The effect of silica doping on neodymium diffusion in yttrium aluminium garnet ceramics : implications for sintering mechanisms

Abstract : The Nd3+ cation diffusion into transparent polycrystalline YAG (Y3Al5O12) was investigated as a function of temperature and silica content. Thin neodymium oxide layers were deposited on sintered YAG substrates prior to annealing under air at temperatures from 1400 to 1600 ◦C. Bulk and grain boundary neodymium diffusion coefficients were measured by secondary ion mass spectrometry. The experimental results show that silica addition increases the diffusivity of Nd3+ by a factor 10 whatever the diffusion path, probably as a result of extrinsic point defects formation, especially rare-earth vacancies. The experimental diffusion data were used to elucidate the sintering mechanism of Nd:YAG ceramics in the temperature range 1450–1550 ◦C. Firstly, it appeared that the intermediate stage of solid-state sintering should be controlled by the rare-earth diffusion along the grain boundary with an activation energy of about 600 kJ mol−1. Secondly, grain growth mechanism at the final stage of liquid-phase sintering was investigated for silica-doped Nd:YAG samples. Thus, the grain growth should be limited by the reaction at interfaces at a temperature lower than 1500 ◦C, with an activation energy of about 880 kJ mol−1. At higher temperature, it seems to be limited by the ionic diffusion through the intergranular liquid phase, with an activation energy of 250 kJ mol−1.
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https://hal.archives-ouvertes.fr/hal-00395919
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Submitted on : Tuesday, June 16, 2009 - 4:11:13 PM
Last modification on : Wednesday, February 14, 2018 - 4:02:09 PM

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Rémy Boulesteix, Alexandre Maitre, Jean-François Baumard, Y. Rabinovitch, C. Salle, et al.. The effect of silica doping on neodymium diffusion in yttrium aluminium garnet ceramics : implications for sintering mechanisms. Journal of the European Ceramic Society, Elsevier, 2009, 29, pp.2517-2526. ⟨10.1016/j.jeurceramsoc.2009.03.003⟩. ⟨hal-00395919⟩

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