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 x Bi 2 O 3 – y Al 2 O 3 –(100 − x – y )NaPO 3 ( 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). 31 P MAS NMR spectroscopy demonstrates that the addition of Bi 2 O 3 and Al 2 O 3 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 31 P single pulse, 31 P{ 27 Al} rotational echo adiabatic passage double resonance, 31 P{ 27 Al} J-coupling-based heteronuclear multiple-quantum coherence, and 1D refocused INADEQUATE experiments. The results of 23 Na{ 31 P}, 31 P{ 23 Na}, 27 Al{ 31 P} rotational echo double resonance, and XPS consistently confirm that Na + , Al 3+ , and Bi 3+ ions are all bound by phosphorus tetrahedron [PO 4 ] 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 Bi 2 O 3 –Al 2 O 3 –NaPO 3 glasses.