Energy transfer-driven infrared emission processes in rare earth-doped Sc2O3 ceramics

The paper describes the emission decay of levels 4S3/2 of Er3+, 4F3/2 of Nd3+, 3H4 of Tm3+ and 5D4 of Tb3+ in heavily doped (up to 10%Nd, 10%Er, 5%Tm) sesquioxide ceramics and the infrared emission under visible or near infrared in these systems. For the Er, Nd or Tm ceramics at high concentrations a new energy transfer down-conversion process occurs that shows the characteristics (temporal and concentration dependence) of cooperative de-excitation. The implication of the doping ions from the two structural sites of sesquioxides in the down-conversion processes is discussed.