Ca₇(TeO₃)₆(MoO₄): A Promising Mid-Infrared Nonlinear Optical Crystal Activated via a Module-Oriented Dimensionality...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Photonics

Background:

• High-performing nonlinear optical (NLO) crystals are crucial for laser technologies but face challenges due to trade-offs in performance metrics.
• Developing novel NLO materials with superior properties remains a significant research area.

Purpose of the Study:

• To report a new quasi-zero-dimensional (0D) tellurite molybdate NLO crystal, Ca7(TeO3)6(MoO4) (CTMO).
• To engineer CTMO using a module-oriented dimensionality reduction strategy.
• To investigate the NLO properties and structural characteristics of CTMO.

Main Methods:

• Employing a module-oriented dimensionality reduction strategy for crystal engineering.
• Characterizing the crystal structure and identifying unique group ratios (Te-O to Mo-O = 6).
• Measuring optical properties including UV-Vis cutoff, bandgap, laser-induced damage threshold, second harmonic generation (SHG) response, birefringence, and IR absorption.

Main Results:

• CTMO exhibits a record-shortest UV cutoff edge (266 nm) and a high bandgap (4.66 eV) among acentric molybdates.
• Achieved a laser-induced damage threshold 42 times higher than AgGaS2.
• Demonstrated a strong SHG response (approx. 8.6 × KDP) and desirable birefringence (0.092@1064 nm) with extended IR absorption beyond 7.0 μm.
• Synergistic effects between [TeO3] and [MoO4] modules contribute to balanced NLO properties.

Conclusions:

• CTMO represents a significant advancement in NLO materials, particularly for mid-IR applications.
• The discovery facilitates the use of acentric oxides as mid-IR NLO crystals.
• The developed strategy provides a rational approach for designing novel NLO crystals with enhanced overall performance.