Dynamics of Yb2+ to Yb3+ ion valence transformations in Yb:YAG ceramics used for high-power lasers

• Published in: Optical materials 2020-03, Vol.101, p.109774, Article 109774
• Main Authors: Chaika, Mykhailo, Vovk, Oleh, Mancardi, Giulia, Tomala, Robert, Strek, Wiesław
• Format: Article
• Language: English
• Subjects: Optical ceramics; Oxidation kinetics; Yb:YAG
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2020.109774

Due to the good thermal-mechanical and luminescence properties, Yb:YAG ceramics are suitable as thin-disk lasers; however, their efficiency is limited by the presence of Yb2+ ions, which entail parasitic energy transfer from Yb3+ to Yb2+. This article focuses on the Yb2+ formation in Yb:YAG ceramics prepared by solid-state reaction sintering. The samples were prepared by air annealing, the oxidation of the material leads to recharging Yb2+ ion to its trivalent state. The activation energy was determined by Jander to be Ea(D) = 2.7 ± 0.2 eV, which is in good agreement with the activation energy for oxygen diffusion in the YAG lattice. It was concluded that the recharging of Yb2+ ion to its trivalent state in YAG ceramics is limited by the oxygen self-diffusion through the grain volume, and the oxygen vacancy alone and/or together with the presence of antisites can be proposed as Yb2+ charge compensation mechanism in the YAG ceramics, unlike the YbAG single crystals, where tetravalent impurities are responsible for charge compensation. •The activation energy was determined by Jander to be Ea(D) = 2.7 ± 0.2 eV.•The recharging of Yb2+ ion to Yb3+ ion in YAG ceramics is limited by the oxygen self-diffusion through the grain volume.•The oxygen vacancy alone and/or with the antisites can be proposed as Yb2+ charge compensation mechanism in the YAG ceramics.