Influence of Fe substitution on the structural and optical properties of Gd2TiO5 ceramic

Abstract

The structural, optical, and electronic structure of Gd2TiO5 have been investigated and the effect of Fe substitution at Ti-site in rarely observed square pyramidal geometry of Ti-O5 polyhedron has been studied. For this purpose, the samples having the composition of Gd2Ti1−xFexO5 (x = 0.05, 0.07, and 0.10) were synthesized via the conventional solid-state reaction route. X-ray diffraction and Rietveld refinement confirmed the orthorhombic phase of synthesized samples with the Pnam space group. The variation of lattice parameters and bond lengths was studied as a function of Fe substitution. To investigate the optical characteristics further, optical absorption measurements have been carried out using diffuse reflectance spectroscopy, where the optical band gap (Eg) shows the systematic trend to the Fe substitution which can be related to the changes in the Ti/Fe–O bond length indicating that Ti/Fe–O bond length is playing the major role in tuning the band gap properties of these materials. To support the results, first-principles calculations were carried out using Quantum Espresso, confirming that Ti-3d and O-2p orbitals play a dominant role in defining the optical band gap in these materials. Hence, the optical, and electronic properties of these rare-earth titanates can be modulated by changing the orbital overlap and substituting the dopant element at the Ti-site. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.