Growth, crystal structure and optical properties of a new layered fluorine beryllium borate, Sr0.23Ca0.77Na2Be2B2O6F2

A novel fluorine beryllium borate crystal Sr0.23Ca0.77Na2Be2B2O6F2 has been grown by high temperature solution method from its self-flux system for the first time. Crystal structure of this compound was determined by single crystal X-ray diffraction. It crystallizes in the trigonal space group R3¯ (No. 148) with lattice parameters a=4.6608(6) Å, c= 27.516(5) Å, Z=3, V= 517.65(13) Å3. The crystal displays a sandwich-like layered configuration along c axis with the infinite (Be6B6O12F3)∞ non-bonding double layer formed by two (Be3B3O6F3)∞ single layers in the a-b plane. The single layer was composed of BO3 triangle and BeO3F tetrahedron, both of which are the most favorable anionic groups in deep ultraviolet (UV) region. The structural relationship between the title compound and related fluorine beryllium borate was discussed. Optical transmittance spectrum reveals this compound has a very wide transmission range (190nm – 8μm). The IR spectrum and thermal behavior of Sr0.23Ca0.77Na2Be2B2O6F2 were also reported.

The crystal displays a sandwich-like layered configuration along c axis with the infinite (Be3B3O6F3)∞ layers in the a-b plane.Figure optionsDownload as PowerPoint slideHighlights
► A new beryllium borate Sr0.23Ca0.77Na2Be2B2O6F2 was synthesized.
► It exhibits a sandwich-like layered structure formed by (Be6B6O12F3)∞ double layers.
► The (Be3B3O6F3)∞ single layer were composed of BO3 triangles and BeO3F tetrahedrons.
► This compound has a very wide transparency range of wavelengths from 190 nm to 8 μm.