Structural regularities and dielectric phenomena in the compound series PbB1/23+Nb1/2O3

The metastable perovskite phases of the compounds PbB1/23+Nb1/2O3 (B3+ = Er , Tb, Gd, Eu, Sm) were first obtained under high pressures at high temperat ures, and their stability limits at atmospheric pressure were determined. T hey are characterized by a monoclinic crystal lattice distortion. For the P bB1/23+Nb1/2O3 compound series with the isomorphous substitution B3+, graph s of average lattice parameters of the perovskite and pyrochlore phases, th e change of the specific unit cell volume at the perovskite-pyrochlore tran sition, the temperature of maximum dielectric permittivity, and the tempera ture of structure anomalies as functions of the B3+ cation radius were cons tructed and are discussed. (C) 2000 Elsevier Science Ltd. All rights reserv ed.