Radiative properties of 'intense' red emitting LiAl5O8:Eu phosphors

LiAl5O8 doped with varying concentrations of Eu were synthesized by a solid state reaction route. Phase purity of the prepared phosphors was determined using X-ray diffraction technique. Dynamic light scattering technique was used to estimate the average particle size of the synthesized products that was found to be 110 nm. The doped phosphor samples exhibited strong excitation band in the range 210-290 nm with 613 nm emission suggesting the stabilisation of trivalent Eu. With 394 nm (UV) excitation, strong visible luminescence was observed at 613 nm corresponding to the D-5(0) -> F-7(2) transition of the Eu3+ ions. The emission parameters were optimised by varying the dopant ion concentration and annealing temperature. The intensity parameters (abroken vertical bar(lambda), lambda = 2, 4 and 6), radiative transition probabilities (A (R) ), radiative lifetime (tau (R) ) and branching ratios (beta) for the system were evaluated in the framework of the model given by Judd-Ofelt. The CIE coordinates for the system were evaluated by adopting standard procedure, which suggested that the system has enough potential to be used as a red phosphor.