Materials Research Bulletin, Vol.46, No.7, 987-994, 2011
Investigations on the low voltage cathodoluminescence stability and surface chemical behaviour using Auger and X-ray photoelectron spectroscopy on LiSrBO3:Sm3+ phosphor
Orange-red emissive LiSrBo(3):Sm3+ phosphors were synthesized through the solid-state reaction method. Under UV radiation (221 nm) and low-voltage electron beam (2 keV, 12 mA/cm(2)) excitation, the Sm3+ doped LiSrBO3 phosphor shows emission corresponding to the characteristic (4)G(5/2)-H-6(7/2) transitions of Sm3+ with the strongest emission at 601 nm. A high stability of cathodoluminescence (CL) emission during prolong electron bombardment with low-energy electrons was observed. Surface sensitive diagnostic tools such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to study the surface chemistry. AES results revealed modifications in the surface concentrations of Li, Sr, B, O and C on the surface of the LiSrBO3:Sm3+ phosphor as indicated by the changes in their Auger peak to peak heights (APPH) as a function of electron dose. Observed changes in the high resolution XPS spectra of the LiSrBO3:Sm3+ surface irradiated with the low energy electron beam provide evidence of compositional and structural changes as a result of the electron beam stimulated surface chemical reactions (ESSCRs). Additional SrO2 was identified by XPS on the phosphor surface after it received an electron dose of 300 C/cm(2) together with the increase in the concentrations of chemical species containing the B-C-O bonding. The new surface chemical species formed during electron beam bombardment are possibly responsible for the stability of the CL in the LiSrBO3:Sm3+ phosphor. (C) 2011 Elsevier Ltd. All rights reserved.
Keywords:X-ray photoelectron spectroscopy;LiSrBo(3);Cathodoluminescence degradation;Auger electron spectroscopy;ESSCR