The Photoluminenscence Properties And Preparation Of The Er³⁺ And Er³⁺+Yb³⁺ Doped Al₂O₃ Derived From The Non-aqueous Sol-gel Method

The Er³+ and Er³++Yb³+-doped Al₂O₃ powders and films sintered at the different temperatures were prepared by the non-aqueous sol-gel method. The influence of the doping concentration, the sintering temperature and the coherent effect of Yb³+ on the phase structure and photoluminescence (PL) properties were systematically investigated. The γ-(Al,Er)₂O₃, θ-(Al,Er)₂O₃, α-Al₂O₃, ErAlO₃ and Al₁0Er₆O₂4 phases were detected in the Er³+-doped Al₂O₃ powders. The Er³+ doping suppressed crystallization of the γ and θ phases and delayed phase transitions of the γ→θ and 0→α about 60-110 ℃. The γ and mixture of γ and θ phases were favorite to gain the optimum PL properties, which were improved with the rise in amount of θ phase. The a phase had no effect on the PL properties. The PL spectrum was splitting and the full widths at half maximum (FWHM) became narrow with the appearance of ErAlO₃ and Al₁0Er₆O₂4 phases. The phase transition temperatures of γ→θ and θ→α for Al₂O₃ prepared by the non-aqueous method were increased about 100 and 200 ℃ compared to that prepared by the aqueous method. After doping Er³+, the delay effect induced by doping Er³+ on the phase transition of γ→θ and θ→α for Al₂O₃ prepared by the non-aqueous method was more remarkable than that prepared by the aqueous method. The crystal with column grain was observed for the Er³+-doped Al₂O₃ films prepared by the non-aqueous method. The crystal with anisotropy grain was obtained for that prepared by the aqueous method. The two kinds of Er³+-doped Al₂O₃ films had γ-Al₂O₃ (110) preferred orientation, and the film with the structure of column grain has a more apparent (110) preferred orientation than that of the anisotropy grain. Under the same conditions of Er³+ doping concentration and sintering temperature, the PL intensity centered at 1.53 μm and FWHM of the spectra for the Er³+-doped Al₂O₃ prepared by the non-aqueous method were stronger than that prepared by the aqueous method. The favorable room-temperature PL properties were acquired for the Er³++Yb³+-doped Al₂O₃ films with the ratio of 1:10 prepared by the non-aqueous sol-gel method, which were improved with increasing doping Er³+ concentrations from 0.1 to 1 mol %, and the FWHM were up to 54-57 nm. The phase structures and PL properties of theEr³+-doped powders and films were significantly influenced by the preparation procedure of the sol-gel method.