Structure determination of a new compound LiCaBO3

A new compound, LiCaBO3, has been identified in the system Li2O-CaO-B2O3 and high-quality single crystals were obtained by the flux method. Its structure has been solved and refined from single crystal and powder X-ray diffraction data, respectively. This compound crystallizes in an orthorhombic unit cell (space group Pbca) with lattice parameters a=13.227(13) A, b=6.1675(6) A, and c=6.0620(6) A. There are 8 formulas per unit cell and 6 unique atoms sites in the unit. Its structure is stacked alternately with [LiBO] and [CaO] layers along the [100] direction. In the [LiBO] layers, the isolated [BO3]3- anionic groups, distributed along two directions, [011] and [01-bar1], are almost perpendicular to each other. The differences among the structures of the four compounds, LiCaBO3, LiMgBO3, LiSrBO3 and LiBaBO3 have been discussed, and the infrared spectra of LiCaBO3 has also been researched, which is consistent with the crystallographic study