Phase Relations in the System Y2O3—CaO—B2O3.

The subsolidus phase relations of the system Y2O3 -CaO-B2O3 are investigated by means of X-ray diffraction (XRD) analyses. There are six binary compounds and three ternary compounds in this system. The phase diagram comprises 13 three-phase regions. The ternary compound CaYBO4 is refined from powder XRD data by the Rietveld method. It has a warwickite-like structure with cell parameters a=10.4354(3) Angstrom, b=9.6126(2) Angstrom, c=3.5880(1) Angstrom and space group Nam. The rationality of the CaYBO4 structure is examined by Brown bond valence model and IR spectra. (C) 2001 Elsevier Science BY. All rights reserved.