High pressure: a feasible tool for the synthesis of unprecedented inorganic compounds

Pressure can shorten the distance between molecules or atoms, which can change the periodicity of elements and provide more unprecedented novel materials. In order to produce substances that can remain stable or metastable under an atmospheric pressure, pressure has become an indispensable and powerful means. Recent research suggests that high-pressure synthesis methods have unlimited potential in different research fields. For example, highT(c)(transition temperature) superconductors with a transition temperature of up to 250 K and super-hard nano-diamonds (NDs) with a hardness of 1 TPa can be synthesized under high-temperature and high-pressure (HTHP) conditions, and these materials cannot be achieved by other synthetic methods. Many recent research achievements involve the synthesis of some compounds with special structures and properties, such as high-entropy alloys, non-stoichiometric substances, inert element compounds, and heterostructure nanocrystals. This review will introduce the latest developments in inorganic compounds obtained under high pressure. Materials with different application backgrounds are classified, some materials with high performance or high potential are introduced, and possible synthesis mechanisms are discussed. In the Conclusions section, we summarize research directions in which the field of high-pressure synthesis research may have great breakthroughs in the next few years, and look forward to the future development of high-pressure synthesis methods.