| Sol–gel synthesis and structural and luminescent characteristics of a Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 polycomponent solid solution |
| Mikhail N. Palatnikov1, Olga B. Shcherbina1, Sofja M. Masloboeva1, Maxim V. Smirnov1, Olga V. Sidorova2, Alexandra V. Kadetova1, Elena V. Zelenina3, Vadim V. Efremov1, Yulia P. Fedorinova2 |
1Tananaev Institute of Chemistry – Subdivision of the Federal Research Centre, Kola Science Centre of the Russian Academy of Sciences, Apatity, Russia
2Petrozavodsk State University, Petrozavodsk, Russia
3V. G. Khlopin Radium Institute, Saint Petersburg, Russia |
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Received: October 5, 2022; Revised: January 20, 2023 Accepted: February 14, 2023. Published online: March 16, 2023. |
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| ABSTRACT |
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In the work, a fine powder of GdNb0.9Ta0.1O4 -mixed gadolinium tantalum niobate activated with rare earth (REE) cations (Sm3+, Eu3+, Tb3+ and Er3+) was obtained by sol–gel synthesis. The evolution of the powder from amorphous to crystalline form was also studied in the work. The evolution was studied by synchronous thermal and X-ray analysis. The phase composition and structure of the resulting Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 powders were analyzed in detail. Ceramic samples of the Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 polycomponent solid solution were prepared from the sol–gel synthesized powder using traditional ceramic technology. The phase composition and characteristics of the structure of individual phases of the Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 ceramic solid solution was determined by full-profile analysis of XRD patterns of polycrystals. We established that incorporation of REE (Tb, Er, Eu, Sm) into the gadolinium site in GdNb0.9Ta0.1O4 solid solution leads to various distortions of the corresponding polyhedra. Note that the distortion degree in this case is much greater than the distortion of the initial GdNbO 4 structure. The photoluminescent (PL) properties of the Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 solid solution were studied in the visible wavelength range. Analysis of literature and our own data revealed: electronic relaxation pathways in Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 ceramics can be different depending on the energy of the exciting radiation. Excitation by the 376 nm line leads to internal energy conversion over 4fn–4fn levels of REE cations (Sm3+, Eu3+, Tb3+ and Er3+). The energy transfer between the Nb4+–O−–Ta4+–O− groups and REE is maximal in this case, while the radiation of the matrix from Nb4+–O−–Ta4+–O− emission centers is minimal. Upon excitation in the near-UV range (376 nm), Gd3+ cations do not participate in the energy transfer between the matrix and 4fn–4fn levels of REE dopants. The maximum PL of Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 ceramics is observed in the green–red region of the spectrum from 5D0–7F2 and 4G5/2–6H7/2 transitions of Eu3+ and Sm3+. The emission is maximal at ~ 612 nm; it corresponds to the 5D0–7F2 electric dipole transition of the Eu3+ cation. We established that the efficiency of energy transfer between the matrix and doping REE cations for Gd0.96Eu0.01Sm0.01Tb0.01Er0.01Nb0.9Ta0.1O4 ceramics strongly depends on the energy of the exciting radiation. |
| Key words:
Gadolinium niobate tantalate · Sol–gel synthesis · Solid solution · Simultaneous thermogravimetric analysis · Full-profi le analysis of XRD patterns · Photoluminescence |
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