Influence of Li+ codoping on visible emission of Y2O3:Tb3+, Yb3+ phosphor.

Upon 980 nm diode laser excitation visible upconversion emission from the Tb(3+) ions has been observed in combustion synthesized Tb(3+)-Yb(3+) codoped Y2O3 phosphor. The intensity of upconversion as well as downconversion emission bands has been increased by codoping of Li(+) ions into Tb(3+)-Yb(3+):Y2O3 phosphor and the reason behind this increment is discussed. The pump power dependence of upconversion emission bands has shown two-photon absorption process. The cooperative energy transfer from Yb(3+) to Tb(3+) ions is supposed to be responsible for the upconversion emission from the Tb(3+) ions on near infrared excitation. The calculated colour coordinates indicate the purity of intense green emission from present phosphor which is suitable for various photonic applications.