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Title: Ce–O Covalence in Silicate Oxyapatites and Its Influence on Luminescence Dynamics

Abstract

Cerium substituting gadolinium in Ca2Gd8(SiO4)6O2 occupies two intrinsic sites of distinct coordination. The coexistence of an ionic bonding at a 4F site and an ionic–covalent mixed bonding at a 6H site in the same crystalline compound provides an ideal system for comparative studies of ion–ligand interactions. Experimentally, the spectroscopic properties and photoluminescence dynamics of this white-phosphor are investigated. An anomalous thermal quenching of the photoluminescence of Ce3+ at the 6H site is analyzed. Theoretically, ab initio calculations are conducted to reveal the distinctive properties of the Ce–O coordination at the two Ce3+ sites. The calculated eigenstates of Ce3+ at the 6H site suggest a weak Ce–O covalent bond formed between Ce3+ and one of the coordinated oxygen ions not bonded with Si4+. The electronic energy levels and frequencies of local vibrational modes are correlated with specific Ce–O pairs to provide a comparative understanding of the site-resolved experimental results. On the basis of the calculated results, we propose a model of charge transfer and vibronic coupling for interpretation of the anomalous thermal quenching of the Ce3+ luminescence. The combination of experimental and theoretical studies in the present work provides a comprehensive understanding of the spectroscopy and luminescence dynamics of Ce3+ inmore » crystals of ionic–covalent coordination.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1396039
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 118; Journal Issue: 29
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ion-ligand interaction; luminescence quenching; phosphors; vibronic coupling

Citation Formats

Zhai, Dengyun, Ning, Lixin, Huang, Yucheng, and Liu, Guokui. Ce–O Covalence in Silicate Oxyapatites and Its Influence on Luminescence Dynamics. United States: N. p., 2014. Web. doi:10.1021/jp5049293.
Zhai, Dengyun, Ning, Lixin, Huang, Yucheng, & Liu, Guokui. Ce–O Covalence in Silicate Oxyapatites and Its Influence on Luminescence Dynamics. United States. doi:10.1021/jp5049293.
Zhai, Dengyun, Ning, Lixin, Huang, Yucheng, and Liu, Guokui. Thu . "Ce–O Covalence in Silicate Oxyapatites and Its Influence on Luminescence Dynamics". United States. doi:10.1021/jp5049293.
@article{osti_1396039,
title = {Ce–O Covalence in Silicate Oxyapatites and Its Influence on Luminescence Dynamics},
author = {Zhai, Dengyun and Ning, Lixin and Huang, Yucheng and Liu, Guokui},
abstractNote = {Cerium substituting gadolinium in Ca2Gd8(SiO4)6O2 occupies two intrinsic sites of distinct coordination. The coexistence of an ionic bonding at a 4F site and an ionic–covalent mixed bonding at a 6H site in the same crystalline compound provides an ideal system for comparative studies of ion–ligand interactions. Experimentally, the spectroscopic properties and photoluminescence dynamics of this white-phosphor are investigated. An anomalous thermal quenching of the photoluminescence of Ce3+ at the 6H site is analyzed. Theoretically, ab initio calculations are conducted to reveal the distinctive properties of the Ce–O coordination at the two Ce3+ sites. The calculated eigenstates of Ce3+ at the 6H site suggest a weak Ce–O covalent bond formed between Ce3+ and one of the coordinated oxygen ions not bonded with Si4+. The electronic energy levels and frequencies of local vibrational modes are correlated with specific Ce–O pairs to provide a comparative understanding of the site-resolved experimental results. On the basis of the calculated results, we propose a model of charge transfer and vibronic coupling for interpretation of the anomalous thermal quenching of the Ce3+ luminescence. The combination of experimental and theoretical studies in the present work provides a comprehensive understanding of the spectroscopy and luminescence dynamics of Ce3+ in crystals of ionic–covalent coordination.},
doi = {10.1021/jp5049293},
journal = {Journal of Physical Chemistry. C},
number = 29,
volume = 118,
place = {United States},
year = {Thu Jul 24 00:00:00 EDT 2014},
month = {Thu Jul 24 00:00:00 EDT 2014}
}