First principles electronic and elastic properties of fresnoite Ba2TiSi2O8 (dataset)
Taylor, Ned; Davies, Francis; Hepplestone, Steven
Date: 22 November 2017
Dataset
Publisher
University of Exeter
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Abstract
Electronic, structural and elastic properties of fresnoite, Ba2TiSi2O8 (BTSO), are obtained via first
principles calculations. The electronic properties having been comparatively analysed using both
the generalised gradient approximation and the hybrid functional method. The indirect band gap
of BTSO is found to change significantly ...
Electronic, structural and elastic properties of fresnoite, Ba2TiSi2O8 (BTSO), are obtained via first
principles calculations. The electronic properties having been comparatively analysed using both
the generalised gradient approximation and the hybrid functional method. The indirect band gap
of BTSO is found to change significantly through the choice of functional; it shows an increase
from 3.79 eV to 5.72 eV. A small indirect gap of 0.33 eV is also present directly above the conduction
band edge, which allows for small optical transitions similar to that of defect transitions. The
titanium orbitals are dominant near the conduction band edge, with oxygen orbitals being the
main contributor to the valence band edge. Dielectric and elastic properties of the material are also
obtained, with the bulk modulus being 131.73 GPa and the elastic moduli along the [1 0 0] and [0 0 1]
directions being 180.57 GPa and 102.56 GPa, respectively. Theoretical values for Raman frequencies
are reported for BTSO. Finally, Bader charge analysis reveals the barium and titanium atoms in BTSO
are comparable to their charges in BaTiO3. However, due to the presence of the Si–O bonds, oxygen
exhibits a significant charge redistribution. Through the choice of functional, charge can become
more localised on the oxygen atoms.
Physics and Astronomy
Faculty of Environment, Science and Economy
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