Preparation and upconversion property of TeO sub(2:Er) super(3)+/Yb super(3+ nanoparticles)

Different crystal structure of TeO sub(2 nanoparticles were used as the host materials to prepare the Er) super(3)+/Yb super(3+ ions co-doped upconversion luminescent materials. The TeO) sub(2) nanoparticles mainly kept the original morphology and phase after having been co-doped the Er super(3+/Yb) super(3)+ ions. All the as-prepared TeO sub(2:Er) super(3)+/Yb super(3+ nanoparticles showed the green emissions (525 nm, 545 nm) and red emission (667 nm) under 980 nm excitation. The green emissions at 525 nm, 545 nm and red emission at 667 nm were attributed to the ) super(2)H sub(11/2 right arrow ) super(4)I sub(15/2, ) super(4)S sub(3/2 right arrow ) super(4)I sub(15/2 and ) super(4)F sub(9/2 right arrow ) super(4)I sub(15/2 transitions of the Er) super(3)+ ions, respectively. For the [alpha]-TeO sub(2:Er) super(3)+/Yb super(3+ (3/10 mol%) nanoparticles, three-photon process involved in the green () super(2)H sub(11/2 right arrow ) super(4)I sub(15/2) emission, while two-photon process involved in the green () super(4)S sub(3/2right arrow) super(4)I sub(15/2) and red () super(4)F sub(9/2 right arrow ) super(4)I sub(15/2) emissions. For the [beta]-TeO) sub(2):Er super(3+/Yb) super(3)+ (3/10 mol%) nanoparticles, two-photon process involved in the green ( super(2H) sub(1)1/2 right arrow super(4I) sub(1)5/2), green ( super(4S) sub(3)/2 right arrow super(4I) sub(1)5/2) and red ( super(4F) sub(9)/2 right arrow super(4I) sub(1)5/2) emissions. It suggested that the crystal structure of TeO sub(2 nanoparticles had an effect on transition processes of the Er) super(3)+/Yb super(3+ ions. The emission intensities of the [alpha]-TeO) sub(2):Er super(3+/Yb) super(3)+ (3/10 mol%) nanoparticles and [beta]-TeO sub(2:Er) super(3)+/Yb super(3+ (3/10 mol%) nanoparticles were much stronger than those of the ([alpha] + [beta])-TeO) sub(2):Er super(3+/Yb) super(3)+ (3/10 mol%) nanoparticles.