8. X-Ray Absorption Spectroscopy

Despite numerous investigations of lead zirconium titanate compounds, little information exists about the microscopic structure of the precursors in solution and their changes in course of the sol-gel process. This fact is not astonishing, since common methods of physical chemistry, like molecular weight determination, IR- and NMR-spectroscopy, conductivity measurements etc. do not provide direct information about the precursor structure. X-ray absorption spectroscopy, however, is a powerful method for studying local environment of metal atoms in liquid and amorphous materials. Nevertheless, this method was rarely applied to the study of the sol-gel process until the late nineties [Malic et al. (J Mater Res 12:2602, 1997)]. In this chapter, EXAFS spectroscopical investigations on the sol-gel-based systems, appropriate for thin film manufacturing via CSD, are presented. After a short introduction about the EXAFS method in theory and practice, we give an overview of the classical thin film compounds, namely the binary systems lead titanate (PT) and lead zirconate (PZ), the ternary lead zirconium titanate (PZT) and quaternary lead zirconium titanate, doped with lanthanum (PLZT). All these systems form ferroelectric perovskite-type films. Our overview will close with an outlook on investigations on new materials produced by CSD like the interesting new high-temperature superconductors (HTS).