Local Structure of amorphous (PbO){sub x}[(B{sub 2}O{sub 3}){sub 1-z}(Al{sub 2}O{sub 3}){sub z}]{sub y} (SiO{sub 2}){sub y} Dielectric Materials by Multinuclear Solid State NMR

Journal Article · Fri Sep 05 04:00:00 EDT 2003 · Chemistry of Materials

OSTI ID:15016013

Sawvel, A; Chinn, S; Bourcier, W; Maxwell, R

Structural speciation of glasses in the systems PbO-B{sub 2}O{sub 3}-SiO{sub 2}, PbO-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2}, and PbO-Al{sub 2}O{sub 3}-SiO{sub 2} were studied using solid-state {sup 29}Si, {sup 27}Al, {sup 11}B, and {sup 207}Pb nuclear magnetic resonance (NMR) and Raman spectroscopy. Application of these methods provided insight into the role of Al{sub 2}O{sub 3} incorporation in the lead-borosilicate glass networks. The general composition range studied was (PbO){sub x} [(B{sub 2}O{sub 3}){sub 1-z} (Al{sub 2}O{sub 3})z]{sub y}(SiO{sub 2}){sub y} where x = 0.35, 0.5, and 0.65, y = (1-x)/2 and z = 0.0, 0.5 and 1.0. Additional insight was obtained via {sup 27}Al 2D-3QMAS experiments. The {sup 207}Pb spin echo mapping spectra showed a transition from ionic (Pb{sup 2+}) to covalently bound lead species with increased PbO contents in the borosilicate glasses. The addition of aluminum to the glass network further enhanced the lead species transition resulting in a higher relative amount of covalent lead bonding in the high PbO content alumino-borosilicate glass. The number of BO{sub 4} units present in the {sup 11}B MAS NMR decreased with increasing PbO contents for both the borosilicate and the alumino-borosilicate glass systems, with the addition of aluminum further promoting the BO{sub 3} species. A deshielding of the {sup 11}B chemical shifts and the {sup 27}Al chemical shifts with increased lead contents (independent of changes in the quadrupolar coupling) was also observed for both glass systems and was attributed to increasingly homogeneous glass structure. The {sup 29}Si spectra of the borosilicate and alumino-borosilicate glasses showed a downfield shift with increased PbO concentrations representing incorporation of Pb into the silicate and aluminosilicate networks. The Raman spectra were characterized by increased intensities of Si-O-Pb peaks and decreased intensities of Q{sup 3} peaks with increased PbO contents and showed no evidence of BO{sub 3} or BO{sub 4} ring species. Both the NMR and the Raman data point toward systems where lead is increasingly incorporated into the B{sub 2}O{sub 3}-SiO{sub 2} and the B{sub 2}O{sub 3}-SiO{sub 2}-Al{sub 2}O{sub 3} networks at high PbO concentrations, with the addition of Al{sub 2}O{sub 3} enhancing the trend.

• Research Organization: Lawrence Livermore National Lab., Livermore, CA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 15016013
• Report Number(s): UCRL-JRNL-200058
• Journal Information: Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 6 Vol. 17; ISSN CMATEX; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
58 GEOSCIENCES
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM
BONDING
BOROSILICATE GLASS
CHEMICAL SHIFT
DIELECTRIC MATERIALS
GLASS
NUCLEAR MAGNETIC RESONANCE
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SILICATES
SPECTRA
SPIN ECHO