Luminescence and Energy Levels of Mn2+ in LnMB5O10 (Ln=La, Gd and Y; M=Mg, Zn and Cd)

Luminescence of Bi3+ or/and Mn2+ in LnMB5O10 system of phosphor has been studied. Bi3+ in LnMB5O10 leads to two types of emissions, viz. emission due to (i) Bi3+ isolated centres and (ii) Bi3+ clusters. In LaMB5O10, Bi3+ emission can cover longer distances (25 Å) for resonant transfer. In LaMgB5O10, replacement of Mg by Cd or Zn leads to considerable enhancement in Mn2+ emission intensity. In the case of GdMB5O10 system, this substitution leads to significant increase in the Gd3+→Mn2+ energy transfer rate. Energy levels of Mn2+ in LaMB5O10 and crystal field parameters (for the case of cubic field) have been calculated and the results based on these are discussed.