The electronic structure of TiO2 has been extensively studied through a variety of experimental and computational methods. Its properties range from thin film photovoltaic cells to optics. TiO2 provides an excellent model to study computationally due to the wealth of experimental data and its inexpensive computational cost. Our hypothesis is that larger crystal radii of substituent atoms decrease the band gap of crystalline TiO2. Atoms of differing crystal radii and electronegativity were selected for substitution into three polymorphic forms of TiO2, which are rutile, anatase, and brookite. Our computational approach utilizes the linearized-augmented plane-wave approach of density functional theory in the WIEN2k computational software, and includes the incorporation of the modified Becke-Johnson potential, to determine the band gap and density of states for each case. Optimization protocols were performed on the TiO2 polymorphs, and resulted in band gap values of 2.5 eV, 2.9 eV, and 3.0 eV for rutile, anatase, and brookite respectively. These optimized results compared well with experimental values and the optimized unit cells will be used to generate 48 atom supercells for the aforementioned substitution studies.

Impact of substituent size and electronegativity on the band gap of TiO2 polymorphs

249th National Meeting (2015)

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