Two novel acentric borate fluorides: M3B6O11F2 (M = Sr, Ba)

Area of Science:

• Inorganic Chemistry
• Materials Science
• Crystallography

Background:

• Borate fluorides are an emerging class of materials with potential optical applications.
• Understanding the structure-property relationships in novel borates is crucial for materials design.
• Noncentrosymmetric structures are essential for nonlinear optical (NLO) properties.

Purpose of the Study:

• To synthesize and characterize novel noncentrosymmetric borate fluorides.
• To determine the crystal structures of Sr(3)B(6)O(11)F(2) and Ba(3)B(6)O(11)F(2).
• To investigate the potential of these compounds for deep-ultraviolet nonlinear-optical applications.

Main Methods:

• Hydrothermal synthesis was employed to obtain single crystals.
• Single-crystal X-ray diffraction was used for structure determination.
• Optical transparency was measured to assess suitability for UV applications.

Main Results:

• Two novel, isostructural borate fluorides, Sr(3)B(6)O(11)F(2) and Ba(3)B(6)O(11)F(2), were successfully synthesized.
• The crystal structures reveal a complex triple-ring borate framework with aligned triangular [BO(3)] groups, imparting polarity.
• Fluorine atoms are coordinated to alkaline-earth metals, differentiating them from hydrated borates.
• The compounds exhibit transparency down to approximately 200 nm.

Conclusions:

• The synthesized borate fluorides possess unique polar structures.
• Their deep-ultraviolet transparency makes them promising candidates for nonlinear-optical devices.
• This work expands the library of noncentrosymmetric inorganic materials for optical applications.