Effects of Substitutions of Titanium(IV) Ions by Iron(III) and Niobium(V) Ions on Phase Formation in Lanthanide-Containing Systems Comprising Layered Bismuth Titanate Ferrite

Phase formation in the series of Bi3Nd2Fe1 + yTi3 – 2yNbyO15 and Bi3Tb2Fe1 + yTi3 – 2yNbyO15 (y = 0.0–0.6 and Δy = 0.2) samples is studied. When Bi3Nd2Fe1 + yTi3 – 2yNbyO15 solid solutions (ss) are doped with niobium(V) ions, the formation of Bi3Nd2FeTi3O15 layered perovskite, a member of the Aurivillius phase family of general formula Am – 1Bi2BmO3m + 3 (m = 4), is not dominant in samples where y ≥ 0.2. Bi4Ti3O12 (m = 3) and NdFeO3 phases are formed in the course of phase interaction under the chosen conditions. With higher niobium(V) amounts, a Bi2Ti2O7-base pyrochlore ss phase is formed in the Bi3Tb2Fe1 + yTi3 – 2yNbyO15 multicomponent system. Dielectric spectroscopy shows that the phases in samples of both series where y > 0.0 undergo structural alterations associated with magnetic and electric ordering.