Enhancement of upconversion luminescence due to the formation of nanocrystals in Er~(3+)-doped tellurite glasses

摘要

Optically transparent Er~(3+)-doped tellurite-based nanocrystallized glasses with the composition of 70TeO_2·15Li_2O·15Nb_2O_5·0.5Er_2O_3 (mol) have been prepared by a conventional melting quenching and the subsequent heat treatment processes. The sizes of grown nanocrystals in glass matrix appear to be 35 — 50 nm from the X-ray diffraction (XRD) measurement. The microhardness measurement shows that the Vickers hardness values of the nanocrystallized tellurite glasses are larger (33% — 62%) than those in the base glass. The Raman spectra imply that the maximum phonon energy of the based glass decreases and shifts from 668 to 638 cm~(-1) after heat-treatment. Visible upconversion luminescence and infrared luminescence of the base glass and heat-treated glasses under 980-nm laser diode (LD) excitation are investigated. The 524-, 546- and 656-nm upconversion intensities by 980-nm pumping increase significantly.