ELECTRON-SPECTROSCOPY OF LIQUID PD-SI AND PD-BI ALLOYS

Liquid alloys containing transition metals have been investigated by means of photoelectron spectroscopy (UPS and XPS). Bismuth based dilute Ni and Pd alloys reveal valence band (VB) spectra with markedly shifted 3d and 4d electron states with respect to the pure alloy constituents. In PdSi the d band exhibits a temperature dependent shift towards lower binding energies with increasing temperature. A similar temperature dependence of the d band positions and core level binding energies has been found in liquid AuSn alloys. The VB spectra of liquid PdSi are compared with corresponding measurements on glassy PdSi. The great similarity of the VB spectra of the liquid and amorphous phases indicates a close resemblance of the atomic structure. However, due to the temperature induced band shift the Pd d state density at the Fermi level is markedly increased with respect to the amorphous phase. The surface segregation effects observed both in the liquid and solid phase are discussed. © 1990.