Microstructuration induced differences in the thermo-optical and luminescence properties of Nd:YAG fine grain ceramics and crystals

Abstract

Third-order nonlinear optical response and photoluminescence characterization of tellurite glasses with different alkali metal oxides as network modifiers J. Appl. Phys. 110, 083110 (2011) In-plane thermal conductivity determination through thermoreflectance analysis and measurements J. Appl. Phys. 110, 084313 (2011) Tuning of a cavity in a silicon photonic crystal by thermal expansion of an elastomeric infill Appl. Phys. Lett. 99, 111113 (2011) Assessing the thermal conductivity of non-uniform thin-films: Nanocrystalline Cu composites incorporating carbon nanotubes J. Appl. Phys. 110, 023506 (2011) Strong absorption and selective thermal emission from a midinfrared metamaterial Appl. Phys. Lett. 98, 241105 (2011) Additional information on J. Chem. Phys. The temperature and compositional dependences of thermo-optical properties of neodymium doped yttrium aluminum garnet ͑YAG͒ crystals and fine grain ceramics have been systematically investigated by means of time-resolved thermal lens spectrometry. We have found that Nd:YAG ceramics show a reduced thermal diffusivity compared to Nd:YAG single crystals in the complete temperature range investigated ͑80-300 K͒. The analysis of the time-resolved luminescent properties of Nd 3+ has revealed that the reduction in the phonon mean free path taking place in Nd:YAG ceramics cannot be associated with an increment in the density of lattice defects, indicating that phonon scattering at grain boundaries is the origin of the observed reduction in the thermal diffusivity of Nd:YAG ceramics. Finally, our results showed the ability of the time-resolved thermal lens to determine and optimize the thermo-optical properties of Nd:YAG ceramic based lasers.

Elastic and thermodynamic properties of cerium‐doped yttrium aluminum garnets

“…Second, other studies suggest that impurity/grain boundary phonon scattering processes dominate at temperatures below the Debye temperature ( e . g ., T = 300 K), and thus, non‐uniformities of grain boundaries may be the primary reasons for the decrease in κ at room temperature for 1Ce:YAG 87,88,90 . Our results appear to support the latter hypothesis, although rare‐earth driven acoustic scattering cannot be ruled out.…”

“…% Ce). This has been previously described, 75,87,89,90 and there are two primary hypotheses for this phenomenon. First, the garnet structure possesses several optical-phonon modes which do not contribute to heat transport; thus, the majority of heat dissipation is dictated by acoustic phonons with wave numbers of <125 cm −1 .…”

Multicenter Structure and Dynamical Processes in the Rare Earth Doped Garnet and Sesquioxide Laser Crystals and Ceramics

“…No such effects were observed for the fine-grained ceramics. [58,59] However, there are several major points of concern in this interpretation: first, these observed satellites are much more shifted from the main line N than the satellites M 1 reported previously in the global absorption spectra of crystals and ceramics. Second, as shown by the studies on crystals and ceramics, no luminescence can be observed for the M 1 pairs, even at low temperatures or at very high Nd concentrations (9 at.%).…”

“…[20][21][22][23]59] Fourth, large regions of enhanced C Nd would increase the global concentration of Nd pairs and modify the M satellite structure of the spectra; however, no obvious departure from the predictions of random distribution was observed in the global absorption spectra of these materials, up to high (9 at.% Nd concentrations. Fifth, no obvious lowering of performances of the lasers based on these ceramics compared with those having single crystals and which could be attributed to such large-scale Nd agglomerates was observed.…”

Luminescent Materials Based on Aluminates: A Review

“…[ 17 ] Active‐tip based, near‐field optics are realized by coating a standard tip with Ce 3+ ‐doped YAG particles. [ 234 ] YAG:Ce 3+ nanoparticles attached to biomolecules work as luminescent markers for bioimaging. [ 235,236 ] Ce 3+ –Yb 3+ ‐codoped YAG has been considered as a downconversion phosphor for modifying the solar spectrum.…”