Perovskite phase formation in pure and Sm- and La-substituted BiFeO3 thin films in isothermal and non-isothermal regimes

• Published in: Physical chemistry chemical physics : PCCP Vol. 27; no. 15; pp. 7665 - 7674
• Main Authors: Teixeira, M A M, Minussi, F B, Eiras, J A, Araújo, E B
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 09.04.2025
• Subjects: Bismuth; Bismuth ferrite; Kinetics; Lanthanum; Multiferroic materials; Perovskites; Rare earth elements; Samarium; Stoichiometry; Substitutes; Thin films
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d5cp00323g

The prototype bismuth ferrite (BiFeO3) has been considered a promising multiferroic material for next-generation devices due to its singular features. Still, several critical challenges that have not yet been overcome prevent its full implementation in commercial technologies. The kinetics of BiFeO3 phase growth in thin films and the effects of trivalent rare earth substitution on the dynamics of phase formation in this system are among the important subjects to be studied. The present work reports a study on the phase formation kinetics in pure BiFeO3, samarium-substituted BiFeO3 (Bi0.9Sm0.1FeO3), and lanthanum-substituted BiFeO3 (Bi0.9La0.1FeO3) thin films in isothermal and non-isothermal regimes using X-ray diffraction as an investigative tool. Pure BiFeO3 was the first system to form the perovskite phase, followed by Sm-BiFeO3 and La-BiFeO3 films, indicating that the rare-earth cations influence the perovskite formation, and La3+ is the most effective at delaying the phase formation. The perovskite phase fractions formed as a function of the temperature of different samples were fitted using fourteen appropriate theoretical kinetic models. The data from the pure BiFeO3 films were best fitted with the second-order model, while the third-order model resulted in better fits for the Sm- and La-substituted thin films. The activation energies determined through the Arrhenius relation were the lowest for pure BiFeO3 films and the highest for La–BiFeO3 films. The obtained results indicate that the transition of kinetic models along the system is due to the stoichiometry around the concentrations of the compound used in the synthesis.