Strong white photoluminescence from annealed zeolites

The optical properties of zeolites annealed at various temperatures are investigated for the first time. The annealed zeolites exhibit strong white photoluminescence (PL) under ultraviolet light excitation. With increasing annealing temperature, the emission intensity of annealed zeolites first increases and then decreases. At the same time, the PL peak red-shifts from 495 nm to 530 nm, and then returns to 500 nm. The strongest emission appears when the annealing temperature is 500 degrees C. The quantum yield of the sample is measured to be similar to 10%. The PL lifetime monotonously increases from 223 mu s to 251 mu s with increasing annealing temperature. The origin of white PL is ascribed to oxygen vacancies formed during the annealing process. (C) 2013 Elsevier B.V. All rights reserved.