Synthesis and luminescence properties of Tb3+/Eu3+ co-doped GdAlO3 phosphors with enhanced red emission

Abstract

The (Gd0.97–xEuxTb0.03)AlO3 (x = 0.005–0.07) phosphors were synthesized by the co-precipitation method, using ammonium bicarbonate as a precipitant. The combined technologies of FT-IR, XRD, FE-SEM, PLE/PL and photoluminescence decay analysis were used to study the phase evolution, morphologies and luminescent properties. The phosphors with good dispersion exhibit strong vivid red emission located at 617 nm (5D0-7F2 transition of Eu3+) under the optimal excitation wavelength of 275 nm (4f8-4f75d1 transition of Tb3+, 8S7/2 → 6IJ transition of Gd3+). The presence of Gd3+ and Tb3+ excitation bands on the PLE spectra monitoring the Eu3+ emission directly gives an evidence of Tb3+ → Eu3+ and Gd3+ → Eu3+energy transfer. The emission intensity varies with the Eu3+ amount, and the quenching concentration is ∼5 at% which is close to the calculated value. The quenching mechanism is determined to be the exchange reaction between Eu3+. The temperature-dependent PL analysis indicates that the best (Gd0.92Eu0.05Tb0.03)AlO3 sample possesses good thermally stable properties. All the (Gd0.97–xEuxTb0.03)AlO3 phosphors in this work have similar CIE chromaticity coordinates and color temperatures, which are (0.65 ± 0.02, 0.35 ± 0.02) and ∼2558 K, respectively. Fluorescence decay analysis shows that the lifetime for ∼617 nm emission decreases with the content of Eu3+ and temperature increasing. Owing to the Tb3+ → Eu3+ energy transfer, the luminescent properties of the (Gd0.92Eu0.05Tb0.03)AlO3 phosphors are superior to the single Eu3+ doped sample (Gd0.95Eu0.05)AlO3. As a result, the prepared phosphors may be widely used in solid-state display and light emitting devices.