EXAFS Study of Amorphous Precursors for Pb(Zr,Ti)O3 Ceramics

In as-hydrolyzed amorphous precursors of Pb(Zr,Ti)O₃ (PZT) ceramics with various Zr/Ti ratios prepared from lead acetate and transition metal n-butoxides in parent alcohol medium the local environment of constituent metal atoms has been determined by EXAFS. The local zirconium atom environment in high-Zr precursors consists of distorted octahedra of oxygen atoms with all the bonds made up of Zr–O–Zr links. For low-Zr precursors a smaller distortion of the oxygen octahedra is observed, and two Ti atoms are found in the second shell. The titanium local environment is almost independent of the Zr/Ti ratio, with five oxygen atoms in the first and two titanium atoms in the second shell of neighbors. Lead atoms contain two oxygen atoms in the first coordination shell. Pb–O–M (M = Zr, Ti) links are identified in all precursors: the former at Zr/Ti 75/25 and the latter at lower Zr/Ti ratios. Although a pronounced tendency for the homocondensation of zirconium species is found down to a Zr/Ti 50/50 ratio, heterometallic links (Pb–O–M) are determined in PZT precursors.