Synthesis, crystal structure and properties of a new strontium cadmium diborate

A new compound, SrCdB2O5, has been grown by the high temperature solution method from the SrO–Cd–B2O3 system for the first time. It crystallizes in the orthorhombic system, space group Pbca with unit-cell parameters a = 12.010(4) Å, b = 5.795(2) Å, c = 12.677(4) Å, Z = 8, volume = 882.4(5) Å3. Its structure is solved by the direct methods and refined to R1 = 0.0256 and wR2 = 0.0727. The new structure contains an infinite three-dimensional matrix that is built from B2O5 units and CdO6 and SrO9 polyhedra. Spectrum properties, thermal analysis and theoretical calculations on electronic structure of SrCdB2O5 were reported.

In the structure, two planar BO3 triangles are formed isolated B2O5 by sharing O atoms. Each CdO6 octahedron is vertex-connected to six BO3 triangles, in which only two BO3 triangles form B2O5 group by sharing one O atom. And each Sr atom is located in the space.Figure optionsDownload as PowerPoint slideHighlights
► SrCdB2O5 has been found in the SrO–CdO–B2O3 system for the first time.
► The UV–Vis–NIR diffuse-reflectance spectrum shows that the ultraviolet cutoff edge for the SrCdB2O5 crystal is about 235 nm.
► SrCdB2O5 is a direct (G–G) gap crystal with the gap Eg = 3.471 eV.