The optoelectronics technology will play an important role in the progress of hardware technology. Glasses have long been used as a linear optical material before the discovery of lasers. However, with the availability of very high intensity laser light, the refractive indices of glasses are now known to exhibit reversible changes as a function of intensity (nonlinear optical property NLO). Glassy materials are one of those candidates for photonic switches because of their (1) ease of fabrication, (2) high transparency, (3) fast switching time, and (4) high chemical and thermal stabilities. Main interests in the research are that NLO glass has the potential to become a key material of all-optical switching devices which operate in picosecond or sub-picosecond response time, three orders of magnitude shorter than that of the limit attained by electronic switching devices. Using all-optical switches, optical parallel data processing systems and optical time domain multiplexing transmission systems will be developed in the future. Here, theory and applications of nonlinear optics were reviewed briefly, and the nonlinear optical properties of the glasses doped semiconductor were mentioned. Other optical properties like upconversion, photochromism and photoconduction were also reviewed.

抄録全体を表示

Quartz grains within granitic mylonite from the Median Tectonic Line (MTL) contain significant amounts of water (from 2500 to 10500 ppm) with IR signatures. Most of this water is freezable, and may differ from those within natural vug-grown quartz and synthetic single crystals. Quartz grains in strongly sheared mylonites may contain large number of fine (less than 500 nm in diameter) inclusions along dislocations which bear a resemblance to bubbles developped within heat-treated wet synthetic quartz. This water within extremely fine inclusions may be effective for the hydrolytic weakening of rocks within the earth's crust.

抄録全体を表示

Mantle olivines contain small amounts of hydrogen, structurally bound as hydroxyl, and constitute a possible reservoir for water in the mantle. The SIMS analyses showed the hydrogen concentration (10 to 60 parts per million H₂O by weight) and the correlation of hydrogen with monovalent and trivalent cations. The content varied with equilibration temperature and pressure of the host rocks. Since the content reflects pre-eruptive hydrogen conditions in the mantle, it is an important clue to understanding rheological feature and magmatic process in the mantle.

抄録全体を表示

Experiments on the reaction between forsterite and Si-rich gas were carried out in a vacuum furnace by using a newly designed double-capsule technique. The reaction plays extremely important role in the fractionation in the primitive solar nebula. The reaction is controlled by diffusion of elements in the enstatite layer. The degree of the reaction of forsterite with Si-rich residual gas in the primitive solar nebula is discussed based upon the measured reaction rate, and it is suggested that very little enstatite was formed by this reaction in the cooling nebula, if the grain size of the forsterite crystals was controlled by homogeneous nucleation theory.

抄録全体を表示

Experimental studies on olivine dissolution and ion exchange reaction were performed to understand reaction mechanism and kinetics. In the dissolution experiments, olivine crystals (Fo91) were water treated at 25°C under different pH conditions. X-ray photoelectron spectroscopy and resonant nuclear reaction analysis revealed the different characteristic features of the surface layer with the thickness of 10 to 20 nm depending on pH. The rate controlling step seems to be Si detachment under low pH conditions and Mg detachment under high pH conditions respectively. The ion exchange experiments between olivine (Fo91) and FeCl₂ solution were carried out at 600 to 800°C, 1 kb. Scanning electron microscopic observation and chemical analysis showed that the reaction front advances with precipitation/dissolution mechanism.

抄録全体を表示

The alteration of trioctahedral micas (biotite, phlogopite, etc.) have been the subject of many studies on weathering and hydrothermal alteration, because they are common rock-forming minerals and act as an important source of soluble K in soil. In this paper, the dissolution process of micas and the formation mechanism of alteration products such as vermiculite, chlorite and kaolinite in the alteration process of micas are reviewed briefly.

抄録全体を表示

It is very difficult to investigate the behaviour of smectite and related clay minerals, because they are fine particles and low crystallinity. There are two ways to clarify their behaviour. One is the characterization by microscopic analyses: TEM, SEM and others. The other is the synthesis of large single crystal of smectite and that of related clay minerals. The former is supported by the recent progress in the analytical methodology and is successful partially in the last decade. The latter, to prepare a single crystal of smectite, is just recently realized in the author's research group using non-equilibrium condition, that is, quenching process of a high-pressure and high-temperature hydrous melt. In the future, the real behaviour of smectite and that of related clay minerals will be solved by the combination of these approaches.

抄録全体を表示

Recent developments in high-pressure crystal chemistry of certain rock forming minerals of the earth's mantle are reviewed and several problems are suggested to be investigated in regard to the crystal structure-compressibility systematics. Empirical relationships between the bulk modulus and the crystal structure are reviewed in Sec. 2. The effect of Fe on the bulk modulus of several mantle minerals are reviewed in Sec. 3. The empirical equations for the bond compressibility are reviewed and discussed in Sec. 4.

抄録全体を表示

Recent developments in calorimetric techniques have enabled us to measure enthalpy and entropy of transitions of high pressure minerals with sufficient accuracy. These thermodynamic data are used to calculate accurately the stability relations of mantle minerals at high pressures and high temperatures. Our new thermodynamic data on MgSiO₃ perovskite, the most abandant phase in the lower mantle, are applied to calculating the dissociation boundary of spinel to perovskite plus periclase and to estimating temperature profile in the lower mantle. Implications of the calculated boundary slope on the mantle dynamics are discussed.

抄録全体を表示

Perspective on mineralogy in 21st century was reviwed briefly. There may be some important view points for development of mineralogy, especially in Japan: Understanding minerals in process and behaviour within the Earth and the solar system, understanding of natural laws or rules unique to mineral, which may be possible especially in relation to mineralogy as a part of earth science, regarding natural mineral as important, establishing modern view on mineral, enlightening mineral science more widely, having good textbook of mineralogy, and so on.

抄録全体を表示