Vaporization behaviour and some thermodynamic properties of the Pd-In, Pd-Pb, Pd-Sn systems

In this study, the vaporization behaviour of solid Pd-rich phases in the Pd -Pb, Pd-In and Pd-Sn systems was investigated by Knudsen-effusion-cell coup led with mass-spectrometry. The Pb, Pd, In vapor pressures [no Sn(g) has be en detected in the vapor of Pd-Sn system] were evaluated in the temperature s range 1190-1563 K from the ion intensities measured over two-phases regio ns. Thermodynamic quantities were derived from vapor pressure data. In part icular, for the Pd-Sn binary, the intermediate phase Pd7Sn2, the existence of which has been recently proposed, has been studied here for the first ti me. Furthermore, preliminary thermochemical data are presented for the diat omic intermetallic molecules PdSn and PdPb, which have been for the first t ime identified in the vapors in equilibrium over liquid solutions of approp riate composition at higher temperatures (1935-2025 K). (C) 2000 Elsevier S cience Ltd. All rights reserved.