Journal of Advanced Ceramics (Aug 2024)
Nd3+:YAG–Al2O3 nanocrystalline transparent ceramics with high inflexion concentration quenching of Nd3+ prepared by amorphous crystallization
Abstract
Rare earth ion-doped Y3Al5O12 (YAG)-based transparent ceramics have been used as important laser gain media for a long time, yet the doping concentration of active ions is limited due to concentration quenching, wherein the inflexion concentration quenching of Nd3+ is recognized as 1.0 at%. In this work, YAG–Al2O3 nanocrystalline transparent ceramics with a concentration of Nd3+ (0–5.0 at%) were fabricated via amorphous crystallization, and the crystal structure evolution, morphology, and optical properties were systematically investigated by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), magnetic resonation (MAS), nuclear magnetic resonation (NMR), and fluorescence spectroscopy. The doping of Nd3+ can promote the transition of Al[5] and Al[6] to Al[4], indicating improvements in the ability of the amorphous material to form Nd3+:Y2O3–Al2O3 vitrified beads, and 1.5 at% Nd3+:YAG–Al2O3 nanocrystalline transparent ceramics can be obtained by crystallization at 1050 °C with a matrix composed of YAG and concomitant δ-Al2O3 and θ-Al2O3. The nanocrystalline transparent ceramics show an internal transmittance of 89.56% at 1064 nm, and the strongest emission peak corresponds to the energy transfer from 4F3/2 to 4I11/2 of Nd3+ with a fluorescence lifetime of 231 μs when pumped by an 808 nm laser. Specifically, spectral broadening begins to occur, indicating the onset of concentration quenching, when the concentration of Nd3+ exceeds 1.5 at%, substantially higher than the 1.0 at% observed in YAG ceramics. YAG–Al2O3 nanocrystalline transparent ceramics obtained by amorphous crystallization can be utilized as the matrix to increase the inflexion point of doping concentration quenching of Nd3+, and this material may have great potential as a laser gain medium.
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