ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The addition of oxygen in Ca0.5Sr0.5Ga2S4:Ce phosphor was found to nearly double the luminance and to blue shift the emission spectrum of the Ce+3 4f–5d transition. X-ray photoelectron spectroscopy (XPS) analysis was used to investigate the local chemistry of the Ce+3 luminescent center in the undoped and oxygen-doped Ca0.5Sr0.5Ga2S4 phosphor. The shake up structure in the Ce+3 3d3/2 and 3d5/2 XPS spectra is due to a ligand-to-metal charge transfer process, and the relative intensity of the charge transfer peaks increased when oxygen was introduced. Because the charge transfer probability is controlled by the local ionicity of the Ce bonds, the increase in the charge transfer peak intensity is consistent with the formation of Ce–O bonds. Furthermore, the binding energy of the charge transfer peaks and the Ce MNN Auger peak shifted, again consistent with oxygen bonding to the Ce+3 luminescent center. A self-consistent field configuration interaction model is used to calculate the positions of the 4f and 5d levels with Ce–S and Ce–O bonds. By replacing the three of eight sulfur ligands with oxygen the SCF/CI model predicted a 1035 cm−1 blue shift in the 4f–5d transition energy which was in excellent agreement with the observed 730 cm−1 blue shift. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.371063
