Metallic nanoparticle formation in ion-implanted silica after thermal annealing in reducing or oxidizing atmospheres

Abstract High-purity silica samples with OH content less than 1 ppm, were implanted with 2 MeV Cu + , Ag + and Au 2+ ions at fluences of 0.7, 3 and 6×10 16 ions/cm 2 , and annealed in either reducing (70%N 2 +30%H 2 ) or oxidizing (air) atmosphere at 300, 600, 900 and 1100 °C for 1 h. For the three implanted species, after annealing at 900 °C in the reducing atmosphere, the absorption spectra present a broad band at 250 nm (4.9 eV), even for samples in which there are no nanoparticles formed. The nanoparticle formation in both atmospheres is quite different for the three implanted ions.