Properties of mixed Na2O and K2O iron phosphate glasses

Glass formation and properties of iron phosphate glasses containing Na2O an d K2O have been investigated to determine the suitability of these glasses for disposing of certain types of nuclear wastes that contain one or more a lkali oxides. Two series of grasses of the general composition xK(2)O-(20 - x)Na2O-20Fe(2)O(3)-60P(2)O(5) and xK(2)O-(20 - x)Na2O-32Fe(2)O(3)-48P(2)O( 5), mol%, with x = 0, 5, 10, 15 and 20, were chosen for this investigation. The properties that have been measured include density, molar volume, chem ical durability, electrical resistivity, dielectric constant and LR spectra . No typical mixed alkali effect, namely, a minimum or maximum in the prope rties as a function of the ratio of two alkali ions, was observed for these glasses. The present results show that iron phosphate glasses can be suita ble for vitrifying nuclear wastes that contain amounts of one or more alkal i oxides less than or equal to 20 mol%. An Fe/P ratio of the compositions a t about 0.67 and the O/P ratio between 3.5 and 3.7 are desirable to obtain the maximum chemical durability of the wasteforms. (C) 2000 Elsevier Scienc e B.V. All rights reserved.