The influence of morphology of starting Al2O3 nanopowders on the microstructure and optical properties of YAG:Sm3+ ceramics

DOI: 10.62564/M4-АТ2116

Arsenii Tymoshenko, Oxana Matvienko, Sergey Parkhomenko, Ihor Vorona, Alexander Tolmachev, Roman Yavetskiy

Institute of Single Crystals of the National Academy of Sciences of Ukraine


YAG:Sm3+ transparent ceramics is considered as a promising material for suppressors of amplified emission of powerful YAG:Nd3+ lasers. One of the main tasks during production of optical ceramics is to control the sintering trajectory towards high-density final state, i.e. to ensure that densification mechanisms prevail over recrystallization. To obtain a polycrystalline material with specified properties, it is necessary to control the morphology of the starting powders, the impurity composition of ceramics, and consolidation conditions during sintering. The structural and morphological properties of the powders used as starting materials determine the mesostructure of compacts, i.e. the starting point of the sintering trajectory, and are the first critical parameter that needs to be optimized during synthesis of optical ceramics. The purpose of this work was to study the influence of the morphology of the initial Al2O3 nanopowders on the microstructure and optical properties of YAG:Sm3+ ceramics obtained by reactive sintering. YAG:Sm3+ ceramics were synthesized from high-purity commercial α-Al2O3 powders (>99.99%, d=0.15-0.4 μm); Y2O3 (99.999%, d≈5 μm) and Sm2O3 (>99.99%, d=5 μm) by vacuum sintering at 1725°C. To remove residual stresses and restore oxygen vacancies, the ceramics were annealed in air at 1400°C within 15 hours. The effect of particle size composition and morphology of Al2O3 nanopowders on densification efficiency, microstructure and optical properties of YAG:Sm3+ ceramics was studied. It is shown that powder mixtures with uniform particle size distribution provide an optimal sintering trajectory and more effective removal of residual pores compared to powder mixtures with bimodal particle distribution. YAG:Sm3+ ceramics with an average grain size of 25 μm and an in-line optical transmittance as high as 83% at a wavelength of 1064 nm were obtained by the reactive sintering method.

Keywords
YAG, CERAMIC, CONSOLIDATION, MICROSTRUCTURE, NANOPOWDER

Acknowledgments
Not provided

References
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