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Spectroscopic Properties of Eu 3+ Ions in Sol–Gel Materials Containing Calcium Fluoride Nanocrystals
Author(s) -
Pawlik Natalia,
Szpikowska-Sroka Barbara,
Goryczka Tomasz,
Pisarski Wojciech A.
Publication year - 2020
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201900478
Subject(s) - photoluminescence , materials science , nanocrystal , luminescence , sol gel , amorphous solid , silicate , analytical chemistry (journal) , ion , ceramic , infrared spectroscopy , mineralogy , inorganic chemistry , chemical engineering , crystallography , chemistry , nanotechnology , composite material , organic chemistry , optoelectronics , engineering
In this study, a series of Eu 3+ ‐doped silicate xerogels with modified initial compositions is prepared and heat treated at 350 °C to fabricate glass‐ceramic materials containing CaF 2 nanocrystals. The impact of an N , N ‐dimethylformamide (DMF) additive and a catalyst agent (CH 3 COOH, HNO 3 ) on the sol–gel transformation from liquid sols through silicate gels and xerogels into glass‐ceramics is investigated using infrared spectroscopy. To verify the formation of CaF 2 nanocrystals, X‐ray diffraction (XRD) measurements are performed. The optical behavior of Eu 3+ ions in the prepared sol–gel materials is evaluated based on photoluminescence excitation (PLE) and photoluminescence emission (PL) spectra as well as luminescence decay analysis. The distribution of Eu 3+ ions between the amorphous silicate hosts and CaF 2 nanocrystals in the prepared glass‐ceramic samples is found due to the biexponential character of registered decay curves. In addition, R/O‐ratio (R/O is defined as ratio I(D5 0 ‐F7 2 )/I(D5 0 ‐F7 1 ) analysis is conducted to characterize the efficiency of Eu 3+ ion migration into precipitated CaF 2 nanocrystals. The lack of DMF as well as HNO 3 as a catalyst in the initial composition significantly promotes the incorporation of Eu 3+ ions into CaF 2 nanocrystals, resulting in long‐lived luminescence with an estimated lifetime τ (D5 0 ) = 12.84 ms.