Structural, electronic and elastic properties of potassium hexatitanate crystal from first-principles calculations

The structural, electronic and elastic properties of potassium hexatitanate (K2Ti6O13) whisker were investigated using first-principles calculations. The calculated cell parameters of K2Ti6O13 including lattice constants and atomic positions are in good agreement with the experimental data. The obtained formation enthalpy (−61.1535 eV/atom) and cohesive energy (−137.4502 eV/atom) are both negative, showing its high structural stability. Further analysis of the electronic structures shows that the potassium hexatitanate is a wide-band semiconductor. Within K2Ti6O13 crystal, the TiO bonding interactions are stronger than that of KO, while no apparent KTi bonding interactions can be observed. The structural stability of K2Ti6O13 was closely associated with the covalent bond interactions between Ti (d) and O (p) orbits. Further calculations on elastic properties show that K2Ti6O13 is a high stiffness and brittle material with small anisotropy in shear and compression.