Recalculations of Madelung Potentials and Polarisabilities of Ions in Stoichiometric Rutile (TiO2)

Abstract

AbstractThe Madelung potentials in stoichiometric rutile (TiO2) are calculated and found to be 29.53 eV at the Ti4+ site and −41.20 eV at the O2‐ site. These potentials lead to the value of 141.5 eV for the Madelung energy per TiO2 “molecule” and also the value of 4.810 for the Madelung constant. Using the Madelung potential at the Ti4+ ion, the electronic polarisability of the Ti4+ ion is estimated to be 0.368 Å3. This result is used to determine the ionic polarisability of the Ti4+ ion and the electronic and ionic polarisabilities of the O2‐ ion. The electronic polarisability of the O2‐ ion is found to be large in value compared with that in other oxides. The possible connection between polarisability and defect structure formation in nonstoichiometric rutile is discussed.