Influence of Thermal Treatments on the Photoluminescence Characteristics of Nanometer-Sized Amorphous Silica Particles

Abstract

We have studied the photoluminescence (PL) characteristics of nanometer-sized amorphous silica particles after appropriate annealing in air and in vacuum. A broad visible PL band peaking at ∼450 nm, which is characterized by a nonexponential decay in the order of nanoseconds, has been found to develop when the samples are heat-treated in air. On the other hand, the vacuum-heated samples do not show such an increase in PL in the visible region but instead show a development of PL in the near-ultraviolet region. The different PL characteristics observed between the air- and vacuum-heated samples are discussed in terms of the different dehydroxylation reactions in air and in vacuum. Possible models of the respective emission centers are presented on the basis of the density functional theory calculations.