Inducing Crystal Phase Transformation of Titanium Oxide by Pulse Laser Irradiation

Abstract

To selectively pattern titanium oxide with desired properties, we report inducing crystal phase transformation from rutile TiO2 to γ/λ-Ti3O5 and corundum Ti2O3 by pulse laser irradiation. The crystal phase of the produced titanium oxide could be systematically controlled by laser fluence. This crystal phase transformation simultaneously increased the electrical conductivity with changing the electrical conduction mechanism from band conduction to variable-range hopping conduction. This report also proposes the mechanism of the crystal phase transformation. Comparing thermodynamic calculations and finite element simulations of the temperature rise due to laser irradiation showed that this phase transformation can be interpreted as a reduction reaction caused by laser heating. Our findings indicate that laser irradiation can spatially pattern various crystal phases of titanium oxides on a substrate, and this technique will enable the regioselective, fine, and highly productive fabrication process of titanium oxide-based electronic devices.