Photoluminescence of Doped YAG Transparent Ceramics Fabricated by Spark Plasma Sintering

Abstract

Doped transparent ceramics have potential for a wide range of optical applications derived from their easily controllable fluorescence properties. The aim of this contribution is to present and discuss an effective fabrication method for doped transparent yttrium aluminum garnet ceramics. The powder synthesis route was adapted from common co‐precipitation methods and the powder densification was performed by spark plasma sintering. Parameters of the fabrication process were optimized for different lanthanide dopants in order to obtain highly transparent single‐ and multi‐doped ceramics. The photoluminescence properties of the samples were measured and discussed. The use of lithium fluoride as a sintering additive was confirmed to be favorable and post‐sintering heat treatments were shown to be necessary for certain dopants. Finally, the photoluminescence lifetime of dopants in a multi‐doped sample were measured and the energy transfer efficiency between dopants was determined.

Pressure-assisted sintering and characterization of Nd:YAG ceramic lasers

“…The simplest measure of scattering losses in a sample is transmittance measurements. We have shown here and previously 36 , 54 that the in-line transmittance spectra (detecting light scattered at angles smaller than ~ 1°) of SPS samples are higher compared to HPSPS. It was established that Mie scattering (forward directional) dominates in SPS-processed samples and Rayleigh scattering (random direction) dominates in HPSPS-processed samples.…”

“…Since, Nd substitutes for Y in the YAG lattice, the precise YAG stoichiometry was maintained by adding the correct molar ratio of Al nitrate nonahydrate (Al(NO 3 ) 3 ·9H 2 O, 99%; Alfa Aesar). This process is described in detail in our previous contributions 36 , 54 and included lyophilization and subsequent calcination treatments. The powders were consolidated to fabricate single-phase highly transparent ceramics by means of an SPS apparatus (HP-D10 FCT Systeme, Rauenstein, Germany) under conventional (60 MPa) and high-pressure conditions (300 MPa), namely SPS and HPSPS, respectively.…”

Simplified Single‐Step Fabrication of Composite Transparent Ceramics

“…The 9 at% Yb:YAG exhibits an aquamarine color (Figure 4a) because of Yb 2+ state of part of the dopant ions following the reducing atmosphere during SPS. [ 39 ] The border area was examined by a high‐resolution scanning electron microscope (HRSEM) and energy‐dispersive X‐ray spectroscopy (EDS) line analysis was performed across the border (Figure 4b). There is no apparent difference in the microstructure between the doped and undoped areas but the gradual change in the ratio between Y and Yb is evident and reflects a diffusion region of about 20 μm.…”

“…In addition, in‐house doping of YAG powders with 5 at% Nd and 0.5 at% Ce (with some having 0.2–1 at% Cr) was performed via a coprecipitation approach followed by freeze drying and subsequent calcination, as described in detail elsewhere. [ 39 ] Prior to sintering, 0.3 wt% LiF powder (99.99%, Alfa Aesar, Haverhill, MA) was added as a sintering aid to all the YAG powders. Additionally, commercial magnesium aluminate spinel (MgAl 2 O 4 ) nanopowder (S30CR, ≥99%, Baikowski, France) was used for a couple of experiments as either undoped or doped with 0.08 at% Co 2+ [ 54 ] by the same coprecipitation method.…”