The basics of Raman scattering and their experimental techniques under high pressure condition were reviewed in this article. The experimental arrangements which were established for high quality measurements of Raman spectra of the sample in the diamond anvil cell were described in detail. Using the established system, Raman studies were performed on halogens and clathrates, and the results were reported.
This article reviews our techniques for obtaining information about the electronic structures of materials under high pressure using infrared spectroscopy. In our experiment, high pressure up to 20 GPa is generated by a diamond anvil cell (DAC). To perform a reliable infrared study in the limited sample space of a DAC, synchrotron radiation at SPring-8 is used as a bright infrared source. With our technique, it is possible to perform reflectance studies of a single crystal sample, rather than powder samples, in a DAC both in the mid- and far-infrared ranges, and to obtain the optical functions such as optical conductivity and dielectric function under high pressure. To illustrate the capability of our method, actual results of high-pressure infrared studies on strongly correlated f-electron compounds are discussed.
The recent decade has seen dramatic progress in determining the sound wave velocities under extremely high pressures. This advancement enables us to successfully determine the shear wave velocities of constituent mineral phases in the Earth's mantle and the glass materials in situ under high pressures. Here, the recent advances in high pressure elastic wave velocity measurements using Brillouin scattering spectroscopy were reviewed. The continued development of the high-pressure Brillouin scattering spectroscopy promises major advances in exploring the mineralogical model of the Earth's interior, and the high-pressure material science.
In this article, the possibilities of the applications of XAFS (X-ray absorption fine structure) to the high-pressure measurements are discussed. XAFS is a unique technique for the local structure analysis with element selective method for liquids, amorphous and crystalline solids, thin films, surfaces, and nanoparticles. Various examples of XAFS studies for materials science; nanoparticles, magnetic alloys and their transition, ferroelectric materials and the structural transition, molybdenum polyanion, chemical reaction, are presented, in which several elements are included in the system so complex interactions play important roles in the structural, electrical, magnetic and chemical dynamics. The future perspectives of the high-pressure XAFS study for such unique systems are proposed.
X-ray absorption spectroscopy including X-ray magnetic circular dichroism is a useful tool to obtain information of the electronic states and local structure for target elements. Pressure is one of the important thermodynamic parameters so as to observe physical interests of magnetic materials such as metal-insulator transition, magneto-volume effects, and quantum criticality phenomena. In addition, the X-ray absorption spectroscopy under extremely high pressure above 100 GPa is an effective method because the sample volume is too small to perform macroscopic measurements. In this paper, the recent technical methods for X-ray absorption spectroscopy under high pressure are presented, and recent topics for high-pressure research are reviewed.
This review paper introduces inelastic x-ray scattering (IXS) for phonon observations, explains its experimental techniques, and discusses future prospect of this spectroscopic method from the viewpoint of high-pressure materials science. Several studies for elastic property measurements by IXS are shown.
In this article, we describe an unique technique for electrical insulation of metallic gasket to perform simultaneous measurements of electrical resistivity and neutron diffraction under high pressure. The anodic oxide coating was adopted as the insulation layer of the aluminum (JIS A2017) gasket used in the hybrid-anvil device for neutron diffraction. In the feasibility tests of the coated gaskets, maximum pressure of about 6 GPa was generated without electrical breakdown of the coating or disconnection of Au leads.