Structure and crystallization of (1 −x)(33.33Li2O-33.33Fe2O3-33.33P2O5) −xB2O3 glasses

Abstract The nominal composition of 33.33Li 2 O-33.33Fe 2 O 3 -33.33P 2 O 5 is difficult to generate bulky glass via the normal melt-quenching route. The experiments showed that the addition of B 2 O 3 benefited the formation of glass. Structure and crystallization behavior of (1 − x )(33.33Li 2 O-33.33Fe 2 O 3 -33.33P 2 O 5 ) − x B 2 O 3 (x = 5, 10, 15 and 20 mol%) glasses were investigated using Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction. The analysis results indicate the formation of [BO 4 ] tetrahedra within the glass network upon adding B 2 O 3 . Mainly due to the larger volume of [BO 4 ] compared with [PO 4 ], the density and the chemical durability of the glass decrease with the inclusion of B 2 O 3 . On the other hand, the integration and continuity of glass network increase due to the formation of B O P bonds. As a result, the glass transition temperature increases with B 2 O 3 . However, when the content of B 2 O 3 is more than 15 mol%, [BO 3 ] appears leading to large decreases in the density and the chemical stability of the glass. It is evidenced that more integrated network of glass samples containing 5 and 10 mol% of B 2 O 3 increases the possibility of phase separation in the glasses, contributing to the mixed surface and bulk crystallization mechanisms in these two samples. In contrast, the samples containing 15 and 20 mol% only show surface crystallization. All heat treated samples have main crystallization phases of Li 3 Fe 2 (PO 4 ) 3 and LiFePO 4 .