Chapter 5 - High Pressure Synthesis and Preparation of Inorganic Materials

Abstract

Ultrahigh pressure inorganic synthesis is a very effective method for synthesizing new inorganic compounds that cannot be obtained under normal conditions. The inorganic compounds synthesized under these high-pressure conditions can have special valences, unique structures, and unprecedented physical and chemical properties. Ultrahigh pressure is a very important research method for physics, chemistry, and material synthesis because it can efficiently change the atomic distances and electron states of the substances. It can therefore be used to tune atomic distances, to probe for information, and to aid in other special areas of the most frontier research; even the periodic table of elements is considered to be rewritten under ultrahigh pressure conditions. Pressure, as a thermodynamic parameter, has extreme influence on substances. Pressure is one part of the Gibbs energy equation, which, along with temperature, controls chemical reaction and phase transition. Ultrahigh pressure develops another dimension of reaction parameter and increases the possibility of the chemical reaction. With the advances of high-pressure technique, ultrahigh pressure is not only an experimental method or extreme condition, but also the third physical parameter along with temperature and chemical stoichiometry. When ultrahigh pressure technique is applied to inorganic synthesis, there are some amazing physical changes (electrical conductivity, optical absorption, and magnetic properties in addition to the densification of the solid).