Ferroelectric properties of La and Zr substituted Bi4Ti3O12 thin films

Abstract

Thin films of A-site substituted, B-site substituted, and both A- and B-sites cosubstituted Bi4Ti3O12 (BTO) by La3+ and Zr4+, i.e., Bi3.25La0.75Ti3O12 (BLT), Bi4Ti2.8Zr0.2O12 (BTZ), and Bi3.25La0.75Ti2.8Zr0.2O12 (BLTZ), were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. Structures of the films are investigated by x-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Compared to the well known BLT films, both the BTZ and BLTZ films have larger remanent polarization (Pr) but smaller coercive field (Ec). It is shown experimentally that the oxygen vacancy is the predominant factor determining ferroelectric fatigue. The effects of substitution on structural and ferroelectric properties of BTO are discussed in detail. As a result, the A- and B-sites cosubstitution might be one of the promising ways to improve ferroelectric properties of BTO.

Electrical studies on Zr-modified Bi3.25La0.75Ti3O12: a promising FRAM ceramic

“…[9] In addition, the title composition has shown great potential applications in memory devices. A lot of research work was reported by Zhang et al, [10] prepared in thin-film form.…”

Suppression of oxygen diffusion by thin Al2O3 films grown on SrTiO3 studied using a monoenergetic positron beam

“…1 Some metal oxides, such as barium strontium titanate and bismuth titanate, have also been studied for nonvolatile ferroelectric random access memory applications. 4,5 It is now recognized that oxygen vacancies in metal oxides play an important role in degrading the leakage characteristics of devices. During device fabrication processes, however, oxygen vacancies are often easily introduced into metal oxides through silicidation, desorption, silicate formation, and other phenomena.…”

Improving the Electrical Properties of Zr-Doped Bi3.15Nd0.85Ti3O12 Thin Films by Engineering Polarization Rotation

“…A change in lattice parameters is expected upon substitution of Zr 4+ for Ti 4+ ion, because the ionic radius of Zr 4+ (r Zr = 0.72 Å ) is approximately 18% larger than that of Ti 4+ (r Ti = 0.605 Å ). 21 Greater change in lattice parameters leads to further octahedral distortion. Table I summarizes the lattice parameters calculated based on Bi 4 Ti 3 O 12 (parent compound).…”