TY - JOUR

T1 - Microstructure, doping and optical properties of Co2+:ZnAl2O4 transparent ceramics for saturable absorbers

T2 - Effect of the ZnF2 sintering additive

AU - Belyaev, Alexander

AU - Basyrova, Liza

AU - Sysoev, Vadim

AU - Lelet, Maxim

AU - Balabanov, Stanislav

AU - Kalganov, Vladimir

AU - Mikhailovski, Vladimir

AU - Baranov, Mikhail

AU - Stepanidenko, Evgeniia

AU - Vitkin, Vladimir

AU - Dymshits, Olga

AU - Loiko, Pavel

PY - 2020/7/15

Y1 - 2020/7/15

N2 - Transparent cobalt-doped zinc aluminate spinel (gahnite), Co2+:ZnAl2O4, ceramics were fabricated by hot pressing of (Zn,Co)Al2O4/ZnF2 nanopowders at 1520 °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 °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 μm and high in-line transmission (about 84% at ∼2 μm). The actual concentration of Co2+ ions in tetrahedral (Td) 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 (Oh) sites of gahnite due to its partly inverse spinel structure. The developed ceramics are promising for saturable absorbers of erbium lasers.

AB - Transparent cobalt-doped zinc aluminate spinel (gahnite), Co2+:ZnAl2O4, ceramics were fabricated by hot pressing of (Zn,Co)Al2O4/ZnF2 nanopowders at 1520 °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 °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 μm and high in-line transmission (about 84% at ∼2 μm). The actual concentration of Co2+ ions in tetrahedral (Td) 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 (Oh) sites of gahnite due to its partly inverse spinel structure. The developed ceramics are promising for saturable absorbers of erbium lasers.

KW - Cobalt ions

KW - Gahnite

KW - Hot pressing synthesis

KW - Microstructure

KW - Saturable absorbers of lasers

KW - Sintering additive

KW - Transparent ceramics

KW - SUBLIMATION

KW - EXCITED-STATE ABSORPTION

KW - GLASS-CERAMICS

KW - ZINC

KW - TETRAHEDRAL CO2+

KW - LUMINESCENCE

KW - DIELECTRIC-PROPERTIES

KW - CATION DISTRIBUTION

KW - FABRICATION

KW - SPECTRA

UR - http://www.scopus.com/inward/record.url?scp=85080938969&partnerID=8YFLogxK

U2 - 10.1016/j.jallcom.2020.154514

DO - 10.1016/j.jallcom.2020.154514

M3 - Article

AN - SCOPUS:85080938969

VL - 829

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

SN - 0925-8388

M1 - 154514

ER -