Na 0.90- y AlSiO 4 :0.1Er 3+ , y Yb 3+ (0 ≤ y ≤ 0.007) phosphors were prepared by the solid state reaction method and their dual mode multicolor luminescence properties were systematically investigated. The phosphors were crystallized into the carnegieite polymorph of NaAlSiO 4 at 1300 °C. The synthesized phosphors were characterized by using powder XRD technique, FT-IR and UV-VIS-NIR diffuse reflectance spectra. Upon 380 nm excitation, the phosphors emitted visible and NIR downconversion emission, which follows the quantum cutting process. The upconversion emission spectra , irrespective of the laser excitation wavelength (980 nm, 808 nm, or 1550 nm), show characteristics sharp green, and red emissions, from 2 H 11/2 → 4 I 15/2 , 4 S 3/2 → 4 I 15/2 , and 4 F 9/2 → 4 I 15/2 transitions of Er 3+ , respectively. Intense green (552 nm), red (664 nm) and NIR (809 nm) emissions were observed at 980, 808 and 1550 nm laser excitation, respectively. The dual mode emission of the Na 0.90- y AlSiO 4 :0.1Er 3+ , y Yb 3+ (0 ≤ y ≤ 0.007) phosphors is enhanced upon Yb 3+ co-doping. By analyzing the dependence of upconversion emission intensities on the laser excitation power, a possible upconversion emission mechanism is proposed.
Zhurong Mo,Yanping Huo,Haoyi Wu,Brij Mohan,Hongli Wen,Li Luo,Deshmukh Abdul Hakeem
We report the synthesis and the effect of synthesis temperature on the crystal structure and dual mode (DC/UC) luminescence properties of the NASE-1000–1300. Two different polymorphs, i.e., nepheline and carnegieite of the NASE have been prepared just by changing the annealing temperature. Multi wavelength excitation can be used to obtain different emissions in visible and NIR regions. Under 380 and 980 nm excitation, the NASE-1000–1300 produces 1535 nm NIR emission, whereas green and red visible emissions are observed with 980 and 808 nm laser excitations. Under 980 nm laser excitation, the synthesis temperature dependent nepheline and carnegieite polymorphs emit intense red and green emission, respectively. Two-photon process is responsible for the green and red UC emissions of the NASE-1300. The NASE-1000-1300 produces intense red emission under 808 nm laser excitation. We believe that the NASE-1000–1300 could be a promising candidate for the photonic as well as biological applications.
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