Phase relation studies in Pb1-xMxF2+x systems(0.0 <= x <= 1.0; M = Nd3+, Eu3+ and Er3+)

摘要

In this communication we report the synthesis and characterization of a series of compounds with the general composition Pb1-xM'F-x(2 + x), (0.0 less than or equal to x less than or equal to 1.0; M' = Nd3+, Eu3+ and Er3+) to elucidate the detailed phase relations between PbF2 and M'F-3. These three rare-earth fluorides were selected so as to delineate the effect of ionic size on the phase relations. In all the three systems, fluorite-type solid solutions are formed at the PbF2 rich end. The solid solubility limits of NdF3, EUF3 and ErF3 in the PbF2 lattice, as observed from this study, are 30, 25 and 15 mol%, respectively. In PbF2-NdF3 system, beyond the fluorite-type solid solutions, NdF3 phase is observed. However, in both PbF2-EuF3 and PbF2-ErF3 systems, certain fluorite related ordered phases, namely, a rhombohedral phase with about 40 mol% of EuF3 or ErF3 in PbF2, and a tetragonal phase with 45-50 mol% of ErF3 in PbF2, are observed. In all the three systems, no solubility of the PbF2 in the hexagonal or orthorhombic rare-earth fluoride lattice is observed. This is the first report on phase relation in these three systems under short annealed and slow cooled condition. (C) 2004 Elsevier Inc. All rights reserved.