well as the relative integrated band intensities I(2E)/I(4T2) (or
I(2E)/ITOTAL) decrease indicating tendency to lower crystal field
with increasing PbO content, which was evidenced by Gaussian
fitting procedure.
2. The R and Y/B values due to 5D0–7F2/5D0–7F1 and 4F9/2– 6H15/2/4F9/2–6H13/2 luminescence intensity ratios of Eu3+ and
Dy3+, respectively, increase with increasing heavy metal
(PbO) content, suggesting higher asymmetry and more covalent
bonding character between rare earth and oxygen
ions