Network of Bi2O3–Al2O3–NaPO3 Glasses Studied by Solid‐state Nuclear Magnetic Resonance Spectroscopy

A detailed structural investigation of a series of phosphate laser glasses with composition xBi(2)O(3)-yAl(2)O(3)-(100 - x-y)NaPO3 (x = 0, 10; y = 0, 5, 10, 15, 20) has been conducted using solid-state nuclear magnetic resonance (NMR) techniques and X-ray photoelectron spectroscopy (XPS). P-31 MAS NMR spectroscopy demonstrates that the addition of Bi2O3 and Al2O3 leads to the depolymerization of the phosphorus chain in the process of Q(2) -> Q(1) -> Q(0). The various phosphorus species (Q(n), n = 0, 1, 2) are identified by P-31 single pulse, P-31{Al-27} rotational echo adiabatic passage double resonance, P-31{Al-27} J-coupling-based heteronuclear multiple-quantum coherence, and 1D refocused INADEQUATE experiments. The results of Na-23{P-31}, P-31{Na-23}, Al-27{P-31} rotational echo double resonance, and XPS consistently confirm that Na+, Al3+, and Bi3+ ions are all bound by phosphorus tetrahedron [PO4](3-). No bond is formed between these glass modifiers. Based on the complementary evidence from previous experiments, comprehensive local structure models are developed for these Bi2O3-Al2O3-NaPO3 glasses.