Fe-doped titanite pigment: Synthesis, DFT/TDDFT calculations by Lanczos and Bethe-Salpeter equation methods and comparison of computational and experimental color properties

Abstract

In this paper, titanite (CaTiSiO5) and Fe-doped titanite structures were synthesized by the conventional ceramic route. DFT/TDDFT calculations on these structures were performed by Quantum ESPRESSO package and YAMBO code. For DFT/TDDFT calculations, titanite structure was modeled with 32 atoms and Fe atoms were used as dopants in titanite structure. The electronic properties of the structures were calculated. It shows that the band gap of the Fe-doped titanite structures decreases with increasing iron concentration. For the TDDFT calculations, two methods were used named Lanczos and Bethe-Salpeter equation (BSE) methods. The optical properties and colorimetric results of the experimental and computational samples were compared. The optical properties showed that the colorimetric results of the experimental and computational samples for the BSE method were equivalence (unlike the Lanczos method). Also, calculations showed that the position of the iron in the titanite structure affects the absorption spectra and the colorimetric results.