A novel synthesis method of delafossite-type CuYO₂ using a layered yttrium hydroxide as an yttrium source

A facile synthesis method of delafossite-type CuYO₂ using a layered yttrium hydroxide (LYH) was developed. LYH microplates and Cu₂O nanoparticles were both prepared from aqueous solutions and used as raw materials for the solid-state reaction to form CuYO₂. It was found that CuYO₂ could be obtained by heating LYHCu₂O mixed powder at 900°C for 4 h under a N₂ atmosphere. Although the product contained a slight amount of Y₂O₃, the heating time used in the proposed method was much shorter than that required for the conventional synthesis method via the Cu₂Y₂O₅ precursor phase. Analysis of the X-ray diffraction pattern showed that the CuYO₂ powder synthesized using LYH contained the 3R-type polymorph as the major content, whereas a larger content of the 2H-type polymorph was included in the powder synthesized by the conventional method. Based on these results, a topotactic reaction maintaining the layered structure of LYH was proposed as the formation mechanism for CuYO₂ in LYHCu₂O mixed powder.