Network of Bi2O3–Al2O3–NaPO3 glasses studied by solid‐state nuclear magnetic resonance spectroscopy

Abstract

AbstractA detailed structural investigation of a series of phosphate laser glasses with composition xBi2O3–yAl2O3–(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). 31P MAS NMR spectroscopy demonstrates that the addition of Bi2O3 and Al2O3 leads to the depolymerization of the phosphorus chain in the process of Q2 → Q1 → Q0. The various phosphorus species (Qn, n = 0, 1, 2) are identified by 31P single pulse, 31P{27Al} rotational echo adiabatic passage double resonance, 31P{27Al} J‐coupling‐based heteronuclear multiple‐quantum coherence, and 1D refocused INADEQUATE experiments. The results of 23Na{31P}, 31P{23Na}, 27Al{31P} 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.