TY - JOUR

T1 - Valence state conversion of Mn ions in Li2O–ZnO-GeO2 glass-ceramics: Spectral, structural, ESR and XRF studies

AU - Kulpina, Ekaterina

AU - Babkina, Anastasiia

AU - Zyryanova, Ksenia

AU - Kuzmenko, Natalia

AU - Ignatiev, Alexander

AU - Valiev, Damir

AU - Stepanov, Sergey

AU - Pankin, Dmitrii

AU - Povolotckaia, Anastasia

AU - Platonova, Natalia

AU - Shendrik, Roman

PY - 2024/6/1

Y1 - 2024/6/1

N2 - Lithium-zinc-germanate glass-ceramics doped with Mn ions are synthesized by volume crystallization method. Structural studies show nucleation of different forms of lithium germanate crystals depending on the isothermal treatment regime of the initial glass. With the increase of the heat treatment temperature and the lithium content in the initial glass, the [GeO4] /[GeO6] ratio in the nucleated crystalline phases increases. The initial distribution of Mn2+/Mn3+/Mn4+ is defined by the Li2O/ZnO ratio in the glass composition: the ratio growth increases the contribution of Mn4+ over the Mn2+ and Mn3+. Low-temperature heat treatment of initial glass leads to uprise of intense red emission of Mn4+ ions in the octahedral environment. High-temperature heat treatment leads to occurrence of intense green emission related to Mn2+ ions in a tetrahedral environment. Discussions on all transformations of symmetry, the crystal field strength of Mn ions’ environment and their valence state based on the results of optical spectroscopy, ESR and XRF studies are provided. The maximum quantum yield of red luminescence is 61%, and of green luminescence is 23%. The synthesized glass-ceramics can be used as a luminescent converter of the UV LED radiation with the maximum energy efficiency of 20%.

AB - Lithium-zinc-germanate glass-ceramics doped with Mn ions are synthesized by volume crystallization method. Structural studies show nucleation of different forms of lithium germanate crystals depending on the isothermal treatment regime of the initial glass. With the increase of the heat treatment temperature and the lithium content in the initial glass, the [GeO4] /[GeO6] ratio in the nucleated crystalline phases increases. The initial distribution of Mn2+/Mn3+/Mn4+ is defined by the Li2O/ZnO ratio in the glass composition: the ratio growth increases the contribution of Mn4+ over the Mn2+ and Mn3+. Low-temperature heat treatment of initial glass leads to uprise of intense red emission of Mn4+ ions in the octahedral environment. High-temperature heat treatment leads to occurrence of intense green emission related to Mn2+ ions in a tetrahedral environment. Discussions on all transformations of symmetry, the crystal field strength of Mn ions’ environment and their valence state based on the results of optical spectroscopy, ESR and XRF studies are provided. The maximum quantum yield of red luminescence is 61%, and of green luminescence is 23%. The synthesized glass-ceramics can be used as a luminescent converter of the UV LED radiation with the maximum energy efficiency of 20%.

KW - Divalent manganese

KW - ESR

KW - Luminescent glass-ceramics

KW - Red-to-green conversion

KW - Tetravalent manganese

KW - XRF

UR - https://www.mendeley.com/catalogue/823ab70e-5377-314e-957b-82f562c2f035/

U2 - 10.1016/j.ceramint.2024.03.076

DO - 10.1016/j.ceramint.2024.03.076

M3 - Article

VL - 50

SP - 19592

EP - 19603

JO - Ceramics International

JF - Ceramics International

SN - 0272-8842

IS - 11

ER -