Preparation and Luminescent Properties of Delafossite-Type CuLaO₂ Doped with II-Group Elements

Abstract

Single-phase delafossite-type CuM_xLa_1-xO₂ (M=Mg, Ba, Ca, Sr, Mg, Zn, Cd) was synthesized by means of the solid-state reaction of a stoichiometrically mixed powder of binary oxides at 1273 K, for 10 h in an argon flow, and their luminescent properties were investigated. Undoped CuLaO₂ exhibited a weak yellow-green photoluminescence-emission band due to the Cu⁺ interconfiguration transition at room temperature. The effect of II-group element doping on the photoluminescent properties was classified into two types. CuSr_xLa_1-xO₂, CuBa_xLa_1-xO₂ and CuZn_xLa_1-xO₂ (x≤0.01) exhibited the emission slightly shifted to the shorter-wavelength side than that of undoped CuLaO₂ and a strong emission intensity, with increasing doping concentration. These emission behaviors in CuSr_xLa_1-xO₂, CuBa_xLa_1-xO₂ and CuCa_xLa_1-xO₂ was considered to be due to the formation of new emission centers upon doping Sr, Ba and Ca, respectively. CuZn_xLa_1-xO₂, CuCd_xLa_1-xO₂ and CuMg_xLa_1-xO₂ (x≤0.01) exhibited the emission similar to one due to the Cu⁺ interconfiguration transition in undoped CuLaO₂ and a weaker emission intensity, with increasing doping.