Enhancement of orange emission of Co2+ ions with Bi3+ ions in lead silicate glasses

Lead silicate glasses mixed with 5.0 mol% of Bi2O3 and doped with varying concentrations of CoO have been synthesized. Optical absorption, infrared and photoluminescence spectra and luminescence decay profiles of the prepared glasses were recorded at ambient temperature. Analysis of IR spectral results have indicated that there is increasing proportion of the tetrahedral Co2+ ions in the glass network with increase in the concentration of CoO. The emission spectra of Bi2O3 free glasses exhibited two significant bands in the orange and red regions when excited at 595 nm. These bands are identified as being due to 4T1(4P)→4A2(4F) and 4T1(4P) →4T2(4F) tetrahedral transitions of Co2+ ion, respectively. The intensity of orange emission band due to 4T1(4P)→4A2(4F) transition is found to be enhanced nearly five times when the glasses are mixed with 5.0 mol% of Bi2O3. The quantitative analysis of these results indicated that the energy transfer from 3P1→ 1S0 emission transition of Bi3+ ions to 4T1(4P)→4A2(4F) tetrahedral transition of Co2+ ion is responsible for the enrichment of this orange emission.