TY - JOUR
T1 - Ab-initio calculations of the optical band gap of TiO2 thin films
AU - Wunderlich, Wilfried
AU - Miao, Lei
AU - Tanemura, Masaki
AU - Tanemura, Sakae
AU - Jin, Ping
AU - Kaneko, Kenji
AU - Terai, Asuka
AU - Nabatova-Gabin, Nataliya
AU - Belkada, Rachid
PY - 2004
Y1 - 2004
N2 - Titanium dioxide has been extensively studied in recent decades for its important photocatalytic application in environmental purification. The search for a method to narrow the optical band gap of TiO2 plays a key role for enhancing its photocatalytic application. The optical band gap of epitaxial rutile and anatase TiO2 thin films deposited by helicon magnetron sputtering on sapphire and on SrTiO3 substrates was correlated to the lattice constants. The optical band gap of 3.03 eV for bulk-rutile increased for the thin films to 3.37 on sapphire. The band gap of 3.20 eV for bulk-anatase increases to 3.51 on SrTiO3. In order to interpret this expansion, ab-initio calculations were performed using the Vienna ab-initio software. The calculations for rutile as well anatase show an almost linear increase of the band gap width with decreasing volume or increasing lattice constant a. The calculated band gap fits well with the experimental values. The conclusion from these calculations is, in order to achieve a smaller band gap for both, rutile or anatase, the lattice constant c has to be compressed, and a has to be expanded.
AB - Titanium dioxide has been extensively studied in recent decades for its important photocatalytic application in environmental purification. The search for a method to narrow the optical band gap of TiO2 plays a key role for enhancing its photocatalytic application. The optical band gap of epitaxial rutile and anatase TiO2 thin films deposited by helicon magnetron sputtering on sapphire and on SrTiO3 substrates was correlated to the lattice constants. The optical band gap of 3.03 eV for bulk-rutile increased for the thin films to 3.37 on sapphire. The band gap of 3.20 eV for bulk-anatase increases to 3.51 on SrTiO3. In order to interpret this expansion, ab-initio calculations were performed using the Vienna ab-initio software. The calculations for rutile as well anatase show an almost linear increase of the band gap width with decreasing volume or increasing lattice constant a. The calculated band gap fits well with the experimental values. The conclusion from these calculations is, in order to achieve a smaller band gap for both, rutile or anatase, the lattice constant c has to be compressed, and a has to be expanded.
KW - Anatase
KW - Density of states
KW - Epitaxial growth
KW - Rutile
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U2 - 10.1142/s0219581x04002231
DO - 10.1142/s0219581x04002231
M3 - Article
AN - SCOPUS:10644287726
VL - 3
SP - 439
EP - 445
JO - International Journal of Nanoscience
JF - International Journal of Nanoscience
SN - 0219-581X
IS - 4-5
ER -