Enhanced remnant polarization in ferroelectric Bi₆Fe₂Ti₃O₁₈ thin films

Abstract

For practical applications of ferroelectric memory, a large remnant polarization in nontoxic Pb-free ferroelectric materials is required. We prepared Bi 6 Fe 2 Ti 3 O 18 thin films on Pt/Ti/SiO 2 /Si (100) substrates by chemical solution deposition using different annealing processes and found that a well-defined ferroelectric hysteresis loop with a rather large remnant polarization (P r ≈ 21.5 μC cm −2 ) occurs in Bi 6 Fe 2 Ti 3 O 18 thin films prepared by rapid thermal annealing in air. This value of remnant polarization is superior to those of other ferroelectric Aurivillius compounds such as O 18 thin films prepared by chemical solution deposition and pulsed laser deposition. The results of X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and ferroelectric P-E hysteresis loops revealed that the grain size, surface morphologies, oxygen vacancies and lattice distortion play very important roles in the determination of the remnant polarization. The present study provides an effective route to prepare layered Aurivillius thin films with a large remnant polarization by chemical solution deposition.

Atomic Layer Deposition of Mixed-Layered Aurivillius Phase on TiO2 Nanotubes: Synthesis, Characterization and Photoelectrocatalytic Properties

“…The peaks' asymmetry indicates the presence of mixed valence of iron cations [44]. Oxygen vacancies will occur in the presence of Fe 2+ ions in the structure [45], which are necessary to maintain electroneutrality of the system, according to the Kröger-Vink notation:…”

Multiferroic properties of Bi0.5K0.5TiO3–BiFe1−xCoxO3 (0 ≤ x ≤ 0.2) solid solution

“…27 Previous results have demonstrated that the lattice distortion can also affect the ferroelectric polarization of the displacement ferroelectrics because of the crystal anisotropy of the ferroelectric phase in perovskite ferroelectrics such as Bi 6 Ti 3 Fe 2 O 18 , BiFeO 3 , PbTiO 3 and BaTiO 3 . [28][29][30][31] Therefore, the enhancement of ferroelectric polarization in the BKT-BFCO samples can be attributed to the combination of the lattice distortion and the increased grain size caused by Co doping.…”

Retention Characteristics of Five‐Layered Aurivillus Films With Large Polarization

“…The precursor solution used for the coating was prepared by dissolving appropriate amounts of high‐purity bismuth acetate, iron acetate, and tetrabutyl titanate in propanoic acid. Details of the solution preparation and coating have been reported previously . The thin film was spin‐coated at 6000 rpm for 20 s and then baked in a 400 °C preheated tube furnace for 10 min in air.…”