Precursors for layer-structured perovskite thin films of SrBi2Ta2O9 (SBT) and SrBi2Nb2O9 (SBN) were prepared by the reactions of a strontium-bismuth double methoxyethoxide and tantalum or niobium methoxyethoxide in methoxyethanol, followed by partial hydrolysis. Several spectroscopic techniques, such as 1H-, 13C-, and 93Nb-NMR (nuclear magnetic resonance), and Fourier-transform infrared spectroscopy were used to analyze the arrangement of the metals and oxygen in the precursor molecules. The precursors contained Sr-O-M (where M is Ta or Nb) bonds (i.e., a strontium is connected to two MO6 octahedra) and Sr-O-Bi bonds with a bismuth atom bonded to the oxygens of the MO6 octahedron. The arrangement of metals and oxygens was considered to be similar to the layer-structured perovskite crystal sublattice. As a result, the sol-gel-derived SBT thin films crystallized, by rapid thermal annealing in an oxygen atmosphere below 550°C, and they exhibited preferred (115) orientation. The crystallinity improved and the crystallite size increased with temperature up to 700°C. In the case of SBN thin films, a low heating rate (2°C/min) was necessary for the control of the crystallographic (115) orientation, whereas a rate of 200°C/s (rapid thermal annealing) produced films that exhibited c-axis orientation. The (115) SBT thin film, heated to 700°C, exhibited improved ferroelectric properties.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of the American Ceramic Society|
|State||Published - Jul 1998|
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry