Luminescence properties of reduced SrO-Al2O3-GeO2 glasses

We report on the luminescence properties of reduced SrO-Al2O3-GeO2 glasses. Metal Al instead of corresponding oxide (Al2O3) is added into SrO-Al2O3-GeO2 glasses in order to control the oxygen-deficient defects. The obtained transparent glass samples, in which Ge2+ defects are stable, emit bright blue, white, and red light when excited by 300, 335 and 370 nm ultraviolet light, respectively. Quantities of the defects can be controlled by adjusting the amount of metal Al, resulting in tunable luminescence from blue to white and to red. The origins of different luminescence centers are discussed and the color coordinates of the photoluminescence spectra are also calculated.