Control of luminescence and conductivity of delafossite-type CuYO2 by substitution of rare earth cation (Eu, Tb) and/or Ca cation for Y cation Original Research Article

Delafossite-type oxides of CuTbyY1−yO2, CuEuyY1−yO2, CuCaxTbyY1−x−yO2 and CuCaxEuyY1−x−yO2 have been prepared by solid state reactions. The lattice-parameter dependence on the composition implies substitution of the Tb3+, Eu3+ and Ca2+ cations for the Y3+ site. Noticeable sharp emission lines due to the f–f transitions (5D4→7FJ, J=3–6) of Tb3+ or due to the f–f transitions (5D0→7FJ, J=0–4) of Eu3+ are observed at room temperature. Electrical conductivities of CuCaxTbyY1−x−yO2 and CuCaxEuyY1−x−yO2 are larger than those of CuTbyY1−yO2 and CuEuyY1−yO2, indicating the increase of the hole concentration caused by the substitution of Ca2+ for the Y3+ site. These results indicate the controllability of the luminescence and conductivity in CuCaxTbyY1−x−yO2 and CuCaxEuyY1−x−yO2 delafossite-type oxides by simultaneous substitution of the rare earth Tb3+ or Eu3+ cation and the Ca2+ cation for the Y3+ site.