Wydział Chemii

Georges Boulon

Yannick Guyot

Małgorzata Guzik

Thierry Epicier

Paweł Głuchowski

Dariusz Hreniak

Wiesław Stręk

2014

Journal of Physical Chemistry C

118

15474-15486

10.1021/jp502882j

Naukowa

Angielski

Artykuł

We show the approach in the structural and spectroscopic analysis of Yb³⁺-doped YAG nanoceramics prepared using the low temperature-high pressure sintering technique (LTHP) by conjugation of both TEM-EDX and optical techniques. Pressure sintering dependences of absorption, emission, and decays are analyzed and interpreted. The sample pressurized at 8 GPa for sintering is characterized by the highest transparency and confirms the Y₃Al₅O₁₂ garnet structure of the grains of ∼21 nm average size. Yb³⁺ ion distribution has been analyzed by both TEM-EDX evaluation in grains and grain boundaries and spectroscopy of Yb³⁺ pairs of small population from the co-operative luminescence phenomenon. EDX analysis at the TEM scale provides unambiguous results on a clear tendency of almost uniform Yb³⁺ distribution. An important new observation has been made at 4 K and room temperature with the ²F_7/2 → ²F_5/2 0-phonon absorption line located at 975.7 nm, in addition of the 0-phonon line of the YAG structure of grains at 968 nm similar to that of bulky YAG single crystals. We have discussed the origin of this new 0-phonon line relaxing only by nonradiative transitions and conclude that this line might be assigned to Yb³⁺ distorted sites on the grain surfaces.

http://dx.doi.org/10.1021/jp502882j

https://www.acs.org/content/acs/en.html