Preparation of Delafossite-Type CuYO2Films by Solution Method

The preparation of CuYO2 films on quartz glass substrates was carried out through the solution method using copper and yttrium nitrates as sources. Firstly, dip-coated films on the quartz glass substrates were annealed in air, and then annealed again under nitrogen flow. Continuous films were formed on the substrate surfaces. The films annealed in air at 900–950 °C were almost completely dominated by the Cu2Y2O5 phase, except for slight appearances of CuO and Y2O3. After annealing under nitrogen flow at 900–950 °C, the films were almost completely dominated by the CuYO2 phase, except for slight appearances of Cu2O and Y2O3. The slight appearances of the impurity phases are possibly related to slight variations in the concentration ratio of the copper source to the yttrium source within the dip-coated films. The nitrogen-annealed films, as well as bulk CuYO2, exhibited a green emission band owing to the Cu+ interconfiguration transition from 3d94s1 to 3d10 with the Stokes shift, being consistent with the dominant appearance of the CuYO2 phase.