Role of Electron–Phonon Interaction in Phase Transition of Zr-Substituted BaTiO₃

The tetragonal to cubic phase transition in BaTiO3 is a critical phenomenon, as it marks the ferroelectric to paraelectric transition. This study investigates the effects of zirconium substitution on the vibrational mode and phase transition behavior of BaTiO3 crystal lattice through Raman spectroscopy. A series of Ba(Ti,Zr)O3 compositions were analyzed and the results indicate that Zr substitutions alter the phonon dynamics and reduce the Ti-site distortion. The Raman spectra of Ba(Ti,Zr)O3 compositions display distinctive features that correlate with the progression of the phase transition, highlighting the sensitivity of this technique to dopant-driven modifications of the local structure. Thus, this work highlights the potential of Raman spectroscopy as a powerful tool for probing structural transformations and provides a new understanding of the role of electron–phonon coupling-driven phase transition in Zr-substituted BaTiO3. The results are supported by the theoretical Fano formulation and calculation of Helmholtz free energy for Zr-substituted BaTiO3.