The decomposition of PdSi by adding a small amount of Ag

Abstract

The decomposition of the intermetallic compound PdSi by adding a small amount of Ag has been investigated by thermal analysis, metallographic measurement, and x-ray photoemission spectroscopy (XPS). Within the range of Ag concentration from 0 to 6 at.%, PdSi is decomposed in linear proportion to the concentration of Ag into Si and the ternary compound Pd2Si(Ag), which has the ratio of 16 PdSi molecules per single Ag atom. The PdSi is fully decomposed at Ag 10 at.%. In the ternary alloy included in the Pd–Si–Ag alloy involving Ag below 12 at. %, the atomic ratio of Si to metal atoms, which are Pd plus Ag, is nearly the same as the ratio in Pd-rich Pd2Si. Metallographic and XPS measurements indicate that the Ag atom included in the PdSi behaves as an electron donor with a large radius of the wave function; the Ag electron transfers to the anti-bonding state of PdSi and acts to decompose the compound. The Ag atoms seem to occupy the sites of Pd atoms in Pd2Si(Ag) which has been decomposed from PdSi.