Local structure of zinc ultraphosphate glasses containing large amount of hydroxyl groups: 31P and 1H solid state nuclear magnetic resonance investigation

• Published in: Journal of non-crystalline solids Vol. 224; no. 2; pp. 163 - 172
• Main Authors: Mercier, C., Montagne, L., Sfihi, H., Palavit, G., Boivin, J.C., Legrand, A.P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.1998; Elsevier
• Subjects: Condensed matter: structure, mechanical and thermal properties; Disordered solids; Exact sciences and technology; Glasses; Physics; Structure of solids and liquids; crystallography; Hydrogen 1; Local structure; Inorganic compounds; Transition element compounds; Phosphorus 31; Zinc Hydroxides phosphates; NMR spectra; Phosphate glass; Experimental study; Polyphosphates; Quaternary compounds; Amorphous state structure
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/S0022-3093(97)00473-0

Zinc ultraphosphate glasses containing variable amounts of hydroxyl groups were prepared by melting phosphoric acid and zinc oxide at 900°C for different times. The 1H- 31P cross polarization (CP) combined with magic angle spinning (MAS) nuclear magnetic resonance (NMR) at variable contact time show clearly the presence of Q 2 sites including those bonded to H +, Q 2(H), and those bonded to Zn 2+, Q 2(Zn), and Q 3 sites. Moreover, the detailed examination of the line widths reveals that the Q n sites are distributed in the glass matrix, particularly the Q 2(H) sites. A quantification of the measurements indicates an evolution of the relative fractions of the sites versus the melting time. 1H MAS NMR reveals the existence of at least three kind of protons characterized by different isotropic chemical shifts: 17 ± 0.2, 13 ± 0.2 and 8.6 ± 0.2 ppm. These protons are identified as those involved, respectively, in Q 2(H)…Q 2(Zn) groups, in Q 2(H)…Q 2(H) groups and those of water molecules adsorbed on the glass surface. The measurements of spin lattice and spin-spin relaxation times indicate that the water molecules are strongly adsorbed and that the protons involved in Q 2(H)…Q 2(Zn) and in Q 2(H)…Q 2(H)…Q 2(H) are homogeneously distributed in the glass matrix, in good agreement with the analysis of 31P NMR data.