Enhancement of up-conversion luminescence of Y₂Ti₂O₇:Yb³⁺/Ho³⁺ nanocrystals by incorporating Li⁺ ions

Abstract

Tri-doped (Y 0.915 Ho 0.01 Yb 0.075 Li x ) 2 Ti 2 O 7 (x = 015.0 mol %) nanocrystals were fabricated via a facile glycine combustion approach. The crystal structure, morphology and up-conversion spectra of the as-obtained products were investigated using X-ray powder diffractometer (XRD), transmission electron microscope (TEM), spectrophotometer pumped by 980 nm diode laser, and Fourier transform infrared spectrometer. XRD results demonstrated that, owing to the flux effect of /Ho3+ samples, the green and red emission intensity of nanocrystals tri-doped with 12.5 mol % Li + was enhanced by 10.2 and 4.8 times, respectively. The emission increase should be mainly ascribed to the distortion of local symmetry around Ho 3+ ions by Li + -doping. In addition, the pump power dependence of integrated intensity suggested that both green and red emission was two-photon population process.