Size effect on surface structural relaxation kinetics of silica glass sample

It is known that surface structural relaxation takes place more rapidly than bulk structural relaxation, especially in the presence of water vapor. The surface structural relaxation kinetics of the silica glass fiber and plates was compared at 950 C and the surface structural relaxation kinetics of silica glass fiber was found to be faster than that of the silica glass plate, even though the composition and initial fictive temperatures of the samples were the same. The observed difference of the surface structural relaxation kinetics between silica glass fiber and silica glass plate can be accounted for using a diffusion equation with time-dependent surface concentration. The analysis indicates that there is a general size effect on the surface structural relaxation kinetics, with smaller sized samples exhibiting faster relaxation kinetics. 2006 Elsevier B.V. All rights reserved. PACS: 61.43.Fs; 64.70.Pf; 65.80.+n; 78.30. j