Development of Conductive Delafossite-type Oxide Phosphor Co-doped with Rare-earth and Acceptor Cations

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Delafossite-type oxides of CuR_xY_(1-x) O_2 and CuR_xLa_(1-x) O_2 (R: Eu, Tb, Tm) samples were prepared by the conventional solid state reactions using binary oxides as sources. Taking account of the rare-earth ionic radii, the lattice-constant dependence on the concentration of the rare-earth cation implied doping with the R^(3+) cation on the Y^(3+) or La^(3+) site. A broad emission band due to the Cu^+ interconfiguration transition from 3d^94s to 3d^(10) was observed in CuYO_2 and CuLaO_2, while noticeable sharp emission lines due to the f-f transitions of R^(3+) were observed in respective CuR_xY_(1-x) O_2 and CuR_xLa_(1-x) O_2, indicating successful control of luminescence property of CuYO_2 and CuLaO_2 by doping with R. P-type conductivity of CuCa_yY_(1-y) O_2 increased with increasing Ca concentration, but those of CuCa_yLa_(1-y) O_2 and CuSr_yLa_(1-y) O_2 did not. The increase of the p-type conductivity in CuCa_yY_(1-y) O_2 is considered to be caused by substitution of Ca^(2+) … More acceptor cation for the Y^(3+) site. CuR_xCa_yY_(1-x-y) O_2 samples co-doped with R and Ca, as well as the CuR_xY_(1-x) O_2 and CuCa_yY_(1-y) O_2 samples, exhibited noticeable sharp emission lines due to the f-f transitions of R^(3+) and good p-type conductivity due to Ca^(2+) acceptor. This fact demonstrates controllability of luminescence and conductive properties of CuYO_2 by co-doping with R and Ca. Delafossite-type CuYO_2 and CuR_xY_(1-x) O_2(R: Eu, Tb)films were prepared by solution method using metal nitrates as sources. The lattice-parameter dependence on R concentration implies substitution of R^(3+) for Y^(3+) site. A green emission band due to the Cu^+ interconfiguration transition was observed in CuYO_2 films, while noticeable sharp emission lines due to the f-f transitions of Tb^(3+) and Eu^(3+) were observed in respective CuTb_xY_(1-x) O_2 and CuEu_xY_(1-x) O_2 films. These results for the films correspond well to the data for the CuR_xY_(1-x) O_2 bulk samples prepared by the conventional solid state reactions, indicating successful preparation of CuYO_2 and CuR_xY_(1-x) O_2 films via the solution method. Less