Infrared to Visible Upconversion Luminescence in Yb3+, Ho3+: Y2O3 Nanocrystalline Powders
Yb3+, Ho3+ co-doped Y2O3 nanocrystalline powders were synthesized via a reverse-strike co-precipitation method using nitrates and ammonia as raw materials. The as-prepared powders are cubic Y2O3 after fired at 7000C for 2 h. Field emission scanning electronic microscopy revealed that most of the particles are nearly spherical and the average diameter of the particles is in the range of 60-80 nm. Under the excitation with a 980 nm continuous wave diode laser, two main emission bands, i.e., green emission centered at 549 nm and red emission centered at 666 nm is observed, respectively. The green emission is attributed to the transition of (5S2, 5F4-5I8) levels of Ho3+; while for the red emission, the transition of 5F5-5I8 levels is suggested. In addition, near infrared emission centered at 755 nm is also detected, corresponding to the transition of (5S2, 5F4-5I7) levels. The dependence of the intensity of upconversion emissions upon the pump power of the diode laser suggests that two-photon absorption mechanism be involved in these processes.
Omer Van der Biest, Michael Gasik, Jozef Vleugels
J. Zhang et al., "Infrared to Visible Upconversion Luminescence in Yb3+, Ho3+: Y2O3 Nanocrystalline Powders ", Materials Science Forum, Vols. 492-493, pp. 95-100, 2005