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An EXAFS study on europium doped calcium thiosilicates

Katleen Korthout (UGent) , Anthony Parmentier (UGent) , Philippe Smet (UGent) and Dirk Poelman (UGent)
Author
Organization
Abstract
Europium doped calcium thiosilicates are currently being investigated for use in phosphor converted light-emitting diodes (pc-LEDs), due to their efficient yellow-to-red emission. Their emission spectrum consists of two separate broad emission bands, which are caused by 4f65d→4f7 transitions of the Eu2+ ions, in combination with the presence of two inequivalent lattice sites for Eu2+. Hereby, the emission spectrum and the crystal structure are highly dependent on the europium concentration. Unfortunately no direct investigation of the dopants incorporation was performed yet. We combined X-ray absorption fine structure and photoluminescence measurements to analyze the structure of Eu centers in Ca2SiS4:Eu powder samples. This work aims at an explanation for the concentration dependencies of the emission spectra. We find that data can be understood on the basis of a model involving two kinds of Eu centers substituting for Ca ions: (i) Eu ions that are arranged in rows, the dominant center (S1) and (ii) Eu ions that substitute the second Ca site not forming a row or chain (S2). The occupancies of both types of centers are determined from the x-ray absorption data at the Eu-LIII edge obtained at the DUBBLE-BM26 beamline (ESRF, Grenoble, France). Two characteristic emission bands peaking at about 564 and 660 nm are attributed to (S2) and (S1) respectively. Summarizing, the influence of the concentration on the emission spectrum is related to different occupancies of the two kinds of Eu centers in the calcium thiosilicates.
Keywords
thiosilicate, europium, EXAFS

Citation

Please use this url to cite or link to this publication:

MLA
Korthout, Katleen, Anthony Parmentier, Philippe Smet, et al. “An EXAFS Study on Europium Doped Calcium Thiosilicates.” Synchrotron and Neutron Workshop, Abstracts. 2011. Print.
APA
Korthout, K., Parmentier, A., Smet, P., & Poelman, D. (2011). An EXAFS study on europium doped calcium thiosilicates. Synchrotron and Neutron Workshop, Abstracts. Presented at the Synchrotron and Neutron Workshop (SyNeW 2011).
Chicago author-date
Korthout, Katleen, Anthony Parmentier, Philippe Smet, and Dirk Poelman. 2011. “An EXAFS Study on Europium Doped Calcium Thiosilicates.” In Synchrotron and Neutron Workshop, Abstracts.
Chicago author-date (all authors)
Korthout, Katleen, Anthony Parmentier, Philippe Smet, and Dirk Poelman. 2011. “An EXAFS Study on Europium Doped Calcium Thiosilicates.” In Synchrotron and Neutron Workshop, Abstracts.
Vancouver
1.
Korthout K, Parmentier A, Smet P, Poelman D. An EXAFS study on europium doped calcium thiosilicates. Synchrotron and Neutron Workshop, Abstracts. 2011.
IEEE
[1]
K. Korthout, A. Parmentier, P. Smet, and D. Poelman, “An EXAFS study on europium doped calcium thiosilicates,” in Synchrotron and Neutron Workshop, Abstracts, Amsterdam, The Netherlands, 2011.
@inproceedings{3049621,
  abstract     = {Europium doped calcium thiosilicates are currently being investigated for use in phosphor converted light-emitting diodes (pc-LEDs), due to their efficient yellow-to-red emission. Their emission spectrum consists of two separate broad emission bands, which are caused by 4f65d→4f7 transitions of the Eu2+ ions, in combination with the presence of two inequivalent lattice sites for Eu2+. Hereby, the emission spectrum and the crystal structure are highly dependent on the europium concentration. Unfortunately no direct investigation of the dopants incorporation was performed yet. We combined X-ray absorption fine structure and photoluminescence measurements to analyze the structure of Eu centers in Ca2SiS4:Eu powder samples. This work aims at an explanation for the concentration dependencies of the emission spectra. We find that data can be understood on the basis of a model involving two kinds of Eu centers substituting for Ca ions: (i) Eu ions that are arranged in rows, the dominant center (S1) and (ii) Eu ions that substitute the second Ca site not forming a row or chain (S2). The occupancies of both types of centers are determined from the x-ray absorption data at the Eu-LIII edge obtained at the DUBBLE-BM26 beamline (ESRF, Grenoble, France). Two characteristic emission bands peaking at about 564 and 660 nm are attributed to (S2) and (S1) respectively. Summarizing, the influence of the concentration on the emission spectrum is related to different occupancies of the two kinds of Eu centers in the calcium thiosilicates.},
  author       = {Korthout, Katleen and Parmentier, Anthony and Smet, Philippe and Poelman, Dirk},
  booktitle    = {Synchrotron and Neutron Workshop, Abstracts},
  keywords     = {thiosilicate,europium,EXAFS},
  language     = {eng},
  location     = {Amsterdam, The Netherlands},
  title        = {An EXAFS study on europium doped calcium thiosilicates},
  year         = {2011},
}