Recently there has been a lot development in high-pressure work in physics. The quality of hydrostatic pressure is an important factor. In this article recent advances in the high-pressure apparatuses for precise experiments are reviewed. A piston-cylinder cell, opposed-type anvil cells, and a cubic-type anvil cell are described.
In this article, various materials used for the fabrication of high-pressure apparatus are reviewed. Stresses working on each part of the apparatus are considered and a guideline for the selection of suitable materials is given on the basis of their mechanical and physical properties. Especially, the relation of the material strength to the generated pressure is explained in the case of the piston-cylinder type high-pressure clamp cell. It is also emphasized that the processing is important for the materials strength and the performance of high-pressure apparatus. In connection with recent topics of the Ni-based Russian alloy (NiCrAl alloy) and MP35N, some of their materials properties are introduced.
Guidelines for constructing piston-cylinder type high-pressure apparatuses are presented. We start with numerical analyses on the strength of the cylinder, followed by a choice of suitable materials and strengthening the cylinder beyond what is indicated by the analyses. Some sophisticated techniques in machining the cylinder as well as operating the apparatus are also described.
The fundamental techniques in maintaining pressure (or in preventing pressure medium leaks) are reviewed for many types of high-pressure apparatus. The application of the techniques to generate high pressure is also described for several kinds of pressure media such as liquid or solid. It is emphasized that a new technique to maintain high pressure is the most important aspect when we design new high-pressure apparatus.
History and the technique of the uniaxial compression (stress or strain method) are described. Stress method allows expansion along the two other directions, while the strain method does not. Traditional pressure cell (clamp type for example) can be used for strain method. The important points in the method of uniaxial compression are i) how the chemical reaction between the medium and the sample is avoided and ii) the temperature and pressure of the solidification of the medium. The second point is very important to obtain either ideal hydrostatic or uniaxial pressure. In this respect, even the conventional pressure medium such as Daphne7373 and Fluorinert 70:77 should be reconsidered depending of the pressure and temperature range. At the end, we noted some example of physics phenomena, which are enhanced by uniaxial compression compared with hydrostatic pressure, or which are not realized by hydrostatic pressure but only by uniaxial compression.
We constructed a hybrid piston cylinder-type high-pressure cell using a homemade NiCrAl alloy. It was designed as a hydrostatic pressure cell; 67 mm in length with an outer diameter of 25 mm to be used with a dilution refrigerator. We have succeeded in the resistivity measurement under hydrostatic pressure up to about 3.8 GPa at temperatures down to T = 33 mK without any trouble.
Helium is the best hydrostatic pressure-transmitting medium. A gas-loading system has been constructed to load diamond-anvil cells with high-pressure helium gas at room temperature. In this article, the gas-loading system and high-pressure powder x-ray diffraction experiments with a helium-pressure medium are reviewed.
15 years have passed since we started to develop techniques for the complex extreme condition of very low temperature and ultra-high pressure. In this article our experimental results are briefly reviewed with rather informal stories which are, however, closely related with our research work.
Computer simulation increasingly plays an important role in high-pressure study of condensed matter. I briefly review the methods for atomistic simulation of materials especially focusing on the molecular dynamics method and the treatment of the electron many-body problem.
Supercritical crystallization techniques have advanced in recent years with increasing applications covering a wide variety of chemical processes. Pharmaceutical materials processing with supercritical crystallizations is a relatively new and efficient approach to prepare high purity and micron-sized particles. In this article, the solubility characteristics of organic compounds in supercritical fluids and the applications of the supercritical crystallization techniques to pharmaceutical materials processing are reviewed.
Rapid expansion of supercritical solution (RESS) is a newly developed technology to prepare fine particles or thin films, where a supercritical fluid with dissolved solute is sprayed through a nozzle into a lower pressure space. The RESS process is characterized by high supersaturation and by rapid homogeneous nucleation. The fundamental features and the application feasibility of the RESS process are described. An inorganic material processing with metal alkoxide in supercritical carbon dioxide is mentioned as well as organic materials processing.
This article reviews and discusses fundamental structures and hypotheses of a practical high-pressure scale, which is based on the shock-compression data of some standard materials. In general, these data essentially involve many problems from a microscopic point of view and need some additional thermodynamic and anharmonic parameters to complete any analysis.