In-Situ Transmission Electron Microscopy Crystallization Studies of Sol-Gel-Derived Barium Titanate Thin Films

• Published in: Journal of the American Ceramic Society 1997-11, Vol.80 (11), p.2828-2836
• Main Authors: Gust, Maria C., Evans, Neal D., Momoda, Leslie A., Mecartney, Martha L.
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Solid phase epitaxy; growth from solid phases
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1997.tb03200.x

Barium titanate (BaTiO3) thin films that were derived from methoxypropoxide precursors were deposited onto (100) Si, Pt/Ti/SiO2/(100) Si, and molecular‐beam‐epitaxy‐grown (MBE‐grown) (100) BaTiO3 on (100) Si substrates by spin coating. The crystallization behavior of the amorphous‐gel films was characterized using in‐situ transmission electron microscopy heating experiments, glancing‐angle X‐ray diffraction, and differential thermal analysis/thermogravimetric analysis. Amorphous‐gel films crystallized at a temperature of ∼600°C to an intermediate nanoscale (5–10 nm) barium titanium carbonate phase, presumably BaTiO2CO3, that subsequently transformed to nanocrystalline (20–60 nm) BaTiO3. Random nucleation in the bulk of the gel film was observed on all substrates. In addition, oriented growth of BaTiO3 was concurrently observed on MBE‐grown BaTiO3 on (100) Si. High‐temperature decomposition of the intermediate carbonate phase contributed to nanometer‐scale residual porosity in the films. High concentrations of water of hydrolysis inhibited the formation of the intermediate carbonate phase; however, these sols precipitated and were not suitable for spin coating.