Study of structural, and optical properties of the layered perovskite La2Ti2O7 nanoparticle

Abstract Nanocrystalline of La2Ti2O7 denoted by LTO is prepared by the sol–gel method in order to investigate their structural and optical properties. X-ray diffraction (XRD) confirmed the complete crystallization of calcined sample at 1050 °C for 3 h. The results display a single-phase as a layered perovskite-type in a monoclinic structure with space group P21. The optical properties were investigated at room temperature by an UV–visible (UV–vis) spectrophotometer. The UV–vis spectrum indicated that the studied powder has an optical bandgap of 3.69 eV. Ab-initio calculations were performed to study the electronic structure using generalized gradient approximation (GGA) and the modified Becke-Jonson (mBJ) to correct the gap energy. The obtained gap energy using GGA is of 2.95 eV, which is far from the value 3.69 eV obtained experimentally and indicating that in this case, GGA approximation underestimates the gap energy. Whereas, the obtained energy using the GGA+mBJ approximation is of 3.64 eV, which is in good agreement to the experimental one.