3
44
K.-W. Wang et al. / Journal of Alloys and Compounds 426 (2006) 341–344
influence of surface modification is reduced when the surfactants
◦
are gradually desorbed or decomposed at 350 C.
Acknowledgements
We acknowledge the support of this work by the Ministry
of Education of Taiwan under Contract No. A-91-E-FA04-1-4
and National Science Council of Taiwan under Contract No.
NSC-91-2120-E-007-003.
References
[
[
[
1] M. Efentakis, H. Al-Hmoud, G. Buckton, Z. Rajan, Int. J. Pharm. 70 (1991)
53.
2] Z. Hu, L. Wei, J. Dong, Y. Wang, S. Chen, S. Peng, Microporous Meso-
porous Mater. 28 (1999) 49.
1
3] A.B. Bourlinos, A. Bakandritsos, V. Georgakilas, D. Petridis, Chem. Mater.
14 (2002) 3226.
[
[
[
4] X. Liu, Y. Guan, Z. Ma, H. Liu, Langmuir 20 (2004) 10278.
5] J.H. Chen, E. Ruckenstein, J. Colloid Interface Sci. 142 (1991) 544.
6] W.D. Kingery, H.K. Bowen, D.R. Uhlmann, Introduction to Ceramics, sec-
ond ed., John Wiley & Sons, 1991, p. 181.
[
7] G. Mattei, G. Battaglin, V. Bello, E. Cattaruzza, C.D. Julian, G.D. Marchi,
C. Maurizio, P. Mazzoldi, M. Parolin, C. Sada, Nucl. Instrum. Meth. B 218
(
2004) 433.
[8] G. Mattei, G.D. Marchi, C. Maurizio, P. Mazzoldi, C. Sada, V. Bello, Phys.
Rev. Lett. 90 (2003) 085502.
Fig. 4. XANES for the L3 edge of Ag in three Pd70Ag30 samples heated to
[9] G. Battaglin, E. Cattaruzza, G.D. Marchi, F. Gonella, G. Mattei, C. Maur-
izio, P. Mazzoldi, M. Parolin, C. Sada, I. Calliari, Nucl. Instrum. Meth. B
◦
2
50 C in air. The L3 edges for Pd and Ag are at 3173 and 3351eV, respectively.
191 (2002) 392.
[
10] G. Battaglin, M. Catalano, E. Cattaruzza, F. D’Acapito, C.D.J. Fernandez,
G.D. Marchi, F. Gonella, G. Mattei, C. Maurizio, P. Mazzoldi, A. Miotello,
C. Sada, Nucl. Instrum. Meth. B 178 (2001) 176.
4
. Conclusion
[
[
[
11] A. Vazquez, F. Pedraza, Appl. Surf. Sci. 99 (1996) 213.
12] K.W. Wang, S.R. Chung, T.P. Perng, J. Alloys Compd., in press.
13] C.Y. Huang, H.J. Chiang, J.C. Huang, S.R. Sheen, Nanostruct. Mater. 10
(1998) 1393.
In summary, this work demonstrates that the competition of
surface segregation of Ag and oxidation of Pd in Pd70Ag30 alloy
◦
nanoparticlescanbeaffectedbysurfacemodification. At250 C,
[
[
[
14] H.C. Chu, S.R. Sheen, C.T. Yeh, T.P. Perng, J. Alloys Compd. 322 (2001)
de-alloying of Ag occurs in unmodified Pd70Ag30 because of
preferential oxidation of Pd. This process is moderately sup-
pressed by modification with SA. For Pd70Ag30-p nanoparticles,
oxidation of Pd is much more suppressed. Ag is enriched on the
nanoparticle surface, but no free Ag is formed on the pellet. The
198.
15] K.W. Wang, S.R. Chung, L.Y. Jang, J.F. Lee, T.P. Perng, J. Alloys Compd.,
in press.
16] G. Cheng, T. Guo, J. Phys. Chem. B 106 (2002) 5833.
[17] H.Y. Lee, T.B. Wu, J.F. Lee, J. Appl. Phys. 80 (1996) 2175.