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Electronic Structure and Associated Optical Properties of LAPO4:Ce

Published online by Cambridge University Press:  21 February 2011

K. C. Mishra
Affiliation:
Central Research, OSRAM SYLVANIA INC., 100 Endicott Street, Danvers, MA 01923
K. H. Johnson
Affiliation:
Department of Materials Science, Massachusetts Institute of Technology, Cambridge, MA 02139
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Abstract

Lanthanum phosphate activated by cerium and terbium is a well known lamp phosphor which is used for its green emission. In this paper, we have investigated the electronic structure and associated optical properties of lanthanum phosphate doped with cerium using the self consistent field scattered wave molecular orbital cluster approach. Relativistic corrections are included for the lanthanum and cerium centered clusters. In spite of the small magnitude of crystal field splitting, a significant admixture of the f-like orbitals with the ligand orbitals is observed for cerium. The optical transitions are calculated using the transition state formalism. The absorption peaks due to electronic transition from the f-like states to d-like states of cerium are found to be 271 rim, 259 nm, 245 nm, 208 nm and 194 nm which are in good agreement with the experiment. The nature of the band gap transition in lanthanum phosphate is also discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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References

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