing NCS materials with desirable properties, especially for nonlinear optics (NLO), presents significant challenges.
• Developing new synthesis strategies for NCS materials is essential for technological advancement.

Purpose of the Study:

• To investigate the role of additives in the synthesis of NCS solids.
• To develop a new metastable NCS material with promising mid-infrared NLO properties.
• To explore the potential of rare-earth iodates for NLO applications.

Main Methods:

• Utilized lithium carbonate (Li₂CO₃) as an additive during the nucleation stage of crystal growth.
• Investigated polymorphism transformation pathways.
• Characterized the optical and structural properties of the synthesized material, including second-harmonic generation (SHG) and optical band gap.

Main Results:

• Li₂CO₃ additive successfully triggered the formation of an NCS precursor, enabling polymorphism transformation.
• Synthesized metastable β-Sc(IO₃)₃ exhibits strong NLO responses (2.2×KTP @ 2100 nm, 16×KDP @ 1064 nm).
• The material possesses a large optical band gap (4.52 eV), sufficient birefringence (Δn=0.219), and wide transparency, attributed to optimal iodate anion alignment.

Conclusions:

• Additives play a critical role in controlling the growth and polymorphism of polar NCS solids.
• The developed synthesis strategy offers a pathway for designing novel NCS materials with enhanced NLO properties.
• Metastable β-Sc(IO₃)₃ is a highly promising candidate for mid-infrared NLO applications.