SOL-GEL SYNTHESIS OF EPITAXIAL FILMS OF (SrBa)Bi 2 (Nb,Ta) 2 0 9 AND Bi4Ti 3 0 12 ON [100] SrTiO 3 JONATHAN S. MORRELL,* ZILING B. XUE,* ELIOT D. SPECHT,** and DAVID B. BEACH*** *Department of Chemistry, University of Tennessee, Knoxville, TN **Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN ***Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6197, beachdb@oml.gov ABSTRACT An all-alkoxide sol-gel process utilizing methoxyethoxide complexes in 2-methoxyethanol was used to prepare epitaxial films of SrBi 2 Nb 2 0 9 , SrBi 2 Ta 2 O 9 , BaBi 2 Nb 2 0 9 , BaBi 2 Ta 2 O 9 , and Bi 4 Ti 3 O 1 2 on [100] oriented SrTiO 3 single crystals. Films were prepared by spin coating strontium titanate substrates with partially hydrolyzed alkoxide solutions and firing in air at 850 'C for 20 minutes. Out-of-plane orientation was confirmed by 0-20 scans which showed only [002/] reflections. In- plane orientation was determined by pole figures and phi-scans about the [105] plane in the case of the (Sr,Ba)Bi 2 (Nb,Ta) 2 0 9 complexes and the [117] plane in the case of Bi 4 Ti 3 O0 2 . Lattice constants and full-width at half-maximum (fwhm) values for both in-plane and out-of-plane reflections are reported. INTRODUCTION Layered perovskites containing bismuth (Aurivillius compounds or Aurivillius phases, after B. Aurivillius' who first prepared these compounds in 1949) have attracted considerable attention from researchers engaged in work on non-volatile semiconductor memory because these materials have been shown to undergo more than 1012 polarization reversals using platinum electrodes without degradation. 2 These fatigue-free materials hold the promise of replacing main-memory in a variety of electronic applications. The growth of highly-oriented or epitaxial films is of special interest because of the highly anisotropic nature of the dielectric response of the materials. 3 For example, these materials are predicted to show ferroelectric behavior only in the a-b plane. Indeed, Desu and co-workers 4 have shown that c-axis oriented films show drastically reduced remnant polarization and coercive field compared to randomly oriented polycrystalline films. Deposition techniques used to prepare films of these materials include physical deposition methods such as sputtering 5 and pulsed laser ablation, 6 ' 7 and chemical methods such as chemical vapor deposition. 8 ' 9 All of these methods require vacuum processing, expensive equipment and skilled operators, and each technique has specific advantages and disadvantages. Another deposition technique which has recently become viable is the use of solution chemistry to produce precursor films which can then be annealed to produce films." 0 The advantages of using solution techniques are low capital cost of deposition equipment, great flexibility in coating technique (spin coating, dip 'coating or spraying), precise composition control and low temperature crystallization. This technique has been used primarily for electronic and optoelectronic materials such as lithium niobate and lead zirconium titanate.' 0 In the case of the Aurivillius compounds, most solution preparations have made use of metal containing soaps in an organic solvent. This technique is known as Metal- Organic Decomposition or MOD"and can produce films of excellent quality, but suffers from the drawbacks that the soaps have a high content of organic material which may lead to shrinkage and 271 Mat. Res. Soc. Symp. Proc. Vol. 495 © 1998 Materials Research Society