Broadened band C-telecom and intense upconversion emission of Er3+/Yb3+ co-doped CaYAlO4 luminescent material obtained by an easy route

Abstract

This work reports on photoluminescence properties of Er 3 þ /Yb 3 þ co-doped CaYAlO 4 in powder form, synthesized by an easy route using citric acid as ligand to form complex precursor. The 1.2 mol% of Yb 3 þ was fixed, while the amount of Er 3 þ changed in 0.5, 1.5 and 3 mol% in order to evaluate the photoluminescence properties as a function of the Er 3 þ concentration. The structural and thermal properties of the viscous solutions and powder materials obtained after the heat-treatment at 1000, 1100 and 1200°C for 4 h were evaluated by XRD, FTIR and TG/DTA analysis. The results showed the formation of pure CaYAlO 4 tetragonal crystalline phase after heat-treatment at 1100°C and 1200°C. Intense emission in the visible region under excitation at 980 nm was attributed to upconversion process, from Er 3 þ intraconfigurational f-f transitions. The emissions were assigned to the transitions 2 H 11/2-4 I 15/2 and 4 S 3/ 2-4 I 15/2 (green region), and 4 F 9/2-4 I 15/2 (red region) energy levels. The ratio between emission band integrated areas assigned to the red and green emissions increased as a function of Er 3 þ concentration. Under excitation at 980 nm with 100 mW of power pump, the materials also showed intense and broadening emission with maximum at 1520 nm with FWHM of 84.74 nm for the sample CaYAlO 4 :1.5% Er 3 þ /1.2% Yb 3 þ heat-treated at 1000°C for 4 h. The photoluminescence properties showed that these materials are promising for use in C-telecom band as optical amplifier biological marker or/and solidstate laser devices under excitation at 980 nm.

Up- and Down-Convertible LaF3:Yb,Er Nanocrystals with a Broad Emission Window from 350 nm to 2.8 μm: Implications for Lighting Applications

“…High-energy excitation states undergo nonradiative relaxation to the 4 I 13/2 level of Er 3+ , followed by emission at ∼1550 nm owing to an 4 I 13/2 → 4 I 15/2 electronic transition (Figure 5d). 42 Moreover, the DC emission intensity increased monotonically with increasing Yb 3+ concentration (Figure 5b), analogous to the red band in the case of the UC process. Additionally, MIR emission was observed around 2.8 μm (Figure 5d) from the LFYE NCs as a result of the 4 I 11/2 → 4 I 13/2 electronic transition of Er 3+ , as proposed in the energy level diagram shown in Figure 5e.…”

“…The mechanism of the NIR emission at 1550 nm involves 980 nm excitation of Yb 3+ from 2 F 7/2 to 2 F 5/2 states, followed by relaxation to the 4 I 11/2 level of Er 3+ via ET (Figure d). High-energy excitation states undergo nonradiative relaxation to the 4 I 13/2 level of Er 3+ , followed by emission at ∼1550 nm owing to an 4 I 13/2 → 4 I 15/2 electronic transition (Figure d) . Moreover, the DC emission intensity increased monotonically with increasing Yb 3+ concentration (Figure b), analogous to the red band in the case of the UC process.…”

Luminescent Materials Based on Aluminates: A Review

“…[ 399 ] Tetragonal CaYAlO 4 has a low phonon energy of around 322 cm −1 , making it a suitable host for UC based on the Yb–Er pair. [ 400 ] Oliva et al [ 401 ] obtained luminance values of the yellow and green emissions 1365 and 1813 cd m −2 , respectively, in an orthorhombic BaLaAlO 4 host.…”