Structural Roles of Boron and Silicon in the CaO-SiO 2 -B 2 O 3 Glasses Using FTIR, Raman, and NMR Spectroscopy
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silicate-based glasses and melts are important materials because of their wide applications in glass industry.[1–4] and metallurgical industry.[5–9] The macroscopic properties of these glasses and melts are primarily YONGQI SUN, Ph.D Candidate, is with the Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, P.R. China. ZUOTAI ZHANG, Professor, is with the Department of Energy and Resources Engineering, College of Engineering, Peking University and also with the Beijing Key Laboratory for Solid Waste Utilization and Management, College of Engineering, Peking University, Beijing 100871, P.R. China. Contact e-mail: [email protected] Manuscript submitted February 4, 2015. Article published online May 27, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
determined by the microscopic structure; thus it is of crucial importance to acquire the structural environments of boron (B) and silicon (Si) including the role and coordination conditions. Meanwhile, numerous studies[5–7, 10–17] explored the viscous flow behavior and analyzed the variation trend of the viscosities of B2O3-bearing melts. The foregoing investigations on the structures and viscosities of borosilicate glasses and melts could be categorized into three types. First, many researchers[6,10–16] measured the viscosity of borosilicate melts and discovered that the viscosity remarkably or slightly decreased with increasing B2O3 content depending on the melt components, while the discussion on the varying viscosity was focused on the overall nature of B2O3 with a low-melting point. Second, recently several studies[5,7,17] investigated the viscosities of boron-bearing melts from the prospect of qualitative analysis of the melt structures using Fourier transformation infrared (FTIR) and Raman spectra. Third, because of the crucial importance of borosilicate glasses, many studies have explored the structures of borosilicate glasses[1–4] and substantial knowledge has been obtained. As for the Si-related structures, there were five structural units of SiO4 tetrahedral,[18–21] which could be denoted as Qi(Si) (i = 0, 1, 2, 3, 4), where i represents the number of bridging oxygens (BO). The mole fraction of these structural units could be derived based on the deconvolutions of the Raman or magic angular spinning nuclear magnetic resonance (MAS-NMR) curves. Parkinson et al.[22] found that the fraction of Q3(Si) decreased with more alkali in the borosilicate glasses using Raman and 29Si MAS-NMR spectra. As for the B-related groups, the main structural units were BO3 trigonal and BO4 tetrahedron in the networks, the content of which could be deduced according to the Raman spectra or the 11B MAS-NMR spectra. Du et al.[3,4] and Zhu et al.[23] separately investigated the nature of Na2O-SiO2-B2O3 and Bi2O3-SiO2-B2O3 glasses using 11B MAS-NMR, and found that the basic B-related structures were composed of 3 to 5 structural units. However, there was limited quantitative analysis of the relationship between the viscous flow beh
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