Mass Spectrometric Investigation of the Evaporation Properties of Lead Oxide

Abstract

Partial pressures of molecular species over solid PbO were measured in the temperature interval between 890 K and 1100 K using Knudsen-cell mass spectrometry. The assignment of ions is discussed in detail. Structural and vibrational parameters of the gas phase for (Pb n O n ) (n = 1,2,3,4) were calculated by the ab initio molecular orbital method at different approximation levels. Third law enthalpies of dissociation of Pb 2 O 2 and Pb 4 O 4 to monomeric PbO were obtained as (250.6 ± 6) kJ/mol and (835.0 ± 15) kJ/mol, respectively. The possibility of direct measurement of the dissociation pressure of PbO by a mass spectrometer is demonstrated.

A mass spectrometric and quantum chemical study of the vaporisation of lead monoxide in a flow of gaseous arsenic and antimony trioxides

“…[3][4][5] The enthalpies of oligomerisation for the lead oxides from the literature and our calculated values are compared in Table 11.…”

“…Several studies of the vaporisation of the pure oxides of PbO, [3][4][5] As 2 O 3 6,7 and Sb 2 O 3 8,9 using mass spectrometric methods have been reported by several authors. In the gas phase over solid lead monoxide at a temperature of approximately 1000 K, PbO, Pb 2 O 2 and Pb 4 O 4 were found to be the main compounds.…”

“…Very low concentrations of Pb 3 O 3 , Pb 5 O 5 and Pb 6 O 6 were also detected. [3][4][5] Mass spectrometric studies of the vaporisation of As 2 O 3 have shown that the gas phase of the As-O system is highly complex. 6 Besides gaseous As 4 O 6 and AsO species, which were previously known to exist in the gas phase, other stable species including As 4 O 5 , As 4 O 4 , As 4 O 3 , As 3 O 4 , As 2 O 3 and AsO 2 were detected in the gas phase.…”

“…The formation and thermodynamic stability of antimony monoxide SbO have been previously investigated by mass spectrometry. 10 The authors observed the formation of SbO species by the oxidation of atomic Sb at temperatures of approximately 1880 K. There are several gaseous ternary oxides such as SnPO 2 , SnPO 3 11 and GePO 3 , 12 which are related to the lead-arsenic and lead-antimony oxides, which have been detected using mass spectrometry. To the best of our knowledge, no other experimental and quantum chemical studies of gaseous ternary molecular oxides of groups 14 and 15 elements have been reported.…”

“…14 The equilibrium in the gas phase was investigated in the Knudsen cell over Sb 2 O 3 and PbO oxides too. [3][4][5]8,9,15 Using the partial pressures, we determined the equilibrium constants of the formation of the arsenic-lead and antimonylead ternary oxides, which will be given later in this paper.…”