Structural Studies of Bi2O3–NaPO3 Glasses by Solid State Nuclear Magnetic Resonance and X-ray Photoelectron Spectroscopy

Glasses in the system xBi2O3–(100 – x)NaPO3 were prepared using transitional melting–quenching and characterized using solid state nuclear magnetic resonance (SSNMR), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FT-IR). The addition of Bi2O3 results in the depolymerization of the phosphorus chain and the formation of Q(n) (n = 0, 1, 2) phosphorus species, where n represents the number of P–O–P bonds that can be quantified using 31P magic angle spinning (MAS) NMR and constant-time double-quantum based dipolar recoupling effects nuclear alignment reduction (CT-DQ-DRENAR). The 23Na{31P}, 31P{23Na}, and XPS results consistently prove that both Na+ and Bi3+ ions are bounded by phosphorus tetrahedron [PO4]3–. Unlike other trivalent ions such as Ga3+ and Al3+, which connect with the phosphorus tetrahedron by corner-sharing, Bi3+ ions were first proved to share edge with the phosphorus tetrahedron by the analysis of 31P spectra, taking the charge balance and bond valence consideration into account. Such a difference in connectivity results in significant structural differences.