A polyethylene glycol-assisted route to synthesize Pb(Ni_1/3Nb_2/3)O₃-PbTiO₃ in pure perovskite phase

Ferroelectric relaxors (1 - x)Pb(Ni1/3Nb2/3)O3-xPbTiO3 (PNN-PT) with a composition (x = 0.36) near the morphotropic phase boundary (MPB) were prepared by a polyethylene glycol (PEG)-assisted solid-state reaction route. PEG with a molecular weight of 200 was introduced during the ball milling process of the raw oxide powders. XRD and TG/DSC results demonstrated that the interaction between PbO and PEG favors the transformation of lead-rich pyrochlore to lead-deficient pyrochlore, thus facilitating the formation of perovskite phase. Consequently, pure perovskite powders were synthesized at a relatively low temperature of 850 °C. Ceramics fabricated with the PEG-assisted route show a room temperature dielectric constant of 4987 and a maximum dielectric constant (at Tmax) of 24,307 at a frequency of 1 kHz. The piezoelectric constant d33 measured was 460 pC/N.