Insights into Polarized Raman, Infrared, and Dielectric Spectra of Lead-Free (Na0.5Bi0.5)ZrO3 : A Density Functional Theoretical Investigation

Abstract

In this work, we present a DFT based first principle theoretical investigation of lattice dynamics, electronic structure, and dielectric properties of room temperature phase of Na0.5Bi0.5ZrO3 (NBZ) system. In particular, theoretical and experimental Raman studies of the system are performed and the symmetry labels of NBZ vibrational modes are assigned. In addition, theoretical polarized Raman spectra, Born-effective charge tensors, Infrared (IR) reflectivity, oscillator strengths etc. are obtained and analysed. The experimental bandgap energy is obtained using UV–Vis spectroscopy. Experimental Raman spectra at room temperature are recorded. The experimental and computed Raman spectrum shows good agreement with each other. The Raman mode intensities are computed for different light polarization configurations suggest the presence of different symmetry modes for each polarization setup. The electronic band structure and density of states of NBZ are investigated, and optical absorption spectrum is also determined. Moreover, we explored the effectiveness of DFT semi-local, hybrid and meta-GGA exchange-correlations (XC) functionals as well as the impact of spin-orbit coupling (SOC), on electronic band gap estimations. The electron localization function, COHPs and Bader charge analysis are also carried out to determine the bonding nature in the NBZ compound. In summary, our work presents important benchmark insights on NBZ, that were not reported before.