Activation energies for crystallization of manganese-doped (K,Na)NbO3 thin films deposited from a chemical solution

Potassium sodium niobate (KNN) thin films are potentially useful for energy harvesting devices and for lead-free piezoelectric microelectromechanical systems. This work reports the activation energies for nucleation, growth and perovskite phase transformation from a 0.5% manganese-doped KNN 2-methoxyethanol-based solution modified with acetylacetone and excess alkali precursors. The films were annealed in a rapid thermal processor (RTP) with a hold step at temperatures from 500 to 550 degrees C. The activation energies for perovskite transformation and growth, determined by electron micrograph observation, were 687 +/- 13 and 194 +/- 10 kJ/mol. The activation energy for nucleation was 341 +/- 20 kJ/mol. Based on these data, crystallization in KNN is found to be nucleation-limited; thus, it should be possible to reduce the crystallization temperature by utilizing a seed layer which provides nucleation sites, provided the organics are removed from the film.

Automated summary

This study investigates the activation energies for KNN thin films with manganese doping, revealing that crystallization is nucleation-limited and can be reduced by using a seed layer.