Structural modifications induced in silicate glass by field-aided solid-state diffusion of gold and chromium ions

• Field-aided diffusion of Au and Cr ions in sodalime silicate glass was investigated.
• The size of the nanoparticles increased with increasing treatment temperature.
• The exchange of larger alkali ions with smaller Au and Cr ions modified glass structure.
• Structurally modification of the glass surface was observed up to a depth of 1 μm.
• The surface of the ion-diffused glass was smooth enough for optical applications.

The main objective of this study was to investigate the effect of dopants on the optical properties of sodalime silicate glasses. Consequently, gold and chromium ions were incorporated in the glass matrix via field-aided diffusion for the enhancement of optical properties. The subsequent structural modifications were investigated using secondary ion mass spectrometry, infrared spectroscopy, optical absorption and scanning electron microscopy. Diffusion of Au and Cr ions was carried out at temperatures ranging from 150 °C to 450 °C in an external electric field of strength 100 V/mm to 500 V/mm for 30 to 90 min durations. Diffusion modified the glass structure in the superficial region up to a depth of 1 μm. Analysis of the secondary ion mass spectra revealed uniform diffusion of the dopants and the diameter of the nanoparticles derived from their absorption spectra increased with increasing temperature. The additional bands observed for the doped samples at 1070 cm− 1, 1112 cm− 1 and 1219 cm− 1 may be due to asymmetric stretching of Si–O–Si induced by Au and Cr diffusion. These structural modifications may be associated with the replacement of the larger host alkali ions (rNa + = 0.99 Å and rCa + = 1.0 Å) with the smaller dopant ions (rAu3 + = 0.85 Å and rCr3 + = 0.615 Å or rCr6 + = 0.26 Å). In spite of these structural modifications, the surface of the ion-diffused glass was smooth enough for possible optical applications.