Optical properties of TAG co-doped with Ce and Eu

Nanopowder samples of terbium aluminum garnet (TAG) doped with Ce and Eu were prepared by a sol–gel technique followed by sintering in air at various temperatures (maximum of $$1100{^\circ }\hbox {C}$$). The investigated concentrations of both the dopants were 0.1, 0.5 and 1.0 mol%. Nine powder samples prepared by the permutation of the doping concentrations were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), powder X-ray diffraction (XRD) and optical spectroscopic techniques. SEM and TEM investigations confirmed the nano-structure of the prepared powders while EDX not only confirmed the doping of Ce and Eu in TAG but also eliminated the possibility of any interfering impurities. Powder XRD showed that the basic structure of TAG did not change on doping which was further confirmed by Fourier-transform infrared studies. However, optical absorption and Raman scattering investigations showed the distortion of the TAG lattice on doping. Emission (photoluminescence) in the spectral region of 400–700 nm was observed when excited by 280 nm radiation. The intensity of this emission showed interesting dopant concentration dependence. The emission from TAG co-doped with 0.5 mol% of both Ce and Eu is of particular interest as its calculated colour chromaticity coordinates ‘x and y’ were found as $$x = 0.35$$ and $$y = 0.35$$ which are very close to that of sun light at noon indicating its potential as a material for the white light source.