Abstract
Precursors for layer-structured perovskite thin films of Sr2Bi2Ta3O12.5 or SBT223, and Sr2Bi2Nb3O12.5 or SBN223 were prepared by the reactions of Sr-Bi (2 : 2) double methoxyethoxide and Ta or Nb methoxyethoxide, followed by partial hydrolysis. By several analytical techniques, such as 1H-, 13C- and 93Nb-NMR (nuclear magnetic resonance) and FT-IR (Fourier transform infrared) the molecular structure of the precursors was found to be similar to the layer-structured perovskite crystal sub-lattice. As a result, the onset of crystallization in the sol-gel derived SBT223 thin films was at a low temperature of 550°C. By rapid thermal annealing in an oxygen atmosphere, the single-phase perovskite films exhibited preferred (1 1 7) orientation. In contrast to the SBT system, the observed number of the pseudo-perovskite layers of TaO6 octahedral units between Bi2O 2 2 + layers in the SBT223 was three. Despite the elongation of the unit cell along the c-axis, 700°C-heated SBT223 thin film did not exhibit a saturated hysteresis loop due to the small crystallite size.
Published Version
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