Luminescence Properties of Delafossite-Type CuYO₂ Doped with Calcium, Oxygen or Rare Earth Tb

Abstract

Delafossite-type CuYO2 and CuY1-x Ca x O2 (x≤0.05) samples exhibited a green-PL-emission band due to the Cu+ interconfiguration transition from 3d94s1 to 3d10 at room temperature. With increasing Ca concentration, the Cu+ emission shifted slightly to the shorter-wavelength side with a slightly weaker emission intensity. This slight change in Cu+ emission property is considered to be caused by the increase in hole concentration within the Cu+ layer arising from the increase in Ca concentration. On the other hand, oxygen-annealed CuYO2 samples exhibited no emissions. The increase in nonradiative relaxation processes in the oxygen-annealed CuYO2 samples is possibly related to structural changes such as orthorhombic distortion during the oxygen annealing. In the photoluminescence of delafossite-type CuY1-y Tb y O2 (y=0.05) at room temperature, no Cu+ emission band was observed, but sharp emission lines were observed. All the emission lines were assigned to the f-f transitions of Tb3+ (5D4→7F J , J=3–6).

P‐type conductive CuYO2 phosphor Co‐doped with Eu, Tb or Tm rare‐earth cation and Ca acceptor cation

“…1, the concentration quenching at the lower Tm concentration is also assumed to be related to the smaller distance between the Y 3+ sites in Table 1. Increase of p-type conductivity with increasing Ca concentration indicates doping with Ca 2+ acceptor cation on the Y 3+ site, causing hole concentration increases in co-doped CuR x Ca y Y 1-x-y O 2 samples, as reported previously in CuCa x Y 1-x O 2 samples [3,4,8,9]. The cause of the differences in the conductivity of CuR x Ca y Y 1-x-y O 2 samples with the same Ca concentration y is not yet clear.…”

“….08, y = 0.02~0.05), and that electrical conductivity of CuTb x Ca y Y 1-x-y O 2 were larger than that of CuTb x Y 1-x O 2 [9,10]. In addition, CuEu x Y 1-x O 2 (x ≤ 0.08) and CuEu x Ca y Y 1-x-y O 2 (x = 0.08, y = 0.02) have been tentatively prepared and characterized [10].…”

Effect of Ca-doping on the structural and electrical properties of CuY1−xCaxO2 (0≤x≤0.10) ceramics

“…Electrical conductivities increase with the increase of temperature over the measured temperature range, indicating semiconducting behavior. It is reported that Ca-doping could enhance the electrical conductivity of CuYO 2 by introducing positive holes [19,21,[23][24][25]28]. In our experiment, the conductivities increase with the dopant concentration x when 0 ≤ x ≤ 0.06 and then decrease with x when 0.06 ≤ x ≤ 0.10, which may be ascribed to second phase formation.…”

“…Delafossites ABO 2 can form either rhombohedral 3R (R3m) or hexagonal 2H (P6 3 /mmc) structures, depending on the stacking of the layers [18]. In the previous studies, the crystal structure, luminescence property and thermoelectric power of CuYO 2 were studied; its application to p-TCOs and hydrogen photocathode was explored [19][20][21][22]. Ca 2+ doped CuYO 2 has also been reported in the previous studies [23][24][25].…”

Preparation of delafossite-type CuCrO2 films by sol–gel method

“…The first report on p-type TCO films of NiO was published in 1993 [5]. Delafossites such as CuScO 2 [6], CuFeO 2 [7], CuInO 2 [8], CuYO 2 [9], CuCoO 2 [10] have been widely studied since the discovery of p-type conductivity in transparent CuAlO 2 thin films in 1997 [11], which initiated extensive interest in this type of materials. Even though the electrical performance of these materials will never be able to compete with the well-established n-type TCOs such as Al-doped zinc oxide (AZO) or indium-tin oxide (ITO) due to their intrinsic low carrier mobility.…”