High pressure solid phase

In addition to high pressure, solid-phase and microwave assistance, a number of less common and rarely occurring methods have been introduced into the field of domino reactions. 

Brown J. M. (2001) The equation of state of iron to 450 GPa another high pressure solid phase Geophys. Res. Lett. 28, 4339-4342. 

The AAP approach, with some variations, has recently been applied with varying degrees of success to the prediction of several other structures including, in order of increasing molecular complexity, high pressure solid phases of benzene [73], the three polymorphs of sulfanilamide [74], and the low and high temperature phases of poly(p-hydroxybenzoic acid) [75]. 

At high pressures, solid II can be converted (slowly) to solid III. Solid III has a body-centered cubic crystal structure. Line bd is the equilibrium line between solid II and solid III, while line be is the melting line for solid III.P A triple point is present between solid II, solid III, and liquid at point b. Two other triple points are present in this system, but they are at too low a pressure to show on the phase diagram. One involves solid II, liquid, and vapor while the other has solid I, solid II, and vapor in equilibrium. 

Stewart, J. W., Proc. 7th Int. Conf. Low Temp. Phys. (Toronto), 1960, 671 Dining the study of phase transitions of solidified gases at high pressures, solid fluorine reacted explosively with apparatus made from stainless steel. 

High-pressure solid-liquid phase equilibria... 

At high pressures, this phase diagram becomes much more complicated than is shown in Figure 24.4. It then features many different forms of solid ice etc. However our basic predictions above are upheld well at modest pressures. The predominant feature of the phase diagram for water (case (ii)) which differs from those displayed by normal substances (case (i)) is that the gradient of the solid / liquid line (AD) (dP/AT < 0) whilst normally (case (i)) it is positive (AP/AT > 0). 

For chemical applications, vibrational spectroscopy of high-pressure fluid phases, including liquids and compressed gases, is of special importance (Buback, 1991). The fluid, i.e., the non-solid region of a substance, is illustrated in Fig. 6.7-2. The packing density of the circles is approximately proportional to the density of a substance. The bottom left part of Fig. 6.7-2 shows the vapor pressure curve which, up to the critical point, separates the liquid phase from the gas phase. Above the critical temperature (7 ), the density of a substance may change continuously between gaseous and liquid like states vibrational spectroscopic methods make it possible to study the structure and dynamics... 

Szafranski, M., Czarnecki, R, Katrusiak, A. and Habrylo, S. (1992). DTA investigation of phase-transitions in 1,3-cyclohexanedione under high-pressures. Solid State Commun., 82, 277-81. [239]... 

Liau, I. S., and M. A. McHugh. 1985. High pressure solid polymer-supercritical fluid phase behavior. In Supercritical Fluid Technology, ed. J. M. L. Penninger, M. Radosz, M. A. McHugh, and V. J. Krukonis, 415. New York Elsevier. 

The design criteria for high-pressure probes for solid-state NMR are, in general, different to those for liquid- or gas-state NMR. On the one hand, more extreme conditions of temperature and pressure are often needed to study, for example, structural phase transitions. On the other hand, the NMR resonances in solids are normally extremely broad compared to those in liquids, so that high resolution is no longer a primary consideration. We present here two designs of probe that demonstrate these different criteria, and show state-of-the-art high-pressure solid-state NMR apparatus. 

A more recent development is the use of formed plastics, especially opencell type resilient polyurethanes, for the separation and/or preconcentration of trace species from water samples. The main advantages of these materials are a quasimembrane structure which allows rapid solid/liquid or solid/gas contact in column operation and the ability to immobilize a variety of reagents as collectors and so act as a highly versatile solid phase support. The resilience of these foams permit their use in special modes such as automated batch pressure or pulsating column operation [10]. 

Fig. 8. Reduced volume of the high-pressure Si phases. Experimental points are from Reference [67] (Si-I and Si-II) and Reference [63] (Si-III and Si-XII). Filled and open circles correspond to increasing and decreasing pressure, respectively. The solid lines are fits to the 3rd-order Birch equation of state [69, 70] with the values of bulk modulus Bq = 108 GPa and its first pressure derivative Bq = 4 for Si-I Bq = 117 GPa for Si-Ill and Bo = 108 GPa for Si-XII with Bq fixed at 5. Dashed line serves as a guide to the eye.

Sections 9.3-9.S present the common phase behavior of binary mixtures 9.3 describes vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibria at low pressures 9.4 considers solid-fluid equilibria and 9.5 discusses common high-pressure fluid-phase equilibria. Then 9.6 briefly describes the basic vapor-liquid and liquid-liquid equilibria that can occur in ternary mixtures. This chapter describes many apparently different phase behaviors, and so we try to show when those differences are more apparent than real. The organization is intended to bring out underlying similarities, thereby reducing the number of different things to be learned. 

The pressure difference between the liquid-solid equilibrium curves for pure and impure materials corresponds to the freezing temperature depression caused by the presence of an impurity. The pressure increase accompanying the increase in pure crystalline material deposited is related to the concentration of impurities in the liquid. With this information, therefore, the mother liquor composition at any stage can be estimated from the system pressure. Consequently, a highly pure solid phase can be obtained by separating the liquid phase from the solid phase while maintaining an appropriate pressure corresponding to the desired solid fraction or mother liquor composition. 

Hayashi J, Shirotani I, Hirano K et al (2003) Structural phase transition of ScSb and YSb with a NaCl-type structure at high pressures. Solid State Commun 125 543-546 Shirotani I, Yamanashi K, Hayashi J et al (2003) Pressure-induced phase transitions of lanthanide monoarsenides LaAs and LuAs with a NaCl-type structure. Solid State Commun 127 573-576... 

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