| 초록 |
We report a very intense near infrared to visible frequency upconversion photoluminescence in Tm3+ and Er3+ co-doped transparent α-Sialon ceramics under 980 nm laser excitation. Distinct upconversion bands at 554 nm, 668 nm, 803 nm were assigned to the transitions from 2H11/2 to 4I15/2 (Er3+), 4F9/2 to 4I15/2 (Er3+), and 3H4 to 3H6 (Tm3+) respectively. The results show that there is very efficient energy transfer between Er3+ and Tm3+ ions as a result of the coexistence of the ions into the α-Sialon lattice. The quadratic dependence of the of the emission intensity on the excitation power shows that the upconversion process is governed by two photonic process. Formation of the α-Sialon phase and existence of both Er3+ and Tm3+ ions into the lattice were confirmed by XRD, TEM, and EDS analysis. Raman spectroscopic study revealed that the α-Sialon ceramics have moderately low phonon energy (828 cm-1) as compared to some well known phosphate and oxide glasses and ceramics. The inherent outstanding thermo-mechanical properties along with the up and downconversion emission properties and moderately low phonon energy of (Tm3+, Er3+)-α-Sialon ceramics make them potential upconversion material for multifunctional applications. |
