Electronic structure, optical and Mössbauer investigations of ferroelectric [Pb(Fe0.5Nb0.5)O3]0.2-[(Ca0.2Sr0.8)TiO3]0.8

Abstract

In this research article, we report the various functional properties of [Pb(Fe_0.5Nb_0.5)O₃]_0.2- [(Ca_0.2Sr_0.8)TiO₃]_0.8 perovskite ceramic compound prepared by the solid-state process. Rietveld refinement proved that the compound crystallises in a pseudocubic structure as the primary phase. The dual oxidation states of Fe, Nb, Ti and the presence of oxygen vacancies were analysed by X-ray photoelectron spectroscopy. Ti–O and Ti–O–Ti prominent perovskite vibrations were examined by Fourier transform infrared (FTIR) analysis. Raman spectroscopy technique was employed to study the asymmetric TiO₆ octahedral stretching and A_1g phonon mode of PbFe_0.5Nb_0.5O₃ (PFN). Field emission scanning electron microscopy (FESEM) predicted better grain growth with an average grain size of 2.445 µm. Energy-dispersive X-ray spectroscopy (EDS) analysis was done for elemental confirmation and purity of the sample. A detailed optical analysis was done by incorporating both absorbance and diffuse reflectance spectroscopy. A narrow band gap was revealed from the optical studies and Urbach energy was analysed. The conduction band minimum (CBM) level was estimated to be − 1.14 eV exploring the photocatalytic response. Electrical properties were investigated in terms of dielectric constant, conductivity, complex impedance and modulus analyses. A weak ferroelectric response was noticed with the remnant polarisation of 0.181 µC\(/\)cm² from P–E loop analysis. Mössbauer spectroscopy revealed a strong paramagnetic doublet indicating the high-spin Fe³⁺ species in the octahedral environment.