Effect of Silica Surface Area on Molecular Structures of Lead in Thermally Treated Mixtures of Lead Acetate and Silica Oxide

Journal Article · Fri Feb 02 00:00:00 EST 2007 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2644622· OSTI ID:21054710

Yuling, Wei; Cheng, K -W; Cheng, Nicky ^[1]; Wang, H Paul ^[2]

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1. Department of Environmental Science and Engineering, Tunghai University, Taichung City, 407 Taiwan (China)
2. Department of Environmental Engineering, National Cheng-Kung University, Tainan City, 700 Taiwan (China)

The extent of lead dispersion can affect lead molecular environment in lead silicate. Mixtures of lead acetate and silica oxide were heated at 500 and 1100 deg. C for two hours. Two silica oxides (a quartz, syn and an amorphous SiO2) of different surface areas were used in this study. The final products were investigated with X-ray absorption spectroscopy, X-ray diffraction, BET surface meter, and scanning electron microscopy. The XRD results observe the existence of PbSiO3, Pb(0), and PbO (litharge, syn) only in the mixture of lead acetate and quartz heated at 1100 deg. C, as well as SiO2 (cristobalite, syn). The mixture of lead acetate and the amorphous SiO2 heated at 1100 deg. C basically remains as amorphous although its XRD patterns do show some low-intensity peaks of SiO2 (cristobalite, syn). Both BET and SEM results indicate that sintering occurs at 1100 deg. C. Results from the fitting of Fourier transformed Pb LIII-edge EXAFS spectra from the heated mixtures shows that both first-shell (Pb-O) interatomic distance and coordination number depend on the type of starting materials and the thermal treatment temperature. Pb first-shell coordination number decreases with increasing temperature for both low-surface area and high-surface area mixtures. The high-surface area mixture after heating at 500 deg. C have greater first-shell coordination number than the corresponding low-surface area sample. However, after thermal treatment at 1100 deg. C, both mixtures have similar first-shell coordination number. The interatomic distance for the first shell for all thermally treated mixtures is 2.18-2.28 A. The high-surface area mixture treated at 1100 deg. C has the shortest first-shell interatomic distance (2.18 A)

• OSTI ID: 21054710
• Journal Information: AIP Conference Proceedings, Vol. 882, Issue 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644622; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
ACETATES
COORDINATION NUMBER
CRISTOBALITE
FINE STRUCTURE
GLASS
HEAT TREATMENTS
INTERATOMIC DISTANCES
LEAD
LEAD OXIDES
LEAD SILICATES
MOLECULAR STRUCTURE
QUARTZ
SCANNING ELECTRON MICROSCOPY
SILICA
SINTERING
SURFACE AREA
SURFACES
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY