Chapter thirteen - Determination of pressure-dependent phase diagrams

Abstract

High pressure is an important physical variable affecting properties of materials almost as significantly as high temperature. High pressure is being used more and more to synthesize new materials, to study the behavior of existing materials, and to tune material physical properties. This chapter describes the currently used high-pressure techniques in the field of high-pressure science. Although there are relatively few studies involving the simultaneous use of pressure and temperature, the importance of such a combination requires that the progress made recently in such experimentation is also considered. The chapter focuses on techniques that are useful from low to ultra high pressures and which permit the in situ characterization of materials. The chapter describes the diamond-anvil cell (DAC) and the large-volume press (LVP). The sample volume in DAC is small but it is a handy tool for rapid exploration of pressure–temperature space and the identification of new high-pressure phases, through in situ studies of their structure and properties. It can also be used to determine rapidly whether a high-pressure phase remains stable on release of pressure. LVP is not as handy as DAC, but it has a very reliable performance and can be easily automated.