**11. Conclusion**

In this chapter, we have described the most common structures of the cuprate materials, and the chemical reaction used to obtain it, especially the topotactic reaction. The cuprate materials with the general formula Ln2CuO4 were used particularly in the superconductivity field, but later, the materials have been successfully used in other applications as semiconductors or as anionic conductors, respectively. Thus, the cuprate of the formula Ln2CuO4 could be applied in photolysis, photoluminescence, fuel cells, and as dielectric materials.
