Structural investigations, band gap narrowing and magnetic characteristics of multiferroic [Pb(Fe0.5Nb0.5)O3]0.4 - [(Ca0.2Sr0.8)TiO3]0.6

Abstract We report a detailed and systematic investigation of the multifunctional properties of calcium strontium titanate [(Ca0.2Sr0.8)TiO3] substituted lead iron niobate [Pb(Fe0.5Nb0.5)O3] ceramic oxide manufactured by the effective high temperature solid state reaction method. Rietveld studies reveal the single phase formation of compound with a pseudocubic structure. The Williamson-Hall (W-H) analysis predicts the presence of tensile strain. Different molecular vibrations were detected using the Fourier transform infrared (FTIR) analysis. The local structures and optical modes were analyzed using Raman spectroscopy technique. The microstructural analysis had been done by field emission gun scanning electron microscope (FESEM). Energy dispersive X-ray spectroscopy (EDS) analysis was performed to check the purity. The detailed chemical structure and oxidation states were analyzed by incorporating the efficient X-ray photoelectron spectroscopy (XPS) technique. In addition to the valence identifications, the presence of oxygen vacancies was evident from the XPS analysis. The optical band gap and Urbach energy were analyzed by UV-Visible spectroscopy analysis. Effect of structural distortions, oxygen vacancies and electro-negativity on band gap were discussed. The photocatalytic response was studied by using Mulliken’s model. The electrical properties were analyzed in the frameworks of dielectric constant, tan δ, complex impedance spectroscopy and conductivity studies. The Jonscher’s law analysis revealed the presence of correlated barrier hopping (CBH) conduction mechanism. The binding energy (Wm), minimum hopping length (Rmin) and density of states near Fermi level (N(EF)) were analyzed. The ferroelectricity was studied by room temperature P-E loop. The magnetic study was performed by means of the room temperature M-H loop. The detailed magnetic structure of Fe nuclei was analyzed by incorporating the room temperature 57Fe Mössbauer spectroscopy.