Effect of ZrO2 and TiO2 on the micro-structure and NIR luminescence of mullite type Cr:Al4B2O9 glass ceramics.

Boron-mullites are potential candidate crystal phases for broadband near-infrared (NIR) luminescence in the mullite series due to their higher complexity in crystal structure and abundant [AlO 6 ] units for accommodating transition metal ions as luminescence activators. In this work, the effect of ZrO 2 and TiO 2 on the microstructure and NIR luminescent properties of mullite type Cr3+:Al 4 B 2 O 9 glass ceramics were analyzed in detail. Through characterizations including XRD, SEM, TEM and NMR, the oriented growth of strip-shaped grains in ZrO 2 doped glass ceramic samples has been verified. The proportion of [AlO 6 ] units is strongly correlated with NIR spectra, suggesting that the strategy for modulation the NIR luminescence through oriented growth can be generalized as a universal method for manipulation of the optical properties for transition metal ion activated crystals with the mullite type structure. [ABSTRACT FROM AUTHOR]