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 temperatures, and their stability limits at atmospheric pressure were determined. They are characterized by a monoclinic crystal lattice distortion. For the PbB1/23+Nb1/2O3 compound series with the isomorphous substitution B3+, graphs of average lattice parameters of the perovskite and pyrochlore phases, the change of the specific unit cell volume at the perovskite–pyrochlore transition, the temperature of maximum dielectric permittivity, and the temperature of structure anomalies as functions of the B3+ cation radius were constructed and are discussed.