High hardnesses of Tm3+-doped La2O3-Al2O3 luminescent glasses fabricated by containerless solidification

A series of colorless and transparent (28-x)La2O3-72Al(2)O(3):xTm(3+) (x = 0, 1, 1.5, 2, 3) luminescent glasses were successfully prepared by the containerless method. The effects of Tm3+ substitution on the physical, thermal, optical and photoluminescence properties of La2O3-Al2O3 glasses were investigated. X-ray diffraction confirmed the amorphous natures of the as-prepared glasses. Excitated at 354 nm, La2O3-Al2O3:Tm3+ glasses emitted blue luminescence at 457 nm, corresponding to the D-1(2) -> F-3(4) transition of Tm3+. These glasses showed high Vicker's hardnesses (7.2-8.8 GPa), and excellent thermal stabilities (T-g : 840-851 degrees C), which were both augmented with increasing content of Tm3+. They also exhibited high transmittances in a wide window ranging from 220 nm to 8.9 pm. In conclusion, the substitution of Tm2O3 for La2O3 increased the Vicker's hardness, thermal stability and transmittance window of La2O3-Al2O3 glasses, allowing potential applications to optical devices in the visible to infrared region.