Structural evolution of the KTa_(0.6)Nb_(0.4)O3 alkoxide-based solutions: probing the transition metals local environment by X-ray absorption spectroscopy

摘要

The KTa_(0.6)Nb_(0.4)O3 sols for chemical solution deposition of thin films were prepared from potassium acetate and transition metal ethoxides by the 2-methoxy-ethanol based route. The local environment of both transition metals after reflux times 1, 4, 24, and 48 h, whereby. the crystallization behavior of the films was strongly affected, was monitored by extended X-ray absorption fine structure spectroscopy, at Ta L3 and Nb K edges. The Ta species existed in the sols as monomers, remaining stable even with prolonged reflux time. The Ta-O-K correlations were confirmed in all cases. In contrast, the Nb-alkoxide formed dimers, with a gradual formation of oligomeric species with prolonged refluxing. The Nb-O-K correlations were present after all reflux times. The number of K neighbours around Nb increased upon refluxing, saturating at 24 h.