Ambience-induced alternating change of optical absorption for the porous silica host Loaded with silver nanometer particles

Reversible change of optical absorption with alternating exposure to ambient environment with high relative humidity and thermal annealing at 573 K to 973 K is reported for the porous silica host dispersed with silver nanometer particles within its pores. A phase, silver silicate was found at the interface between pore walls and silver particles within pores. The formation of the interface phase is responsible for the ever-increasing absorption peak at around 410 nm and back ground absorption in the whole measured region. From optical absorption measurements, the formation amount of the interface phase was found to be subject to a power function of exposure time to a given ambience. This interface phase can be eliminated by subsequent annealing at 573 K to 973 K. The alternating change of optical absorption is explained by formation and decomposition of the interface phase induced by a given ambient condition.