TY - JOUR
T1 - Strong enhancements of infrared-to-ultraviolet upconversion emissions in Yb 3+ and Tm 3+ Co-doped sub-micron fluoride particles prepared by using pulsed laser ablation
AU - Qin, Weiping
AU - Qin, Guanshi
AU - Chung, Yonghwa
AU - Lee, Yong Ill
AU - Kim, Changdae
AU - Jang, Kiwan
PY - 2004/4
Y1 - 2004/4
N2 - Five Tm 3+-Yb 3+ co-doped fluorides, ZnF 2, AlF 3, PbF 2, LiF, and ZAPL (30ZnF 2 - 25A1F 3 30PbF 2 - 9.8LiF - 5Yb 2O 3 - 0.2Tm 2O 3) glass, were prepared via solid state reactions. Taking them as targets, we prepared five fluoride particles by using pulsed laser ablation (PLA). Under 980 nm infrared excitation, the upconversion properties of these fluorides (targets and particles) were investigated. All of the PLA particles showed strong ultraviolet upconversion emission. Spectral analysis indicates that rare-earth ions might prefer to occupy the sites surrounded by Pb 2+ ions in the ZAPL glass. The populations of the 1I 6 and the 1G 4 levels (Tm 3+) depended on the cation radii in the particles, and the population of the 1D 2 (Tm 3+) level remained in a relative narrow range both for the targets and the PLA particles. Prolonged fluorescence lifetimes of the 1I 6, the 1D 2, and the 1G 4 levels in the PLA particles were observed, which revealed that the energy transfer process from Yb 3+ ions to Tm 3+ ions was more efficient in the PLA particles than it was in the targets. Lattice defects and structural deformation induced by PLA were found in the ZnF 2 particles by using a transmission electron microscope, and the changed fluorescence branching ratios for the transitions from the 1D 2 level was proof of a variation in the crystal structure of the PLA particles.
AB - Five Tm 3+-Yb 3+ co-doped fluorides, ZnF 2, AlF 3, PbF 2, LiF, and ZAPL (30ZnF 2 - 25A1F 3 30PbF 2 - 9.8LiF - 5Yb 2O 3 - 0.2Tm 2O 3) glass, were prepared via solid state reactions. Taking them as targets, we prepared five fluoride particles by using pulsed laser ablation (PLA). Under 980 nm infrared excitation, the upconversion properties of these fluorides (targets and particles) were investigated. All of the PLA particles showed strong ultraviolet upconversion emission. Spectral analysis indicates that rare-earth ions might prefer to occupy the sites surrounded by Pb 2+ ions in the ZAPL glass. The populations of the 1I 6 and the 1G 4 levels (Tm 3+) depended on the cation radii in the particles, and the population of the 1D 2 (Tm 3+) level remained in a relative narrow range both for the targets and the PLA particles. Prolonged fluorescence lifetimes of the 1I 6, the 1D 2, and the 1G 4 levels in the PLA particles were observed, which revealed that the energy transfer process from Yb 3+ ions to Tm 3+ ions was more efficient in the PLA particles than it was in the targets. Lattice defects and structural deformation induced by PLA were found in the ZnF 2 particles by using a transmission electron microscope, and the changed fluorescence branching ratios for the transitions from the 1D 2 level was proof of a variation in the crystal structure of the PLA particles.
KW - Pulsed laser ablation
KW - Structure transition
KW - Upconversion
UR - http://www.scopus.com/inward/record.url?scp=2442564380&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:2442564380
SN - 0374-4884
VL - 44
SP - 925
EP - 929
JO - Journal of the Korean Physical Society
JF - Journal of the Korean Physical Society
IS - 4
ER -