Quasi-stability

The unique features of chalcogenide glasses (Chap. 6), such as quasi-stability, photoconductivity, infrared transparency, non-linear optical properties, and ionic... 

Redox reactions. The redox chemistry of N is complicated by kinetic factors. These influences give quasi-stability to numerous species which are thermodynamically unstable. This is well illustrated by the action of HNO3 on metals, which is described above in Section 2e. Changes in the metal, the concentration of the acid, the temperature of the reaction, and the presence of various impurities can alter the products, often resulting in mixtures of various species. 

From the observation that N-(mcLhylcnc)morpholinium cations (17) induced the autocatalytic decomposition of tertiary amine W-oxides in combination with the proof that these intermediates were actually present in Lyocell dopes, the question arose why Lyocell solutions were stable at all. The answer is found in the fact that carbenium-iminium ions generated are immediately consumed by reaction with water and carbohydrate structures as the most abundant and most reactive nucleophiles present. Only when the local concentration of 17 increases to such a high level that the consumption by reaction with water or cellulose cannot compensate for its production, does the reaction with NMMO become uncontrollable and lead to an exothermic event. The pulp used in the Lyocell process acts as a quasi-stabilizer for the solvent NMMO, albeit with the drawback of increased chromophore generation. 

J,fc TDA) decoupling. Because of multiple points of quasi-stability for many trajectories, the quasi-stable value of the resonant pole is elicited from the corresponding a trajectory in fig. IS. 

Figure 2-46. Sichematic quasi-stability diagram based on Eq. (2-68). is tbe pressure of tbe metal cblo-...

Static quasi-stability diagram pMeCl = 10 bar Solid, liquid and gaseous phases, but v = 0 and no geometry influence... 

Comparison of the conventional stability diagram (left), the "static" quasi-stability diagram (middle), and the "dynamic" quasi-stability diagram (right) for iron at 800 C (for explanation see text). 

Schematic of the three situations that are used for the assessment of metal chloride evaporation, (a) Vapor pressure of the gaseous metal chloride above solid or liquid metal chloride in a closed system (value used in Equation 13.23 and for determining T ). (b) Equilibrium partial pressure of pMe Cl in a closed system containing O2 and CI2 as gas phase and Me, Me Oj, and Me,.Cly as solid or liquid phases (value used for the establishment of the "static" quasi-stability diagram), (c) Mej.Cly transport rate in the gas boundary layer (metal consumption rate) as criterion for the amount of chlorine-induced corrosion in an open system with gas flow across the surface (value used for the establishment of the "dynamic" quasi-stability diagram).

Dynamic quasi-stability diagram for Fe at 500 C. Zones 1-4 correspond to those in Figure 13.29. (From Latreche, H. et al Oxid. Met., Tl, 1,2009.)... 

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