Synthesis, crystal structure and thermal behavior of a novel oxoborate SrBi2B4O10

A new compound, SrBi2B4O10, has been grown by cooling a melt with the stoichiometric composition. It is triclinic, P−1, a=6.819(1), b=6.856(1), c=9.812(2) Å, α=96.09(1), β=109.11(1), γ=101.94(1)°, V=416.5(1) Å3, Z=2. The crystal structure of the compound has been solved by direct methods and refined to R1=0.050 (wR2=0.128). The structure contains Bi–O pseudolayers build up from Bi–O chains involving oxocentred OBi3 triangles. Sr atoms and [B4O9]6− isolated anions (4B:3Δ□:<2Δ□>Δ) are located between the Bi–O packages. The thermal treatment as well as DSC experiment showed that the compound melts above 800 °C presumably according to the peritectic reaction: SrBi2B4O10 ↔ SrB2O4+SrB4O7+ Liquid. According to high-temperature X-ray powder diffraction study thermal expansion of SrBi2B4O10 structure is anisotropic (α11=13, α22=9, α33=2, αV=24×10−6 °C−1).