Thermogravime tric measurements were performed on nonstoichlome tric Ce02-x in the temperature range 700' to 1500'C and from oxygen pressures -1 -26 of 10 to 10 atm. From this data the deviation from stolchlometry x = x(T,P ) was determined. The thermodynamic quantities AH and ASO 2 22 were calculated In the region 0.0003 f x < 0.3 and found to be Independent of temperature.In the composition region x < 0.001, the thermogravlmetric data Is assumed to be influenced by impurities.In the region 0.001

The electrical conductivity of sintered specimens of Cel+yO2 was measured over the temperature range 800~176and from I to 10 -21 atm of oxygen. Based on the agreement between these experimental data and theoretically derived relations obtained using the law of mass action, the nonstoichiometric defect structure of Ce~ +yO2 was interpreted in terms of a defect structure consisting of triply and quadruply ionized cerium interstitials and localized electrons. The standard enthalpies of formation for the following defect reactions in Ce~ +yO~ were determined (a) Vi + 5Cece ~ 20o : Cei .... -}-4Ce'ce ~ O2 (g); AHa~ = 10.4 eV +__ 0.3

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Previous analyses of the liquidus and solidus lines in III–V pseudobinary systems are combined and extended. (i) The ideal, strictly regular, athermal, and quasiregular models are investigated for each phase. (ii) A quantitative measure, σ(°C) of a fit is defined and determined. (iii) All sets of values for the parameters of a model giving a value of σ less than a critical value (7°–16°C) characterizing the experimental accuracy are determined and treated on an equal footing. It is found that the strictly regular liquid‐quasiregular solid model is the simplest model giving satisfactory fits for all of the seven systems chosen as the best defined experimentally. Moreover these fits are obtained over a range of values of the three model parameters. As a consequence, thermodynamic properties of the liquid are not closely specified by the analysis. In contrast, for the solid at one temperature, T=m , we find normalΔGmnormalxs=false(b±200false)y1y2 , where the y's are mole fractions and m and b are determined from the fits: m and b are correlated to the properties of the III–V components, and m normalis 0.98±0.03 of the average of their melting points while, within ±250 normalcal,b is proportional to the sixth power of the fractional difference in their lattice parameters. Three of four other systems with data satisfy these correlations. Seven others with no data are discussed. The stability of a quasiregular phase is discussed and the conditions for the formation of normal and “inverted” miscibility gaps established.