Luminous efficacy (LE) and colour rendering index (CRI) of various simulated phosphor-converted warm white-light emitting diodes are calculated. Actual measured phosphor emission spectra are employed for this task. The efficacy and CRI of Eu 3+ activated red emitting phosphors are superior to Eu 2+ emitting nitride-based phosphors, however, Eu 3+ suffers from low absorption strength in the blue spectral range.Tb 3+ exhibits comparatively strong absorption in this range and can be used as a sensitizer for Eu 3+ . A solid solution series of (Tb 1Àx Eu x ) 2 Mo 3 O 12 (TM:Eu 3+ ) powders and ceramic discs is prepared by conventional solid state synthesis. Complete transfer from Tb 3+ to Eu 3+ is achieved in the (Tb 0.8 Eu 0.2 ) 2 Mo 3 O 12 sample and a red colour point is realized upon 487 nm (Tb 3+ 7 F 6 / 5 D 4 ) excitation with a quantum efficiency of 94%. Full conversion of a 380 nm LED and improved conversion of a 465 nm LED was achieved employing TM:Eu 3+ ceramics. The position and temperature related shift of the Eu 3+ Stark sublevels is determined from temperature-dependent emission and excitation spectra. These spectra also reveal excited state absorption from thermally excited Eu 3+ 7 F 1 , 7 F 2 and 7 F 3 states. Hightemperature measurements in the range of 350 to 800 K show a T 0.5 of 627 K. Decay measurements exhibit a clearly visible rise time. A new method to determine energy transfer rates from rise time curves is developed. From the energy transfer rates the transfer mechanism and efficiency can be determined with a higher degree of confidence compared to methods based on luminescence intensities.

A series of polycrystalline Li 3 Ba 2 La 3Àx Eu x (MoO 4 ) 8 samples were prepared by the conventional solidstate reaction. The phase formation of the samples was investigated by X-ray diffraction measurements. The luminescence spectra and decay curves were studied as a function of Eu 3+ concentration and temperature. It turned out that the optical band gap of the undoped molybdates is at 3.65 eV. The quantum efficiency (QE) of the Eu 3+ doped luminescent materials increases with increasing Eu 3+ concentration and almost 100% QE was obtained for those samples doped with 70, 80, or 90% Eu 3+ . A sample containing 100% Eu 3+ showed solely a slight decrease in quantum efficiency. The luminous efficacy (LE) was 330 and 312 lm W opt À1 for the 10 and 100% Eu 3+ doped samples, respectively. The decrease of LE values is caused by a slight shift of the colour point to the red spectral range with increasing Eu 3+ content. Temperature dependent measurements revealed that Li 3 Ba 2 Eu 3 (MoO 4 ) 8 loses only 15% of efficiency up to 400 K, which demonstrates that the investigated phosphors are attractive for application in pcLEDs.

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A new blue emitting Eu2+ phosphor with ultra high thermal stability for high CRI near-UV LEDs.