Correlation of octahedral distortion with vibrational and electronic properties of LaFe1-xTixO3 nanoparticles

Abstract

LaFeO3 is a multiferroic with multiple functionalities. It demonstrates room-temperature magnetism. A prime interest in this material is to introduce formidable ferroelectricity in LaFeO3 that may improve its functionalities with magnetoelectric properties. Ti4+ has a higher charge and smaller ionic radii. Such changes may modify bond lengths, bond angles, octahedral tilting and oxygen content. As a result, the nature of crystallinity can be modified. As a consequence, the electronic properties like the band gap, transport properties may get influenced. Titanate perovskites are known to be ferroelectric materials. Intending to strengthen the ferroelectric properties of a magnetic LaFeO3, this work investigates the structural, vibrational and electronic properties of LaFe1-xTixO3 (0 ≤ x ≤ 0.50). The novelty of this work is on an in-depth study of the bond lengths and bond angles correlated with BO6 octahedra and La8O6 cage distortion. Ti substitution affects the entire perovskite structure by introducing a vertical flattening of the BO6 octahedra as well as the La8O6 cage. The strong hybridization of Ti4+ with O2− may be responsible for such modifications. The locus of octahedral apical oxygen fluctuates, influencing the tilting angle of the BO6 octahedra. This may be a result of the nature of the substituted cations and the oxygen acceptability limit of the lattice. The phonon modes and their modification have been correlated. The transport properties are modified with an external magnetic field. © 2020 Elsevier B.V.