2-DIMENSIONAL SMALL-ANGLE X-RAY-SCATTERING INVESTIGATION OF STRETCHEDBOROSILICATE GLASSES

A two-dimensional fit of a suitable model for interpreting small-angle X-ray scattering (SAXS) has been shown to be a valuable tool in obtai ning quantitative microstructural information. The model is based on t he hypothesis that dilute ellipsoidal particles are arranged parallel to each other. The method has been applied to two glasses containing o riented particles. The investigated materials are both alkali aluminob orosilicate glasses, thermally treated and redrawn at a temperature ab ove their softening point. The Ag(Cl,Br) crystalline droplets, formed during the preliminary thermal treatment, assume, after drawing, a cig ar-like shape, oriented in the stretching direction, and give the mate rial birefringence properties. The volumetric particle distribution ha s an average of 22 x 70 nm and is skewed up to length values of about 1200 nm. The composition of the solid solution, determined by X-ray di ffraction (XRD), is Ag(Cl-0.35, Br-0.65) When the Ag(Cl,Br) particles on the surface are chemically reduced to Ag, a material with polarizin g properties is obtained (Polarcor(TM)). For this sample, two distribu tions of particles have been found: one with an average of Is x 230 nm and skewed up to 600 nm, and one, very sharp, of much shorter particl es (14 x 30 nm).