Ba3YB3O9: phase transition and crystal structure

A new modification of the compound Ba3YB3O9, β phase, has been attained through solid phase transition from α phase at 1125-1134 deg. C. β-Ba3YB3O9 crystallizes in the hexagonal space group R3-bar with cell parameters a=13.0529(8) A, c=9.5359(9) A. The crystal structure of α-Ba3YB3O9 has been determined from powder X-ray diffraction (XRD) data. The refinement was carried out using the Rietveld methods and the final refinement converged with Rp=8.8%, and Rwp=11.8% with Rexp=5.65%. In its structure, the isolated [BO3]3- anionic groups are parallel to each other and distributed layer upon layer along the c-axis. The Y atoms are six-coordinated by the O atoms to form octahedra. The result of IR spectrum confirmed the existence of [BO3]3- triangular groups