Study of phase relationships in the Sr3(PO4)2-CePO4 system. Phase diagram and thermal characteristics of phases

A diagram representing phase relationships in the Sr-3(PO4)(2)-CePO4 phosphate system has been developed on the basis of results obtained by thermal analysis (DTA/DSC/TGA) and X-ray diffraction (XRD) methods. One intermediate compound with the formula Sr3Ce(PO4)(3) occurs in the Sr-3(PO4)(2)-CePO4 system at temperatures exceeding 1045 degrees C. The compound has a eulytite structure with the following structural parameters: a=b=c=10.1655(8) angstrom, alpha=beta=gamma=90.00 degrees, V=1050.46(6) angstrom(3). It's melting point exceeds 1950 degrees C. A limited solid solution exists in the system, which possesses the structure of a low-temperature form of Sr-3(PO4)(2). At 1000 degrees C the maximal concentration of CePO4 in the solid solution is below 20 mol%. The solid solution phase field narrows with increased temperature. There is a eutectic point in the {Sr-3(PO4)(2)+Sr3Ce(PO4)(3)} phase field at 1765 degrees C and 15 mol% of CePO4. The melting temperature of Sr-3(PO4)(2) is 1882 + 15 degrees C. (C) 2013 Elsevier Inc. All rights reserved.