Based on the molar ratio of oxygen and phosphorus (O/P ⩾ 3.5), only Q1 and Q0 units exist in the studied barium iron phosphate glass. However, certain amount of Q0 and Q2groups also exists, which may result from the disproportionation reactions (Reaction (1)) in glass melts [48] and [49].
equation(1)
2Q1↔Q2+Q0
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As shown in Fig. 5, the absorption bands of the majority peaks at high wavenumber (1300–800 cm−1) are large. There are shoulders in the antisymmetric band. In order to verify the relative contribution of Q0, Q1 and Q2 units in the spectral range 1300–800 cm−1, a deconvolution of the experimental spectra is necessary. Therefore, the broad band is deconvoluted using Gaussian peak fit method [11], [27] and [50]. The deconvolution data (band center and relative area under bands) of the studied glasses are shown in Fig. 6 and listed in Table 2.