This paper will be concerned with those aspects of the pressure-induced effects and phase transitions in molecular and tetrahedrally bonded semiconductors. First, we discuss the pressure effects on the lattice vibrations in alloy and amorphous solids. Second, we discuss the pressure effects on the electronic band structure and gap states in alloys and superlattices. Third, we discuss the insulator-metal transitions in some molecular solids and tetrahedrally bonded semiconductors.
Many of the thermophysical properties of fluids are greatly altered at high pressures, and the study of the effects of temperature and pressure on these properties is of much scientific and technological importance. The definition, classification and character of thermophysical properties are discussed, as well as the philosophy in their researches. The general behavior of the typical properties with temperature, pressure and density is summarized in both gaseous and liquid phases. Some anomalous phenomena are also reviewed briefly. The present status of the database systems is referred for the practical use of the thermophysical property information.
An overview of the current international standards on various thermophysical properties of water and steam, which have been prepared and authorized by the International Association for the Properties of Water and Steam (IAPWS), is presented. A long traditional international collaboration over 62 years in this field has been established throughout the International Conferences on the Properties of Steam (ICPS) which are used to be organized by the International Association for the Properties of Steam (IAPS), the former organization of the present IAPWS. The paper provides some brief historical reviews on the outstanding activities through the ICPS, IAPS and currently-existing IAPWS, which all have been achieved on the basis of international cooperations. Some detailed discussions on the existing documents such as Releases, Supplementary Release and Guidelines disseminated as a set of international standards on various thermophysical properties of water and steam by the IAPWS are included for aiming the extensive applications by the readers.
Current interest of high-pressure earth scientists is shifting from upper mantle to lower mantle, from mantle to core, from quenching experiments to high-pressure, high-temperature in-situ measurements, and from static phase equilibrium to large scale dynamical motion. In this paper, frontier report is given on several topics. A precise version of the olivine-modified spinel-spinel-post spinel transformation diagram in the system Mg2SiO4Fe2SiO4 and of the pyroxene-garnet-ilmenite-perovskite transformation diagram in the system Mg4Si4O12-Mg3Al2Si3O12 is presented. The 670km seismic discontinuity is well-explained by the dissociation of (Mg, Fe) 2SiO4 spinel to (Mg, Fe) SiO3 perovskite and (Mg, Fe) O magnesiowüstite in pyrolitic mantle. Based on the phase diagram, the temperature at the depth of 655km is estimated about 1600°C. Effect of the olivine-modified spinel-spinel-post spinel transformations on the dynamics of the descending slab (plate) is discussed in relevance to the deep focus earthquakes. Recent progress of high-pressure, high-temperature research in the system Fe-H, Fe-FeO and Fe-SiO2 is outlined with reference to the core formation process in the proto-earth and the composition of the present earth's core. Solubility of hydrogen, oxygen and silicon into molten iron increases remarkably at very high pressure up to 24 GPa. Oxygen and hydrogen might be the chief light elements in the earth's outer core. The silicon content in the core depends on the depth of the magma ocean of the proto-earth.
Since the first success in diamond synthesis by using transition metals such as Fe, Co, Ni and their alloys as diamond-producing catalysts under very high temperatures and pressures, inorganic compounds such as carbonates have also been expected as the catalysts. The authors have recently found that diamond can be synthesized from graphite in the presence of the carbonates, sulfates and hydroxides of alkali and alkaline earth metals at about 7. 7 GPa and 2000°C. So far, by using these new catalysts, various kinds of diamond grains could be obtained. Besides, crystal growth of diamond could be realized on the faces of seed diamond crystals at lower pressures and temperatures of about 5. 5 GPa and 1600-1800°C. Diamond powder could be sintered by using alkaline earth carbonates as a sintering aid at 7. 7 GPa and 2000-2450°C.
Excited 37 years ago by the news of the successful synthesis of diamond by General Electric (GE), USA, the team of researchers at the Ishizuka Research Institute (IRI), headed by Mr. Ishizuka who had been interested for years in the same objective, became fully involved in the development of their own technique for a commercial production of diamond. Here is how they could achieve the goal. The IRI researchers began their efforts by tracing the GE technique as published in patents and literature, from scratch by hand-making almost every piece of the tools by themselves, then they struggled to find any way to leap over GE's tight blockage of patents. Their efforts were rewarded when they achieved in the end their original process in which a solvent of Ni-Cr3C2 and the HT-HP equipment including a WC-Co/ceramic double cylinder construction were used. Those techniques were first commercialized by Komatsu Diamond Co. in Feb. 1963.
Safety points for the use of the semiconductor gases in research laboratory are briefly described according to the related clauses in the revised High Pressure Gas Control Law. Those, which should be applied to all of our gas experiments, tell us how the semiconductor gases are safely produced, transported, and consumed on a small-or medium-sized scales in the research laboratory.