ABSTRACTGlasses of the series (mol.%) 40 Na2O, (20-x)
Al2O3, x Fe2O3, 40
P2O5 were irradiated with 8 MeV electrons to doses
equivalent of 0.1, 0.5, and 1.0 MGy and characterized by FTIR spectroscopy and
ESR at room temperature. FTIR spectra of all the glasses consist of strong bands
due to O-P-O stretching modes in (PO4)3- and
(P2O7)4- units at 1000-1200
cm-1, P-O-P stretching modes at 900-950 cm-1
(νas) and 700-750 cm-1
(νs), and bending modes in the PO4 units. The
wavenumber range lower 800 cm-1 has some contribution due to
stretching modes in MO4 and MO6 (M = Al, Fe)
units. Moreover the bands at 3300-3700 cm-1 and 1550-1650
cm-1 due to stretching and bending modes in both absorbed and
structurally bound H2O molecules were present. As irradiation dose
increases the bands due to stretching and bending modes in water molecules and
M-O-H bonds become stronger and are split. No essential changes with increasing
dose were observed within the spectral range of stretching modes of the O-P-O
and P-O-P bonds. Irradiation yields phosphorus-oxygen hole centers -
PO42- (D5) and
PO42- (D6), and
PO32- ion-radicals (D2)
observable in ESR spectra of low-Fe glasses. At x>5 their responses are
overlapped with strong broad line due to Fe(III). On the whole, with the
increase in iron content the glass structural evolution decrease.
Iron Phosphate Glasses: An Alternative for Vitrifying Certain Nuclear Wastes
