Structures and Nonlinear Optical Properties of Two Acentric Borates with Cubic Cage-like Frameworks

Area of Science:

• Inorganic Chemistry
• Materials Science
• Crystallography

Background:

• Acentric borates are crucial for nonlinear optical (NLO) applications.
• Developing novel borate structures with unique framework topologies is an ongoing challenge.
• Interpenetrating frameworks are rarely observed in borate structural chemistry.

Purpose of the Study:

• To synthesize and characterize new acentric borates with cage-like frameworks.
• To investigate the structural features, specifically interpenetrating anionic and cationic frameworks.
• To evaluate the potential of these new materials as deep ultraviolet (UV) nonlinear optical crystals.

Main Methods:

• Hydrothermal synthesis was employed to obtain crystalline samples of the new borates.
• X-ray diffraction techniques were used to determine the crystal structures.
• Optical properties, including second harmonic generation (SHG) and UV-Vis absorption, were measured.

Main Results:

• Two new acentric borates, Li2Sr0.5[B3(BO3)4] (1) and Na4[Al3(BO3)4]·Cl (2), were successfully synthesized.
• Both compounds exhibit novel interpenetrating polyhedral cubic unit (pcu) anionic and cationic frameworks, rarely seen in borates.
• Moderate second harmonic generation (SHG) responses and short cutoff edges were observed.

Conclusions:

• The synthesized borates possess unique structural characteristics with interpenetrating frameworks.
• Their optical properties suggest potential applications as deep ultraviolet nonlinear optical (NLO) materials.
• Further research into structure-property relationships could lead to optimized NLO crystal design.