Equilibrium Pressures of Oxygen over Oxides of Lead at Various Temperatures

Abstract

PbO2 apparently requires four stages of decomposition to reach normalPbO . Based on thermogravimetric studies the intermediate products appear to be 5PbO2·4normalPbO , 4PbO2·5normalPbO , and Pb3O4 . Although the first three stages seem irreversible, they too come to a steady state in decomposition, but no recombination takes place. normalΔH° and normalΔS° values have been calculated for the four stages.

Standard molar Gibbs energy of formation of Pb5Bi8O17 and PbBi12O19 and phase diagram of the Pb–Bi–O system

“…[31]. As seen from the figure, the present data are in close agreement with the data reported by Reinders and Hamburger [27], Otto [28] and Kharif et al [30]. The figure also shows that the oxygen pressures reported by Le Chatelier [26] and by Abadir et al [29] and those calculated from the emf data reported by Mallika and Sreedharan [31] are in disagreement with the present data and are distinctly lower from the rest of the data.…”

“…Data on D f G m hPb 3 O 4 i have been reported in the literature based on similar measurements of the oxygen partial pressures by manometry [26][27][28][29][30] and also by the emf method [31], and these are listed along with the present data in Table 4. The experimentally measured oxygen pressures from all these references are compared in Fig.…”

Standard molar Gibbs free energy of formation of Pb5CrO8(s), Pb2CrO5(s), and PbCrO4(s)

“…The equilibrium oxygen pressures were measured between (777 and 865) K. The data obtained are given in table 3 and are also shown in figure 5. Figure also compares the current data with those of Reinders and Hamburger [19], Otto [20], Kharif et al [21] and Ganesan et al [22]. It is seen that the present data are in very good agreement with those reported in literature.…”

“…Variation of oxygen pressure in {PbO(s) + Pb 3 O 4 (s)} system with temperature. h Reinders and Hamburger[19], s Otto[20], r Kharif et al[21], 4Ganesan et al[22], } Present work.…”

Pb diffusion in rutile

“…Meyer et al (1998) have studied rutile implanted with Pb with RBS and channeling; their results indicate that Pb occupies Ti lattice sites. However, they contend that Pb is present in the +4 valence state; this is not likely to be the case in either our experiments or under most geologic conditions (e.g., Otto 1966;, where Pb is generally found in the divalent state.…”