Structural, morphological, and raman spectroscopic investigation of multiferroic (1-x) LaFeO₃-xBaTiO₃ Solid Solutions (0 ≤ x ≤ 0.3)

Abstract

• Solid solutions of (1−x)LaFeO₃–xBaTiO₃ (0 ≤ x ≤ 0.3) were successfully synthesized using the solid-state reaction method. • A structural phase transition from orthorhombic (Pbnm) to tetragonal (P4mm) symmetry was observed with increasing BaTiO₃ content. • Rietveld refinement revealed a biphasic region between x = 0.10 and x = 0.30, indicating the presence of a morphotropic phase boundary (MPB). • Dielectric measurements exhibited enhanced permittivity and relaxor behavior, especially at x = 0.3. • The diffuse phase transition and frequency-dependent dielectric peaks were attributed to cationic disorder and polar nanoregions (PNRs). • The optimized composition showed promising characteristics for multifunctional applications in dielectric and magnetoelectric devices. Solid solutions of (1-x)LaFeO₃-xBaTiO₃ (0 ≤ x ≤ 0.3) were synthesized using the conventional solid-state reaction method in order to investigate the effect of BaTiO₃ incorporation on structural, morphological, vibrational, and functional properties. X-ray diffraction (XRD) together with Rietveld refinement confirmed the formation of single-phase perovskite structures, showing a gradual transformation from the orthorhombic LaFeO₃ phase to the tetragonal BaTiO₃ phase as x increases, with a morphotropic phase boundary (MPB) identified at x = 0.3. Williamson–Hall analysis revealed an increase in crystallite size from approximately 125 to 138 nm along with a corresponding rise in microstrain, while electron density mapping evidenced a redistribution of charge density around Ba/Ti and La/Fe sites. Three-dimensional structural modeling (VESTA) illustrated the coexistence of orthorhombic and tetragonal phases in the intermediate composition range. Scanning electron microscopy (SEM) revealed dense microstructures and grain growth from about 1 μm (x = 0) to 4–6 μm (x = 0.3), associated with improved densification. Raman spectroscopy showed shifts in Fe–O and Ti–O vibrational modes, confirming lattice distortion and phase coexistence, while FTIR spectra confirmed the progressive formation of mixed phases. Dielectric measurements showed a significant enhancement of permittivity with BaTiO₃ addition, accompanied by relaxor-type behavior and a diffuse phase transition near Tₘ, with the highest εr (∼17 600) for x = 0.3. The optimal composition at x = 0.3 exhibited a favorable combination of ferroelectric and magnetic properties, indicating strong magnetoelectric coupling and high potential for multifunctional device applications.