S. Wannaparhun et al /Applied Surface Science 185(2002)183-196 A1(2s) d B E.ev) Fig. 2. XPS survey spectrum of the as-received alumina matrix: (a)first satellite of Al(2s); (b)Si(2p)region; (c)second satellite of Al(2s) (d) first satellite of Alo decrease in Si/Al ratio will shift all the peaks to lower indicates the presence of Al2O3(73.7eV [51]. The Be due to ionicity/covalency (IC) effect [50]. This peak at 74.6 eV with 6.3% area was aluminosilicate particular feature was also observed in this study. Thus (74.6eV [51, 52]). The latter is consistent with the the presence of silicon was evident in the as-received Si/Al ratio(0.03)mentioned previously for the as- alumina matrix received alumina with silicon as a foreign phase L.. Detailed ch 3.1.1.1. XPS Al(2p). Al(2p)spectra for mullite and alumina are illustrated in Fig 3. As shown in Fig. 4a. the deconvoluted Al(2p) spectrum was composed of two peaks located at 73.6 and 74.6eV (Table 1), respectively. The peak at 73.6eV with 93. 7%area Mullite 70 80 BE.(ev) Fig 4. Deconvoluted Al(2p) XPS spectrum of the as-received:(a) Fig. 3. XPS Al(2p) spectrum of the as-received: (a) alumina alumina matrix;(b)mullite(1: aluminum oxide; 2: aluminosili- matrix;(b)mullite.decrease in Si/Al ratio will shift all the peaks to lower BE due to ionicity/covalency (IC) effect [50]. This particular feature was also observed in this study. Thus the presence of silicon was evident in the as-received alumina matrix. 3.1.1. Detailed chemistry 3.1.1.1. XPS Al(2p). Al(2p) spectra for mullite and alumina are illustrated in Fig. 3. As shown in Fig. 4a, the deconvoluted Al(2p) spectrum was composed of two peaks located at 73.6 and 74.6 eV (Table 1), respectively. The peak at 73.6 eV with 93.7% area indicates the presence of Al2O3 (73.7 eV [51]). The peak at 74.6 eV with 6.3% area was aluminosilicate (74.6 eV [51,52]). The latter is consistent with the Si/Al ratio (0.03) mentioned previously for the as￾received alumina with silicon as a foreign phase. Fig. 2. XPS survey spectrum of the as-received alumina matrix: (a) first satellite of Al(2s); (b) Si(2p3 ) region; (c) second satellite of Al(2s); (d) first satellite of Al(2p). Fig. 3. XPS Al(2p) spectrum of the as-received: (a) alumina matrix; (b) mullite. Fig. 4. Deconvoluted Al(2p) XPS spectrum of the as-received: (a) alumina matrix; (b) mullite (1: aluminum oxide; 2: aluminosili￾cate). 186 S. Wannaparhun et al. / Applied Surface Science 185 (2002) 183–196