Phonon-assisted energy back transfer-induced multicolor upconversion emission of Gd2O3:Yb(3+)/Er(3+) nanoparticles under near-infrared excitation.

Phonon-assisted energy back transfer-induced multicolor upconversion emission of Gd2O3:Yb(3+)/Er(3+) nanoparticles under near-infrared excitation.