Local structure of xK2SO4 · (95−x)ZnSO4 · 5CoSO4 glasses and crystallization of 60K2SO4 · 30ZnSO4 · 5CoSO4 · 5Fe2(SO4)3 glass

Abstract The local structure of a series of sulfate glasses, x K 2 SO 4 · (95− x )ZnSO 4 · 5CoSO 4 , was investigated by means of Fourier transform infrared (FTIR) spectroscopy. The peak intensity of IR-inactive ν 1 and ν 2 modes decreased with increasing K 2 SO 4 content, reflecting the increasing symmetry of the distorted SO 4 2− tetrahedra. A gradual decrease in the glass transition temperature was observed as a result of the increased symmetry of SO 4 2− tetrahedra. 57 Fe Mossbauer spectra of heat-treated 60K 2 SO 4 · 30ZnSO 4 · 5CoSO 4 · 5Fe 2 (SO 4 ) 3 showed an intense singlet due to cubic Fe 3+ (octahedra) occupying lattice sites of crystalline K 3 Fe(SO 4 ) 3 phase, together with a weak doublet due to ionic Fe 3+ remaining in the original glassy phase. The FTIR spectra of the heat-treated treated samples proved that the symmetry of the distorted SO 4 2− tetrahedra was lowered as a result of the crystallization.