resumo
We report that luminescence of Eu3+ ion incorporated into Ruddlesden-Popper phases allows monitoring phase transition in powders (instead of single crystals), in a time-efficient manner (compared to neutron diffraction), and importantly, with greater sensitivity than previous methods. Crystal structure and dielectric response of undoped and 0.5%Eu3+-doped Sr3Sn2O7 ceramics were studied as a function of temperature over the temperature range of 300-800 K. The luminescence studies of 0.5%Eu3+-doped Sr2SnO4 and Sr3Sn2O7 samples were performed in the temperature range of 80-500 K. These results were compared with the respective dependences for the undoped compounds. The structural transformations in 0.5%Eu3+-doped Sr3Sn2O7 were found at 390 and 740 K. The former is associated with the isostructural atomic rearrangement that resulted in a negative thermal expansion along two of three orthorhombic crystallographic axes, while the latter corresponds to the structural transition from the orthorhombic Amam phase to the tetragonal I4/mmm one. A similar temperature behavior with the structural transformations in the same temperature ranges was observed in undoped Sr3Sn2O7, although the values of lattice parameters of the Eu3+-doped and undoped compounds were found to be slightly different indicating an incorporation of europium in the crystal lattice. A dielectric anomaly associated with a structural phase transition was observed in Sr(3)Sn(2)O(7 )at 390 K. Optical measurements performed over a wide temperature range demonstrated a clear correlation between structural transformations in Eu3+-doped Sr2SnO4 and Sr3Sn2O7 and the temperature anomalies of their luminescence spectra, suggesting the efficacy of this method for the determination of subtle phase transformations.
palavras-chave
NEUTRON POWDER DIFFRACTION; BROMATE ENNEAHYDRATE; FERROELECTRICITY; ENERGY; PHOTOLUMINESCENCE; PEROVSKITES; TRANSITIONS; ORIGIN; OXIDES; SERIES
categoria
Chemistry
autores
Stanulis, A; Katelnikovas, A; Salak, AN; Seibutas, P; Ivanov, M; Grigalaitis, R; Banys, J; Kareiva, A; Ramanauskas, R; Barron, AR
nossos autores
Andrei Salak
Investigador Principalagradecimentos
The study was funded from the European Community's social foundation under Grant No. VP1-3.1-SMM-08-K-01-004/KS-120000-1756. The part of this work done in the Univ. of Aveiro was supported by Project TUMOCS. This project has received funding from European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant No. 645660. Additional support was provided by the Flexible Integrated Energy Systems research operation funded by the Welsh European Funding Office through the Welsh Government.