Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study

Abstract

We describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu(3+) doped, transparent, oxyfluoride glass and nanostructured glass-ceramic samples. The spectra were measured at the Pb and Eu-L(III) edges. The Eu environment in the glass samples is observed to be similar to that of EuF(3). Complementary x-ray diffraction experiments show that thermal annealing creates β-PbF(2) type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb-L(III) edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form β-PbF(2) type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass-ceramic synthesis in order to further improve their properties.

Eu3+-Doped ZnB2O4 (B = Al3+, Ga3+) Nanospinels: An Efficient Red Phosphor

“…The small shift may arise from symmetry breaking or disorder at the Eu­(III) O h site in the Ga spinel. Similar observations have been made for the shift in the W L 3 edge in CaWO 4 . The disorder likely reflects the size difference for Al vs Ga compared to the substitutional Eu­(III) ion.…”

“…In the nanospinel samples, a decrease in the ratio of 5 D 1 → 7 F 1 to 5 D 0 → 7 F 3 is also observed with increasing Eu concentration, which reflects the increasing Eu–Eu interactions in the nanospinel samples (Supporting Information Figures SF6–SF8). The XAS data can be interpreted as supporting this conclusion, as an additional absorption feature would arise in the XANES spectra if clustering of the Eu ions occurs …”

“…Similar observations have been made for the shift in the W L 3 edge in CaWO 4 . 19 The disorder likely reflects the size difference for Al vs Ga compared to the substitutional Eu(III) ion. Consistent with the agreement of disorder, the rounding of the second has been interpreted as distortion of the Eu(III) site symmetry in Eu(II)-doped silicate glasses.…”

Structural Studies of Aluminated form of Zeolites—EXAFS and XRD Experiment, STEM Micrography, and DFT Modelling

“…A series of XAS µ(E) spectra for all samples has been recorded, see Figure 5, and in order to find the proper Al site distribution, Fourier transform (FT) analysis of µ(E) was performed to obtain χ(r). The latter spectra can be regarded as the "pseudo-radial distribution function" [85]. The absolute value of the complex spectra, |χ(r)|, is discussed further in this text.…”

X-ray nanoimaging of Nd^3+ optically active ions embedded in Sr_05Ba_05Nb_2O_6 nanocrystals

“…Previous reports confirmed the inclusion of the RE 3+ ions into the SBN nanocrystals by monitoring the emissions of Nd 3+ at 900 nm and Er 3+ ions at 1550 nm in the glass-ceramic compared to those of the precursor glass. About 75% of the RE 3+ ions were incorporated in the SBN nanocrystals [13,14], probably playing the role of heterogeneous nucleating agents as in other glass-ceramics [15]. However, further studies with nanoscale spatial resolution are necessary in order to elucidate the real distribution of SBN nanocrystals.…”