Sol-gel synthesis and multiferroic properties of pyrochlore-free Pb(Fe0.5Nb0.5)O3 thin films

IMHOFF, L.; DI MARCO, M.B.; BAROLIN, S.A.; RENGIFO, M.A.; AGUIRRE, M.H.; STACHIOTTI, M.G.

CERAMICS INTERNATIONAL

ELSEVIER SCI LTD

Año: 2024 vol. 50 p. 5746 - 5754

0272-8842

Lead iron niobate (PbFe0.5Nb0.5O3 – PFN) thin films were synthesized by a modified sol-gel route, which offers the advantage of a rapid, simple and non-toxic reaction method. Polycrystalline perovskite-structured PFN thin films without pyrochlore phases were obtained on Pt/Ti/SiO2/Si substrates after sintering by rapid thermal annealing at 650 °C. TEM and AFM images confirmed the excellent quality of the sintered film, while EDS spectroscopy revealed the presence of oxygen vacancies near the film/substrate interface. Electric measurements show good dielectric properties and ferroelectric behavior, characterized by typical C–V curves and well-defined P-E ferroelectric loops at 1 kHz, with remanent polarization values of ∼12 μC/cm2. The polarization, however, increases with decreasing frequency, indicating the presence of leakage currents. I–V measurements show a significant increase in DC-conduction at relatively low fields (around 100 kV/cm). The films display ferromagnetic behavior at room temperature, with magnetic remanence around 30 emu/cm3 and a coercive field of 1 kOe. These values are significantly higher than those obtained for PFN powders fabricated by the same sol-gel route, as well as the magnetization values reported in the literature for epitaxial films.