A comparative study on Bi4Ti3O12 and Bi3.25La0.75Ti3O12 ferroelectric thin films derived by metal organic decomposition

Abstract

The crystal orientations and electrical properties of Bi4Ti3O12 (BIT) and Bi3.25La0.75Ti3O12 (BLT) ferroelectric thin films were studied and compared. Stoichiometric BIT and BLT samples were deposited on Pt(111) substrates and crystallized at 750 °C to get mixed orientations. The BIT sample exhibited a/b axes orientation with (117) component, while the BLT sample was more c-axis oriented. The 2Pr values of such BIT and BLT were 34.3 μC/cm2 and 25.7 μC/cm2, respectively. Nevertheless, BLT has much better leakage current and polarization saturation properties. In order to obtain c-axis oriented BIT thin films, excess bismuth was used. BIT with 15% excess bismuth processed at 750 °C was purely c-axis oriented and only possessed a 2Pr value of 4.9 μC/cm2, while that of 15% excess bismuth BLT sample was 18.3 μC/cm2. This can be attributed to the large polarization anisotropy in BIT, and this anisotropy is reduced by lanthanum doping.

Differences in nature of electrical conductions among Bi4Ti3O12-based ferroelectric polycrystalline ceramics

“…Isovalent substitution for Bi 3+ by lanthanoid cations (La 3+ , Pr 3+ , Nd 3+ , etc .) at the perovskite A site has been found to be an effective way to reduce V O •• and V Bi ′′′ concentrations in the perovskite layers 3, 21–23 . On the other hand, B-site donor substitution such as W 6+ , Nb 5+ or Ta 5+ , can significantly decrease the bulk conductivity and enhance ferroelectric and piezoelectric properties of the samples 11, 12, 24–27 .…”

Chemical solution growth of ferroelectric oxide thin films and nanostructures

“…4,5 Chemical deposition methods include chemical vapor deposition (CVD) and chemical solution deposition (CSD) methods such as sol-gel and metal-organic decomposition (MOD). 3,6 Molecular beam epitaxy is a combined chemical and physical deposition method that has proved successful in processing ferroelectric oxide thin films. CSD offers a number of advantages over other methods of thin film fabrication, including comparatively low capital investment costs, good homogeneity and thickness uniformity over a large area with minimal variations (r3%), 7 as well as enhanced compositional control.…”

Effect of Thickness on Ferroelectric Properties of Bi3.25La0.75Ti3O12 Thin Films

“…BIT thin films co-doped with Sm and Ta, denoted as BSTTO, exhibited markedly improved ferroelectric properties, boasting a higher remanent polarization (2P r = 46.2 µC/cm 2 ) compared to BIT thin films (2P r = 26 µC/cm 2 ) [21]. Various techniques, including pulsed laser deposition (PLD) [22], magnetron sputtering (MS) [23], metal-organic chemical vapor deposition (MOCVD) [24], and the sol-gel method [25], have been employed for the preparation of BLT ferroelectric thin films. Among these, the sol-gel process stands out for its cost-effectiveness, facile stoichiometry control, and uniform deposition over large areas, making it versatile for widespread applications.…”