Mass spectrometric investigation of the dissociation energy of the molecule AlAu and estimated bond energies of some diatomic intermetallic compounds with gold

摘要

Highhyphen;temperature Knudsenhyphen;cell mass spectrometry has been used to measure the gaseous equilibria over an aluminumhyphen;gold or aluminumhyphen;silverhyphen;gold alloy in a tantalum cell. The enthalpies for the reactions (1)AlAulpar;grpar; equals; Allpar;grpar;plus;Aulpar;grpar;, and (2)AlAulpar;grpar;plus;Aulpar;grpar;equals;Au2lpar;grpar; plus;Allpar;grpar;were measured. The following dissociation energyDdeg;0, heat of sublimationDgr; Hdeg;s,298, and heat of formationDgr; Hdeg;f,298were derived from these reaction enthalpies for gaseousAlAu: 77.0 plusmn; 1.5,thinsp;98.4 plusmn; 2.5,thinsp;andthinsp;88.9 plusmn; 2.0thinsp;kcal moleminus;1, respectively. The dissociation energy of AlAu(g) has been interpreted in terms of the Pauling model of a polar bond. This model has been used to calculate dissociation energies of selected intermetallic compounds between transition metals, Group III metals, and Group IV metals with gold, which are compared with available literature data.