Hydrothermal Tm3+−Lu2O3 Nanorods with Highly Efficient 2 μm Emission
journal contributionposted on 04.04.2011, 00:00 by Fátima Esteban-Betegón, Carlos Zaldo, Concepción Cascales
Cubic Ia3̅ Tm−Lu2O3 porous nanorods of ∼45 μm length and 90 nm diameter have been prepared with precise compositions through a soft hydrothermal route (i.e., autogenic pressure, neutral pH, and 185 °C for 24 h) by using chloride reagents. For these nanorods, room temperature excitation and photoluminescence spectra of Tm3+ multiplets related to the eye-safe 3F4→3H6 laser transition at ∼1.85−2.05 μm are similar to those of bulk crystals. Room-temperature luminescence decays of 3H4 and 3F4 exhibit nonexponential dynamics analytically reproduced by the sum of two exponential regimes, which are ascribed to the different rates of nonradiative relaxations in defects at the surface and in the body of the nanocrystals, respectively. Measured fluorescence lifetimes τ ∼ 200−260 μs and τ ∼ 2.3−2.9 ms for 3H4 and 3F4, respectively, in 0.2% mol Tm−Lu2O3 nanorods, are considerably larger than in previous nanocrystalline Tm-doped sesquioxides, and they are close to values of bulk sesquioxide crystals with equivalent Tm3+ content.