Effects of structure ordering, structure defects and external conditions on properties of complex ferroelectric perovskites

Structural rearrangements in lead-containing (A′A″) (B′B″)O₃ type perovskite compounds are caused by technological treatment, high-energy radiation and ambient conditions. Variation of structure ordering along with modification (substituted or defected solid solutions) may provide promising compositions for applications, e.g., cascade microcryogenic devices (PST solid solutions); efficient piezoelectric materials - here the new (1-x)Pb(Lu_1/2Nb_1/2)O₃-xPbTiO₃ system in the morphotropic region. The maximum values of the electromechanical coupling coefficients k_p = 0.663, k_t = 0.481, k₃₁ = 0.355 were attained in compositions PLuNT 59/41 (T_m = 353 °C) near the morphotropic phase boundary. In P(L)ZT and PLT thin films asymmetry of piezoelectric coefficient d₃₃ hysteresis diminished values of d₃₃ and their frequency dependence were attributed to residual stress at the film-substrate/electrode interfaces and unrelaxed strain characteristic in highly oriented thin films. Neutron irradiation by fluence 10¹⁸n/cm² causes some changes in thin film properties, however, they are less pronounced compared to bulk material of the same composition.