Published in:Journal of the American Ceramic Society
Language:
English
DOI:
10.1111/jace.12898
ISSN:
0002-7820;
1551-2916
Origination:
Footnote:
Description:
<jats:p>Results of the spectroscopic characteristics and upconversion luminescence in <jats:styled-content style="fixed-case"><jats:roman>Er</jats:roman></jats:styled-content><jats:sup>3+</jats:sup> doped yttria (<jats:styled-content style="fixed-case"><jats:roman>Y</jats:roman></jats:styled-content><jats:sub>2</jats:sub><jats:styled-content style="fixed-case"><jats:roman>O</jats:roman></jats:styled-content><jats:sub>3</jats:sub>) transparent ceramics prepared by a modified two‐step sintering method are presented. The near‐infrared (1.5 μm) luminescence properties were evaluated as a function of <jats:styled-content style="fixed-case"><jats:roman>Er</jats:roman></jats:styled-content><jats:sup>3+</jats:sup> concentration. Judd–Ofelt intensity parameters, radiative rates, branching ratios, and emission lifetimes were determined and compared with results reported for <jats:styled-content style="fixed-case"><jats:roman>Er</jats:roman></jats:styled-content><jats:sup>3+</jats:sup>‐doped <jats:styled-content style="fixed-case"><jats:roman>Y</jats:roman></jats:styled-content><jats:sub>2</jats:sub><jats:styled-content style="fixed-case"><jats:roman>O</jats:roman></jats:styled-content><jats:sub>3</jats:sub> single crystal and nanocrystals. Following pumping at 1.532 μm, weak blue (~0.41 μm, <jats:sup>2</jats:sup><jats:styled-content style="fixed-case"><jats:roman>H</jats:roman></jats:styled-content><jats:sub>9/2</jats:sub> → <jats:sup>4</jats:sup><jats:styled-content style="fixed-case"><jats:roman>I</jats:roman></jats:styled-content><jats:sub>15/2</jats:sub>), strong green (~0.56 μm, <jats:sup>2</jats:sup>H<jats:sub>11/2</jats:sub>, <jats:sup>4</jats:sup>S<jats:sub>3/2</jats:sub> → <jats:sup>4</jats:sup>I<jats:sub>15/2</jats:sub>), and red (~0.67 μm, <jats:sup>4</jats:sup>F<jats:sub>9/2</jats:sub> → <jats:sup>4</jats:sup>I<jats:sub>15/2</jats:sub>) emission bands were observed as well as weak near‐infrared emissions at 0.8 μm (<jats:sup>4</jats:sup>I<jats:sub>9/2</jats:sub> → <jats:sup>4</jats:sup>I<jats:sub>15/2</jats:sub>) and 0.85 μm (<jats:sup>4</jats:sup>S<jats:sub>3/2</jats:sub> → <jats:sup>4</jats:sup>I<jats:sub>13/2</jats:sub>) at room temperature. The upconversion luminescence properties under ~1.5 μm pumping were further investigated through pump power dependence and decay time studies. Sequential two‐photon absorption leads to the <jats:sup>4</jats:sup>I<jats:sub>9/2</jats:sub> upconversion emission, whereas energy‐transfer upconversion is responsible for the emission from the higher excited states <jats:sup>2</jats:sup>H<jats:sub>9/2</jats:sub>, <jats:sup>2</jats:sup>H<jats:sub>11/2</jats:sub>, <jats:sup>4</jats:sup>S<jats:sub>3/2</jats:sub>, and <jats:sup>4</jats:sup>F<jats:sub>9/2</jats:sub>. The enhanced red emission with increasing Er<jats:sup>3+</jats:sup> concentration most likely occurred via the cross‐relaxation process between (<jats:sup>4</jats:sup>F<jats:sub>7/2</jats:sub> → <jats:sup>4</jats:sup>F<jats:sub>9/2</jats:sub>) and (<jats:sup>4</jats:sup>I<jats:sub>11/2</jats:sub> → <jats:sup>4</jats:sup>F<jats:sub>9/2</jats:sub>) transitions, which increased the population of the <jats:sup>4</jats:sup>F<jats:sub>9/2</jats:sub> level.</jats:p>