Photoluminescence properties and energy transfer of Ce3+–Tb3+ co-doped SrAlF5 nanorods by a hydrothermal method

Abstract

Ce³⁺ and Tb³⁺ co-doped SrAlF₅ nanorods were synthesized via a mild hydrothermal method. The XRD results show that the prepared samples are single-phase. FE-SEM reveals the high uniformity of the as-synthesized nanorods (∼1 μm in length and ∼50 nm in diameter). The effect of reaction conditions on the morphology of SrAlF₅ was studied. When excited at 254 nm, contrasting weak emission signals of SrAlF₅:Tb³⁺ were observed, while SrAlF₅:Ce³⁺,Tb³⁺ nanorods exhibited the strong green emission of Tb³⁺ ions. The energy transfer between Ce³⁺ and Tb³⁺ was observed and studied. The mechanism of energy transfer was deduced to be the electric dipole–dipole interaction in the SrAlF₅ host. The optimum doping concentration of Ce³⁺ ions is 7 mol% in SrAlF₅:0.01Tb³⁺. The fluorescence decay curves for Ce³⁺ and Tb³⁺ of SrAlF₅:Ce³⁺,Tb³⁺ nanorods were measured at room temperature. The lifetime of Ce³⁺ is in the range from 78.6 to 1.2 ns and the lifetime of Tb³⁺ varies from 4.39 to 7.39 ms. The energy transfer efficiency from Ce³⁺ to Tb³⁺ was calculated using lifetime and emission spectra. The chromaticity coordinates of all the samples were calculated and the chromaticity coordinates of SrAlF₅:0.06Ce³⁺,0.01Tb³⁺ are very near those of the European broadcasting union (EBU) primary green color (0.29, 0.60).