JOINT EFFECT OF GAMMA-IRRADIATION AND TIO2 NUCLEATION ON THE CRYSTALLIZATION OF (LI-2, R)O ALUMINOSILICATE GLASS WITH AND WITHOUT IRON-OXIDE ADDITION

The effect of gamma radiation and adding iron oxide on the nucleation and crystallization of a complex multicomponent glass based on spodume ne, willemite, diopside and nucleated by titania has been elucidated u sing DTA, X-ray diffraction and polarizing microscopic techniques. Dif ferent crystalline-phase assemblages, including beta-eucryptite ss, be ta- and chi-Zn2SiO4, augite, and beta-spodumene were found to coexist in the crystallized glass depending upon the temperature of thermal tr eatments as well as the irradiation process. The conversion of beta-Zn 2SiO4 and/or direct formation of chi-phase (willemite) was greatly enh anced by irradiation. Intense uniform bulk crystallization was enhance d by irradiating the glasses with gamma rays before thermal treatments . This catalytic effect of gamma irradiation on the crystallization wa s explained on the basis of stimulating the nucleation process by incr easing nucleating sites because of the relatively easier rearrangement of the irradiated glass structure. The addition of iron oxide to the glass seems to obscure the effect of gamma radiation, yet it facilitat es the formation of heterogeneous nucleation centres in the glass.