S. Wannaparhun et al /Applied Surface Science 185(2002)183-196 185 Nextel 720 fiber As-received Sol-gel process As-received trixs spectr umina matrix (100% matrix from sol-gel process) The as-received composite Fiber Spect (F)+(M) Composite (F)+(△M)+() F)+(M) Any during the processing? Fig. 1. Use of XPS to evaluate the interfacial chemistry of the composite material through spectral interpretation. Photoelectron from: F, fiber; As-received (5) 3.. Alumina o(Iscal=o(1s) XPS survey scan of the as-received alumina shown To compare the calculated and the as-received spectra, in Fig. 2 revealed two predominant peaks: (i)the main a graphical superimposition method was used. For Al(2p)coreline between 60 and 80 eV, and (ii) Al(2s) TEM analysis, the authors have followed a specimen and its satellites between 80 and 120 e V. The Be of preparation technique using a double layer model Al(2s) was around 119 eV and its first satellite was at (DLM) and focused ion beam(FlB)for an effective 9.4 eV downfield from the main Al(2s) peak. The surface/interface analysis of this insulating material second satellite of Al(2s) was located around 90- 49] 110 eV, close to Si(2p) lines. Similar satellites were observed for 1(2p) but with varying The surface Si/Al ratio calculated from XPS spectra 3. Results and discussion vas≈0.03 A surface Si/Al ratio is a good measurement to Primarily, both mullite and alumina were analyzed indicate the presence of silicon in the matrix, if any as reference materials to understand the fundamental Any change in Si/Al ratio will affect the position surface chemistry of this composite intensity of all the peaks in the XPS spectrum. ASið2p3 ÞCal ¼ Sið2p3 ÞAs-received (5) Oð1sÞCal ¼ Oð1sÞAs-received (6) To compare the calculated and the as-received spectra, a graphical superimposition method was used. For TEM analysis, the authors have followed a specimen preparation technique using a double layer model (DLM) and focused ion beam (FIB) for an effective surface/interface analysis of this insulating material [49]. 3. Results and discussion Primarily, both mullite and alumina were analyzed as reference materials to understand the fundamental surface chemistry of this composite. 3.1. Alumina XPS survey scan of the as-received alumina shown in Fig. 2 revealed two predominant peaks: (i) the main Al(2p) coreline between 60 and 80 eV, and (ii) Al(2s) and its satellites between 80 and 120 eV. The BE of Al(2s) was around 119 eV and its first satellite was at 9.4 eV downfield from the main Al(2s) peak. The second satellite of Al(2s) was located around 90– 110 eV, close to Si(2p3 ) lines. Similar satellites were also observed for Al(2p) but with varying intensity. The surface Si/Al ratio calculated from XPS spectra was 0.03. A surface Si/Al ratio is a good measurement to indicate the presence of silicon in the matrix, if any. Any change in Si/Al ratio will affect the position and intensity of all the peaks in the XPS spectrum. A Fig. 1. Use of XPS to evaluate the interfacial chemistry of the composite material through spectral interpretation. Photoelectron from: F, fiber; M, matrix; I, interface. S. Wannaparhun et al. / Applied Surface Science 185 (2002) 183–196 185