On the investigation of the energy transfer in Ca9Lu(PO4)7:Eu2+,Mn2+,Nd3+

This work deals with Eu2+, Mn2+, and Nd3+ co-activated Ca9Lu(PO4)(7) as luminescent compositions, which were made by high temperature solid-state synthesis upon using rare earth oxides, calcium carbonate, manganese oxalate, and ammonium dihydrogen phosphate as starting materials. Luminescent samples according to Ca9Lu (PO4)(7):Eu2+,Mn2++,Nd3+ comprise Eu2+ for the absorption of radiation in the ultraviolet and blue spectral range (200-450 nm) prior to energy transfer to Mn2+ and Nd3+. The result of the energy transfer between Eu2+, Mn2+, and Nd3+ is the observation of line emission originating from Nd3+ in the near infrared range. The energy transfer between Eu2+, Mn2+, and Nd3+ is discussed via the variations of the emission intensities and lifetime values. The strong absorption of Eu2+ in the ultraviolet and blue spectral range and the efficient energy transfer from Eu2+ to Mn2+ and Nd3+ indicate that the herein presented material type can serve as a radiation converter for white and near infrared emitting diodes (NIR-LEDs) comprising an UV-A emitting (Al,Ga)N chip.