Photoluminescence properties of green and red luminescence from natural and heat?treated sodalite

摘要

The sodalite sample used in this investigation did not exhibit the characteristic orange-yellow luminescence due to the S_2~? center, because there was no trace of sulfur impurity. The heat-treated samples exhibited green and red luminescence with maximum intensity at 496 and 687 nm, respectively, under 264 nm excitation at room temperature. Their luminescence intensities were extensively dependent on the treatment temperature. The green luminescence efficiency of the sample heat-treated at 900 °C was 6.5 times higher than that of unheated natural sodalite. At 8.5 K, the green luminescence showed a vibronic structure. After heating at 1,300 °C, the crystal structure of sodalite was transformed to NaAlSiO_4 (carnegieite), and the intense red luminescence was exhibited in the NaAlSiO_4 sample. The peak wavelength of the red luminescence shifted from 687 nm at 300 K to 726 nm at 8.5 K. The luminescence lifetimes of the green and red luminescence at room temperature were 2.1 and 5.1 ms, respectively. It was proposed that the origin of the green luminescence is Mn~(2+) replacing Na~+, and that of the red luminescence is Fe~(3+) replacing Al~(3+) in sodalite or NaAl- SiO_4 (carnegieite).