Computational Chemistry Meets Experiments for Explaining the Geometry, Electronic Structure, and Optical Properties...

In this paper, we present a combined experimental and theoretical study to disclose, for the first time, the structural, electronic, and optical properties of Ca₁₀V₆O₂₅ crystals. The microwave-assisted hydrothermal (MAH) method has been employed to synthesize these crystals with different morphologies, within a short reaction time at 120 °C. First-principle quantum mechanical calculations have been performed at the density functional theory level to obtain the geometry and electronic properties of Ca₁₀V₆O₂₅ crystal in the fundamental and excited electronic states (singlet and triplet). These results, combined with the measurements of X-ray diffraction (XRD) and Rietveld refinements, confirm that the building blocks lattice of the Ca₁₀V₆O₂₅ crystals consist of three types of distorted 6-fold coordination [CaO₆] clusters: octahedral, prism and pentagonal pyramidal, and distorted tetrahedral [VO₄] clusters. Theoretical and experimental results on the structure and vibrational frequencies are in agreement. Thus, it was possible to assign the Raman modes for the Ca₁₀V₆O₂₅ superstructure, which will allow us to show the structure of the unit cell of the material, as well as the coordination of the Ca and V atoms. This also allowed us to understand the charge transfer process that happens in the singlet state (s) and the excited states, singlet (s*) and triplet (t*), generating the photoluminescence emissions of the Ca₁₀V₆O₂₅ crystals.