Phase Relations in the Y2O3—BaO—B2O3 System.

The subsolidus phase relations of the Y2O3-BaO-B2O3 system are investigated by means of X-ray diffraction (XRD) analyses. The system comprises eight three-phase regions. Nine binary compounds and four ternary compounds are found to exist. The ternary compounds of this system are BaYB9O16, Ba3YB3O9, Ba3Y2B4O12 and BaY3B3O10. The compound BaYB9O16 can be indexed by the DICVOL9I program based on a monoclinic unit cell with lattice parameters a = 15.568(2) Angstrom, b = 3.8934(8) Angstrom, c = 6.745(1) Angstrom and beta = 98.32(1)degrees. A new compound BaY3B3O10 is identified, which has a monoclinic structure with cell parameters a = 17.47(l) Angstrom, b = 4.684(5) Angstrom, c = 13.291(7) Angstrom and beta = 1 10.95(4)degrees. The compound Ba3YB3O9 has two modifications (alpha- and beta-phases), both of which crystallize in the hexagonal system but with different space groups. (C) 2003 Elsevier B.V All rights reserved.