Optical absorption and disorder in delafossites

We present compelling experimental results of the optical characteristics of transparent oxide CuGaO2 and related CuGa1-xFexO2 (with 0.00≤x≤0.05) alloys, whereby the forbidden electronic transitions for CuGaO2 become permissible in the presence of B-site (Ga sites) alloying with Fe. Our computational structural results imply a correlation between the global strain on the system and a decreased optical absorption edge. However, herein, we show that the relatively ordered CuGa1-xFexO2 (for 0.00≤x≤0.04) structures exhibit much weaker vis-absorption compared to the relatively disordered CuGa0.95Fe0.05O2.