Phase high-pressure experiments

Tatsumi Y, Hamilton DL, Nesbitt RW, (1986) Chemical characteristics of fluid phase released from a subducted lithosphere and origin of arc magmas evidence from high-pressure experiments and natural rocks. J Volcanol Geotherm Res 29 293-309... 

Roy and Romo (1957) and Boettcher (1966) performed high pressure experiments on natural vermiculites. They observed the production of a 14 X chlorite between 300 and 550°C, talc + enstatite and an unidentified phase above 650°C. The experiments on natural minerals indicate that vermiculite will occur when alkali content or activity in solution is low. This trioctahedral expanding phase is relatively stable at high pressures and temperatures as are interlayered minerals which are composed in part by such layers. It is not stable relative to montmorillonite at low emperature. 

Gas-phase experiments at 100°C. were made up and analyzed as described above. In the high pressure experiments the reacted mixture... 

Parts prepared of h-BN as well as c-BN are of great interest for industrial applications but also for materials science. The thermodynamic data for c-BN and the BN-phase diagrams found in literature are not in agreement. After the first high pressure experiments the B-N phase diagram was designed, and after some modifications c-BN was described as metastable phase at room temperature. Contrary to this opinion in 1988 it was reported that c-BN is the stable phase. Many experiments have confirmed this result, but exact thermodynamic data are still not available. 

In addition to the contributions to understanding the Earth s interior from geophysical evidence and the geochemistry of solar system materials, and from very high-pressure experiments, an important contribution comes from attempts to calculate the effects of pressure on crystal and electronic structures of appropriate materials using quantum-mechanical methods. Some examples of this approach will now be considered, with reference to the phases thought likely to dominate the interior of the Earth. 

For mechanistic studies, ambient pressure experiments on emulsions and foams often offer significant experimental advantages over high-pressure experiments. However, high-pressure measurements are also needed since the phase behavior, physical properties of the fluids, and dispersion flow may all depend on pressure. Experiments under laboratory conditions that closely match reservoir conditions are particularly important in the design of projects for specific fields. Chapter 19, by Lee and Heller, describes steady-state flow experiments on CO2 systems at pressures typical of those used in miscible flooding. The following chapter, by Patton and Holbrook,... 

Boehler R. (2000) High pressure experiments and the phase diagram of lower mantle and core materials. Rev. Geophys. 38, 221-245. 

Rubie D. C. (1999) Characterising the sample environment in multianvil high-pressure experiments. Phase Trans. 68, 431-451. 

How water is transported into the mantle and the depths to which it can be carried have been investigated in high-pressure experiments. In brief, these show that whilst hydrous phases in basalt and subducted sediment can transport water down to the top of the transition zone at about 410 km, hydrous phases in mantle peridotite are capable of transporting water even deeper, certainly into the lower mantle and maybe into the core. 

Figure 11. Phase diagram of carbon disulfide, showing several reaction zones at high pressures and temperatures. The pressure-temperature conditions of various shock wave experiments are also reproduced to highlight the similarity observed in reaction products between shock and static high-pressure experiments.

Acetylene has been observed in the atmospheres of Jupiter and Titan [33, 34] and more recently has been identified in significant abundance in comet Hyakutake [35]. Following the discovery of acetylene in Hyakutake, photochemical experiments have demonstrated [36] that this molecule is a likely precursor of C2, a widely observed component of comets. Acetylene itself may therefore be a ubiquitous constituent of comets. It has been proposed [37] that polymerization of acetylene in cometary impact on planetary atmospheres may be responsible for the formation of polycyclic aromatic hydrocarbons (PAHs) which may in turn be responsible for the colors of the atmospheres of Jupiter and Titan. Shock-induced polymerization of acetylene has been observed in the gas phase [38], and static high-pressure experiments have demonstrated polymerization of orthorhombic solid acetylene above 3 to... 

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