Microstructure, doping and optical properties of Co2+:ZnAl2O4 transparent ceramics for saturable absorbers: Effect of the ZnF2 sintering additive

JOURNAL OF ALLOYS AND COMPOUNDS

卷:829

Article

Belyaev, Alexander¹  Basyrova, Liza²  Sysoev, Vadim³  Lelet, Maxim⁴  Balabanov, Stanislav¹  Kalganov, Vladimir⁵  Mikhailovski, Vladimir⁵  Baranov, Mikhail²  Stepanidenko, Evgeniia²  Vitkin, Vladimir²  Dymshits, Olga⁶  Loiko, Pavel⁷ 

[1] RAS, GG Devyatykh Inst Chem High Pur Subst, 49 Tropinin St, Nizhnii Novgorod 603951, Russia

[2] ITMO Univ, Kronverkskiy Pr 49, St Petersburg 197101, Russia

[3] Lobachevsky State Univ Nizhny Novgorod, 23 Gagarin Ave, Nizhnii Novgorod 603950, Russia

[4] Lobachevsky State Univ Nizhny Novgorod, Res Inst Chem, 23 Gagarin Ave, Nizhnii Novgorod 603950, Russia

[5] St Petersburg State Univ, 7-9 Univ Skaya Emb, St Petersburg 199034, Russia

[6] Vavilov State Opt Inst, 36 Babushkina St, St Petersburg 192171, Russia

[7] Univ Caen Normandie, Ctr Rech Ions Mat & Photon CIMAP, CEA CNRS ENSICAEN, UMR 6252, 6 Blvd Marechal Juin, F-14050 Caen 4, France

关键词: Transparent ceramics;    Hot pressing synthesis;    Sintering additive;    Gahnite;    Cobalt ions;    Microstructure;    Saturable absorbers of lasers;   

DOI  :  10.1016/j.jallcom.2020.154514

来源: Elsevier

【 摘 要 】

Transparent cobalt-doped zinc aluminate spinel (gahnite), Co2+:ZnAl2O4, ceramics were fabricated by hot pressing of (Zn,Co)Al2O4/ZnF2 nanopowders at 1520 degrees C for 4 h. A novel approach was suggested for the preparation of (Zn,Co)Al2O4 precursor: the (Zn,Co)Al2O4 powders were synthesized by mixing an alcohol solution of aluminium isopropoxide with a joint aqueous solution of zinc formate (the source of zinc), cobalt nitrate and zinc fluoride (the sintering additive) followed by drying and calcination in air. The study of the thermal behavior of precursors revealed an optimum calcination temperature (700 degrees C) preventing the loss of the sintering additive (ZnF2). The effect of the ZnF2 content (3-10 wt%) on the microstructure, the cobalt doping concentration, absorption and luminescence of ceramics was systematically studied. The ceramics exhibit a close-packed microstructure with a mean grain size of 50-70 mu m and high in-line transmission (about 84% at similar to 2 mu m). The actual concentration of Co2+ ions in tetrahedral (T-d) sites of gahnite is lower than the Co2+ doping level and it decreases with the ZnF2 content. We propose a possible mechanism of this variation including both the losses of Co2+ via evaporation of the intermediate CoF2 phase and a partial location of Co2+ ions in octahedral (O-h) sites of gahnite due to its partly inverse spinel structure. The developed ceramics are promising for saturable absorbers of erbium lasers. (C) 2020 Elsevier B.V. All rights reserved.

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