Two kinds of trivalent lanthanide ions (Ln3+) were substitutionally doped in the cubic perovskite-type BaSnO3 and their effects on optical and electrical properties were investigated. La3+ was fixed as the first dopant because of its electron-donor nature, while the second dopant was selected from luminescent Ln3+ ions, namely, Pr3+, Sm3+, Eu3+, or Tb3+. In preliminary screening, Sm3+ was found to exhibit strong photoluminescence (PL) through an efficient O2––Sm3+ charge transfer excitation. Then, powders and sintered pellets of Ba1–x–yLaxSmySnO3 compositions (x = 0–0.04 and y = 0.001–0.06) were prepared through a polymerized complex method and their PL intensity and electrical resistivity were measured and compared among the samples. The PL intensity of the powder samples increased with the increasing Sm3+ content y at any La3+ content x. However, at the fixed Sm3+ content y, the PL intensity decreased with the increasing La3+ content x. The electrical resistivity of the pellet samples decreased with the increasing La3+ content x, while it increased considerably with the increasing Sm3+ content y. The dependence of the above physical properties on the La3+ and Sm3+ contents was discussed in association with the formal valence change of Sn4+ after the dual La3+/Sm3+ doping in BaSnO3.
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