Boron Oxide Nanoparticles Exhibiting Defect-Activated Photoluminescence

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Chemistry

Background:

• Engineering emissive defects in boron-based materials is crucial for advanced optics and sensing.
• Developing fluorescent or phosphorescent compounds requires precise control over material properties.

Purpose of the Study:

• To report a bottom-up synthesis of pure boron oxide nanoparticles from crystalline boron.
• To investigate the formation of emissive defects and their influence on nanoparticle fluorescence.
• To establish a green and scalable method for producing defect-engineered boron oxide nanoparticles.

Main Methods:

• A two-step synthesis involving ultrasonication of boron powder in water followed by thermal annealing in air.
• Characterization of nanoparticle composition and defect structures.
• Analysis of fluorescence properties modulated by annealing temperature and defect concentration.

Main Results:

• Successfully synthesized pure boron oxide nanoparticles without organic solvents or contaminants.
• Identified nonstoichiometric oxo-hydroxy BOH compounds formed during ultrasonication.
• Demonstrated that annealing temperature controls defect formation, primarily nonbridging oxygen in trigonal BO3 units, which enhances fluorescence.
• Established a correlation between defect density and nanoparticle luminescence.

Conclusions:

• The developed method provides a controlled and environmentally friendly route to synthesize fluorescent boron oxide nanoparticles.
• Defect engineering, specifically the creation of nonbridging oxygen defects, is a viable strategy to tune the optical properties of boron oxide nanoparticles.
• These nanoparticles hold potential for applications in optics and sensing due to their tunable fluorescence.