Polarized Raman, infrared and dielectric spectra of lead-free K0.5Na0.5NbO3piezoelectric system: insights fromab-initiotheoretical and experimental studies.
J Phys Condens Matter
; 36(42)2024 Jul 22.
Article
en En
| MEDLINE
| ID: mdl-38986476
ABSTRACT
The K0.5Na0.5NbO3(KNN) system has emerged as one of the most promising lead-free piezoelectric over the years. In this work, we perform a comprehensive investigation of electronic structure, lattice dynamics and dielectric properties of room temperature phase of KNN by combiningab-initioDFT based theoretical analysis and experimental characterization. We assign the symmetry labels to KNN vibrational modes and obtainab-initiopolarized Raman spectra, Infrared reflectivity, Born-effective charge tensors, oscillator strengths etc. The KNN ceramic samples are prepared using conventional solid-state method and Raman and UV-Vis diffuse reflectance spectra are obtained. The computed Raman spectrum is found to agree well with the experimental spectrum. In particular, the results suggest that the mode in range â¼840-870 cm-1reported in the experimental studies is longitudinal optical withA1symmetry. The Raman mode intensities are calculated for different light polarization set-ups that suggests the observation of different symmetry modes in different polarization set-ups. The electronic structure of KNN is investigated and optical absorption spectrum is obtained. Further, the performances of DFT semi-local, meta-GGA and hybrid exchange-correlations functionals, in the estimation of KNN band gaps are investigated. The KNN bandgap computed using GGA-1/2 and HSE06 hybrid functional schemes are found to be in excellent agreement with the experimental value. The COHP, electron localization function and Bader charge analysis is also performed to deduce the nature of chemical bonding in the KNN. Overall, our study provides several bench-mark important results on KNN that have not been reported so far.
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Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
J Phys Condens Matter
Asunto de la revista:
BIOFISICA
Año:
2024
Tipo del documento:
Article
País de afiliación:
India
Pais de publicación:
Reino Unido