Local Environments Around Eu³⁺ and Eu²⁺ Ions in Dual Light‐Emitting BaSnO₃:Eu Nanomaterials

Abstract The change in the environment around Eu 3+ and Eu 2+ species as a function of their concentration in BaSnO 3 :Eu nanomaterials has been investigated by low‐temperature (77 K) luminescence and electron paramagnetic resonance (EPR) spectroscopy. These materials show dual emission from the europium ions upon single‐wavelength excitation. Europium ions (Eu 3+ and Eu 2+ ) occupy the centrosymmetric Ba 2+ sites up to 4 atom‐% in BaSnO 3 , beyond which it forms a separate europium oxide phase with both Eu 2+ and Eu 3+ ions. There is energy transfer from the BaSnO 3 host to the Eu 2+ ions in the samples. Upon single‐wavelength UV excitation (280 nm) of the BaSnO 3 :Eu nanomaterials, strong emissions at 430, 480, 590 and 612 nm, characteristic of exciton recombination in the host BaSnO 3 (430 nm), the 4f 6 5d 1 (T 2g )→4f 7 ( 8 S 7/2 ) transition of Eu 2+ (480 nm) and intra‐4f transitions of Eu 3+ (590 and 612 nm) have been observed. For samples that contain more than 4 atom‐% europium ions based on steady‐state luminescence measurements and lifetime values that correspond to the 5 D 0 level of Eu 3+ ions, it is inferred that there are mainly three types of Eu 3+ ions: the first at Ba 2+ sites with perfect dodecahedral geometry in the bulk of the nanomaterials, the second at Ba 2+ sites at the surface of the nanomaterials and the third type as a separate europium oxide phase. Similarly, EPR specroscopy confirms the presence of three types of environments for the Eu 2+ species.

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