Daisuke Matsuura

Red, green, and blue upconversion luminescence of trivalent-rare-earth ion-doped Y2O3 nanocrystals

Trivalent-rare-earth ion-doped Y2O3 nanocrystals have been synthesized, and their photoluminescence properties have been studied under 980 nm laser diode excitation. The crystallite size estimated by x-ray diffractometry and scanning electron microscopy was about 30–40 nm. In Yb3+ and Tm3+ codoped Y2O3 nanocrystals, the bright blue emissions near 450 and 480 nm have been noticeable due to the 1D2–3F4 and 1G4–3H6 transitions of Tm3+, respectively. The bright green emissions of Er3+ doped Y2O3 nanocrystals appeared near 530 and 550 nm were assigned to the 2H11/2–4I15/2 and 4S3/2–4I15/2 transitions of Er3+, respectively. The ratio of the intensity of green luminescence to that of red luminescence has decreased with an increase of concentration of Yb3+ in Er3+ doped Y2O3 nanocrystals. In sufficient quantities of Yb3+ to Er3+, the bright red emission near 660 nm has been predominant due to the 4F9/2–4I15/2 transition of Er3+. The primary color components are in these red, green, and blue emissions, from which ...

Upconversion Luminescence Properties of Y 2 O 3 Nanocrystals Doped with Trivalent Rare-Earth Ions

Upconversion luminescence properties of Y 2 O 3 nanocrystals doped with Er 3 + and codoped with Er 3 + and Yb 3 + under excitation with a 980 nm laser diode have been studied. The green and red luminescence, which are attributed to the 2 H 1 1 / 2 to 4 I 1 5 / 2 , 4 S 3 / 2 to 4 I 1 5 / 2 , and 4 F 9 / 2 to 4 I 1 5 / 2 transitions of Er 3 + , have been observed from Y 2 O 3 nanocrystals doped with Er 3 + as well as those codoped with Er 3 + and Yb 3 + . Photoluminescence properties of three transitions of Er 3 + , related to the Er 3 + concentration in Y 2 O 3 nanocrystals and Yb 3 + concentration in Y 2 O 3 nanocrystals doped with 1 mol % Er 3 + , have been investigated in detail. For Y 2 O 3 nanocrystals doped with 1 mol % Er 3 + , the slope values of the line corresponding to the photoluminescence intensities of the three transitions as a function of pump power are approximately 2 due to two-photon absorption by Er 3 + only. Otherwise, for Y 2 O 3 nanocrystals doped with 10 mol % Er 3 + and codoped with 1 mol % Er 3 + and 5 mol % Yb 3 + , both the slope values are less than 2. These results are related to the energy-transfer process of trivalent rare-earth ions.