Tuning colors in Zr-based thin film metallic glasses

In this work, a novel approach for the preparation of a variety of colored thin film metallic glasses (TFMGs) is proposed. Based on magnetron sputtering technique using a mixture of nitrogen and argon as the sputtering gas, ZrCuFeAlAg TFMGs with a high hardness of 8.9 GPa and a variety of colors ranging from yellow to aqua to pink to purple were achieved by adjusting the nitrogen-doping content and the thickness of the thin films. It was revealed that the change of colors of the TFMGs is governed by a two-step mechanism: i) the TFMGs first became partially transparent by nitrogen doping owing to the formation of amorphous ZrxNy nitrides, which led to expansion of the energy band gap of the films, and ii) the color was varied by changing the thickness of the film due to the interference effect. The present work presents the possibility of making functional TFMGs for optical and electrical device applications.