Mapping the transient phase diagram of titanium suboxide (TiO_x) thin films

Titanium suboxide (TiOx) thin films are incredibly versatile materials for applications in energy, sensing, and electronics, yet precise control of structure and chemistry in highly uniform thin films remains challenging. This work demonstrates a versatile, high-throughput method for the synthesis of titanium suboxide thin films using local, continuous wave (CW) laser induced oxidation. By systematically varying the laser power and exposure time, over 1200 unique temperature-time processing conditions were generated, converting a titanium metal film into an array of different TiO_x phases and compositions. Synchrotron micro-XRD, Raman spectroscopy, and UV–Vis–NIR characterization data were included in multi-modal analysis of the synthesized materials, and 10 unique phases were detected across the laser processing phase space: Ti, Ti₂O, TiO, Ti₂O₃, γ-Ti₃O₅, α/β-Ti₃O₅, Ti₄O₇, Ti₅O₉, rutile TiO₂, and black TiO₂. The collective datasets resulted in the construction of a transient phase diagram for oxidation of titanium which can serve as a guide for achieving desired properties of interest. This work illustrates the transformative potential of laser processing for the controlled synthesis of metastable suboxide materials, which can be patterned on a single substrate for advanced device fabrication.