Journal of the American Ceramic Society , 2006, 89 (6), 2027-2033.

Structural and optical properties of highly Nd-doped yttrium aluminum garnet ceramics from alkoxide and glycolate precursors

Mathur, Sanjay | Shen, Hao | Veith, Michael | Rapalaviciute, Rasa | Agne, Thomas

Yttrium aluminum garnet (YAG) nanopowders doped with high neodymium (Nd) content (3 at.%) were synthesized by the sol-gel processing of (I) alkoxide precursors and (II) metal chelates formed by complexing the cations with polyethylene glycol. A stoichiometric YAG composition was obtained following both procedures; however, the agglomeration of particles was significantly higher in glycolate synthesis, which shielded residual organics from oxidation (elemental analyses). Distribution of Nd

3+

ions in the YAG matrix, as shown by the absorption of pump energy and photoluminescence spectra of Nd:YAG ceramics, was more homogeneous in alkoxide-derived powders. The segregation of Nd centers in the glycolate-derived sample was supported by the precipitation of a crystalline Nd

2

O

3

phase (X-ray diffraction) during sintering. High-resolution absorption spectra (

4

I

9/2

(1)-

4

F

9/2

(1)) of the powders showed that a higher absorption cross-section of glycolate-derived powders is due to Nd

3+

-Nd

3+

ion pairing, which leads to the quenching of photoluminescence. Owing to the better dispersion of optically active centers, the photoluminescence signal was found to be substantially enhanced in alkoxide-derived Nd:YAG ceramics.