Luminescent Eu3+ doped Al6Ge2O13 crystalline compounds obtained by the sol gel process for photonics

We synthesized pure and Eu 3 doped Al 6 Ge 2 O 13 samples by an easy and low-cost sol-gel route using the GeO 2 , Al(NO 3 ) 3 $9H 2 O and Eu(NO3) 3 $6H 2 O as precursors, tetramethylammonium hydroxide and ethanol as solvents. The Al 6 Ge 2 O 13 crystalline phase possesses orthorhombic structure and is a potential host for rare earth ions, especially due to high aluminum concentration. Homogeneous and transparent sols and gels were obtained. The samples containing 1 mol% of Eu 3 were heat-treated at 1000 C to eliminate organic compounds, providing high optical quality and structural purity. All materials were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, selected area electron diffraction, diffuse reflectance spectra in the ultravioletevisibleenear infrared regions and photoluminescence measurements. High purity of Eu 3 doped Al 6 Ge 2 O 13 orthorhombic phase and well crystallized grain dimensions of around 100 nm was obtained with high red photoluminescence emission. The decay lifetime of 5 D 0 level from Eu 3 (the emission at 612 nm) was determined, being between 0.97 and 2.12 ms, and an average quantum efficiency of 54% was determined (considering the average experimental lifetime of 1.77 ms). Moreover, it was calculated and analyzed some parameters of Judd-Ofelt theory applied to Eu 3 emissions from Al 6 Ge 2 O 13 host. The results show that Eu 3 doped Al 6 Ge 2 O 13 crystalline compounds have large potential to be used in displays and LED devices.