Oxides stability diagram

Uppsala and Northwestern University, thermodynamic calculations were performed using Bi(ph)3, Sr(hfa)itet, Ca(hfa)2tet, and Cu(acac)2 as metal-organic precursors [126]. The experimentally observed phase stability of BSCCO for in situ CVD was in agreement with the calculated thermodynamic oxide stability diagrams [126]. These results indicate that thermodynamic modeling can be used as a guide for the optimization of CVD routes to complex metal oxide films. 

Fig. 7.78 Thermodynamic stability diagram for some oxides and sulphides at 1 000 K (after...

Fig. 7.80 A schematic thermodynamic phase stability diagram for the A-C-O system, showing three reaction paths. Paths 2 and 3 are only possible if gaseous diffusion in pores in the oxide product results in a carbon activity increase through the scale, as shown in Fig. 7.81 (after...

Pourbaix (16) has prepared theoretical stability diagrams of potential vs. pH for many common metals and nonmetalloids. A review of these results indicates that semiconductor compounds of Au, Ir, Pt, Rd, Ru, Zr, Si, Pd, Fe, Sn, W, Ta, Nb, or Ti should serve as relatively acid-stable photoanodes for the electrolysis of water. Indeed, all of the stable photo-assisted anode materials reported in the literature, as of March, 1980 (see Table III) contain at least one element from this stability list, with the exception of CdO. Rung and co-workers (18) observed that the CdO photoanode was stable at a bulk pH of 13.3. The Pourbaix diagram for Cd (16) shows that an oxide film passivates Cd over the concentration range 10.0 < pH < 13.5. Hence the desorption of the product H+ ion for the particular case of CdO must be exceptionally facile without producing an effective surface pH lower than 10.0. This anamolous behavior for CdO is not well understood. 

Because chlorine is widely used as a disinfectant for drinking water, swimming pools, and sewage treatment, it is worth looking at its stability diagram. Note that the effective bactericidal agent is not CI2 itself, but its oxidation product hypochlorous acid HOC1 which predominates at pH values below its pKa of 7.3. Note also that... 

More details of equilibrium models commonly used for gas phase equilibria, mixed phases, isotope effects, oxidation/reduction, electron activity, and pH stability diagrams can be found in Stumm and Morgan (1996) and Butcher and Anthony (2000). 

Aluminum hydroxy species, 65,69,160 Stability constants, 69 Stability diagrams, 78 pH of minimum solubility, 65, 71, 72 Ammonium, 326, 331 Volatilization, 330 Oxidation, 334-336,472 Nitrate, 334-336,472 Adsorption, 336,465-466 Metal-ammine complexes, 460—461, 465... 

The oxidation state diagrams in Figure 1 give a perspective on the relative stability of manga-nese(II) for OH2, OH and O2 ligands. 

The stability diagrams of oxide/hydroxide of aluminum and silicon minerals/ aqueous solution systems are illustrated in Figures 1.6 and 1.7. In these diagrams, the following reactions were taken into account. 

Of course, stability diagrams can be constructed not only for the oxides but for other more complex minerals as well. From these diagrams, the stabilities of the minerals under a given condition can be predicted. 

On the basis of thermodynamic constants obtained for hydroxide compounds of iron with different aging time and also of experimental data, the physicochemical character of the diagenetic transformations of iron sediments of various compositions (oxide, silicate, carbonate, sulfide) can be traced. The results obtained are represented graphically in the form of stability diagrams of iron compounds as a function of variations in the main parameters governing the physicochemical character of the environment of diagenesis—pH, Eh, activity of iron and dissolved forms of sulfur and carbon dioxide. 

Equation (3) can be used to calculate the standard electrode potentials. Calculations based on the Bom-Haber cycle to obtain the relative stabilities of oxidation states are known as Oxidation State Diagrams . These diagrams have been found useful in clarifying inorganic chemistry (69), even though their accuracy is sometimes low. 

In summary, NO Os can be formed via totally different paths with different starting nitrogen oxides. However, unambiguous interpretation of the structure, stability and transformation mechanism involving this peculiar ionic species is unavailable. Therefore, comprehensive experimental means, including x-ray diffraction measurement, Raman and Infrared spectroscopy were employed to understand the fundamental properties of NO Os synthesized via the last path mentioned above. While the diffraction measurements established the P-V equation of state, the optical spectra, especially the low-temperature Raman data, elucidate important aspects of the transformation, thermodynamic properties, and stability diagram of NO Os. ... 

Within the area of interest in the stability diagrams, ferric hydroxide precipitation is possible at lower oxidation potentials than manganic manganese oxides at any given pH. Similarly, at a fixed Eh ferric hydrox-... 

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