Infrared emissions, visible up-conversion, thermoluminescence and defect centres in Er3Al5O12 phosphor obtained by solution combustion reaction

The Er3Al5O12 phosphor powders were prepared using the solution combustion method. Formation and homogeneity of the Er3Al5O12 phosphor powders have been verified by X-ray diffraction and energy-dispersive X-ray analysis respectively. The frequency up-conversion from Er3Al5O12 phosphor powder corresponding to the H-2(9/2) -> I-4(15/2), H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), F-4(9/2) -> I-4(15/2) and the infrared emission (IR) due to the I-4(13/2) -> I-4(15/2) transitions lying at similar to 410, similar to 524, similar to 556, 645-680 nm and at similar to 1.53 mu m respectively upon excitation with a Ti-Sapphire pulsed/CW laser have been reported. The mechanism responsible for the frequency up-conversion and IR emission is discussed in detail. Defect centres induced by radiation were studied using the techniques of thermoluminescence and electron spin resonance. A single glow peak at 430A degrees C is observed and the thermoluminescence results show the presence of a defect center which decays at high temperature. Electron spin resonance studies indicate a center characterized by a g-factor equal to 2.0056 and it is observed that this center is not related to the thermoluminescence peak. A negligibly small concentration of cation and anion vacancies appears to be present in the phosphor in accordance with the earlier theoretical predictions.