UNIAXIAL-STRESS RELAXATION MEASUREMENT IN FLUOROINDATE GLASSES

Glasses of composition 40InF(3)-20SrF(2)-16BaF(2)-2OZnF(2)-2GdF(3)-2Na F (mol%) have been prepared under controlled atmosphere. The time resp onse of the stresses under the application of a constant strain was de termined by microellipsometer technique, performed in ambient atmosphe re at T < T-g= 294 degrees C. The glasses show a Newtonian behavior at small stress level. During the relaxation process, very small grooves perpendicular to the applied strain appeared on the glass surface and affected its behavior after a time. The formation of these grooves is associated with the ambient atmosphere. Measurements in dry atmospher e showed that humidity was an important parameter in tho relaxation pr ocess.