Phase diagram determination

Sodium-zinc alloys for phase diagram determination are prepared by melting the elements in glass tubes under H2- Samples of NaZujj are prepared by heating zinc for several hours above the melting point of NaZn,3 (557°C) with xs Na in alundum extraction thimbles with N2 or Ar in a steel bomb scaled with copper gaskets. Excess Na was removed by extraction with liq NHj. Both KZn,3 and KCd,2 were prepared in this manner. ... 

The Sr-Cu system has been critically assessed. The most recent phase diagram, determined by combining differential thermal analysis and x-ray diffraction techniques, contains two intermediate compounds, both of which form in peritectic reactions, SrCu (588°C) and SrCu, (845°C) SrCu has also been prepared for independent structural analysis-. ... 

Ataka, M. (1993). Protein crystal growth An approach based on phase diagram determination. Phase Transitions 45, 205-219. 

A final caveat that must be applied to phase diagrams determined using DFT calculations (or any other method) is that not all physically interesting phenomena occur at equilibrium. In situations where chemical reactions occur in an open system, as is the case in practical applications of catalysis, it is possible to have systems that are at steady state but are not at thermodynamic equilibrium. To perform any detailed analysis of this kind of situation, information must be collected on the rates of the microscopic processes that control the system. The Further Reading section gives a recent example of combining DFT calculations and kinetic Monte Carlo calculations to tackle this issue. 

Fig. 3.28 Phase diagram determined from computer simulations of an ABA triblock copolymer with Nr — 10 in a selective solvent for the B hlock and insoluble end blocks (Nguyen-Misra and Mattice 1995a).

FIGURE 7.4 Partial solubility phase diagram determined by dilution experiments on a 1 1 diastereoisomeric mixture (dashed line). 

Figure 9. Temperature-composition phase diagram of the system pentaethylene glycol ether (C12E5), water, and n-octane. The weight ratio of water to octane is fixed at 60 to 40. Diffusivities were measured in samples denoted by filled circles. Phase diagram determined by Kahlweit et al. Reprinted with permission from Kahlweit et al. [11],...

Experimental phase-diagram determination involves the preparation of a large number of samples spanning the entire compositional range, identification of aU the phases present for each temperamre/composition point, and the careful measurement of thermodynamic properties as well as phase transformation temperatures. Accordingly, a variety of experimental techniques is typically utilized in any one case. 

Ternary System Phase Diagram Determinations Concerning Potassium Electrolyte Influence on Aqueous Solutions of Dioxane or T etrahy drof uran... 

B. O. Cullity and S. R. Stock, Elements of X-Ray Diffraction , 3rd Edition, Prentice Hall, Upper Saddle River, 2001, Excellent treatment of powder methods in general. Includes phase-diagram determination, polycrystalline aggregates, polymers, quantitative analysis and stress analysis. 

Figure 4. Comparison of the phase diagrams determined from the refractive index measurements with that obtained by the visual method. The weight fraction w is the concentration variable. Empty symbols are used, when the compositions are estimated from refractive index data (Cemim+BFJ in 1-butanol (A), 1-pentanol (y), 2-butanol (0), and 2-pentanol (<)), full symbols, when the data are obtained by the visual method observing the separation temperature in samples of different composition (Gemini+ in water ( ), 1-propanol (O). 1-butanol (A), 2-butanol (y), 1-pentanol (0), 2-pentanol (<), and 1-hexanol (>)).

Phase Diagram Determination. Phase diagrams were determined from equilibrated mixtures of MMA, alcohol and aqueous SLS solutions. 

The general principles of phase-diagram determination are described by Taylor [G.19], with special emphasis on x-ray methods. 

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