... 40 and 90 nm (see Fig 2b and c) SN, SN-650 and SN-850 powders showed speci®c surface areas of 31, 31 and 17 m2 gÀ1, respectively W 1-6 50 and W 5-6 50 pellets showed speci®c surface area of 25 and ... representing the line of absorbance zero in Fig 5a, a broad, weak, and negative 93 Fig Time resolved effects of mbar of NO2 at RT on FT-IR spectra of (a) SN-650, (b) W 1-6 50 and (c) W 5-6 50 pellets Spectra ... Effects of mbar of the NO2/O2 mixture at 1508C on FT-IR spectra of SN-650 and W 5-6 50 pellets (curves and 2, respectively) The dotted line represents the zero of absorbance 3.3 Electrical characterization...