Improvement of Solid Through Improved Solutions and Gels (1): Utilization of Reduction Agent and Reduced Atmosphere

Abstract

In Sect. 12.1, a novel low-temperature crystallization path for perovskite lead zirconate titanate (PZT) from solution is reported. The modification of a PZT solution with monoethanolamine (MEA) resulted in a change in the crystallization behavior. MEA was strongly coordinated to the metal ions, resulting in reduction of Pb2+ into Pb0 because of a reducing environment at 200–300 °C. Nanoscopic separations of Pb0 were later transformed into uniformly distributed PbO nanocrystals and clusters in the amorphous Zr/Ti–O matrix and finally crystallized into perovskite at 400–500 °C. On the other hand, pyrochlore phase appeared in the conventional crystallization process. The avoidance of pyrochlore formation is a key for the low-temperature crystallization of perovskite. X-ray absorption fine structure (XAFS) analysis was performed to reveal the structures in solutions and amorphous phases.