High-pressure synthesized materials: treasures and hints

Abstract

The present review covers the production of new materials under high pressures. A primary limitation on the use of pressures higher than 1 GPa is a small volume and mass of a produced material. Therefore, despite an extremely wide range of new high-pressure synthesized substances with unique properties, synthesis on an commercial scale is applied up to now only to obtain superhard materials, this real treasure of today's industry. At the same time, high-pressure experiments often give material scientists a hint at what new intriguing substances can exist in principle. This is true for new superhard, semiconducting, magnetic, superconducting and optical materials already synthesized under pressure, and as well as for a large number of hypothetic new polymers from low-Z elements. Many of new materials, including the above polymers, may exist in the metastable form at normal pressure at sufficiently high temperatures.Keywords: high pressure, materials synthesis, metastable phases 1 IntroductionThe synthesis of materials under high pressure is a vast area of physics, chemistry and engineering. Should you browse the Internet to search "high pressure synthesis", the web search engines, for example, Google, would respond with over 10 mln links, making it absolutely impossible to write any comprehensive review on this topic. For this same reason, neither it is possible to list all relevant references. The purpose of this paper is to present the author's personal view on the state of art and prospects of the production of new materials by using highpressure synthesis, and to complement already existing reviews, for example [1,2]. It should be noted that a number of publications, for example [2], discuss a comparatively narrow range of materials synthesized under pressure. Other publications, for example [1], also focus on anomalous properties of materials in a strongly compressed state, although most of materials with such properties cannot be retained at normal pressure, hence, they are not directly related to the subject under consideration. In addition, the behavior of materials in a strongly compressed state has also been extensively covered in scientific literature (for example, see [3]).For physicists, the history of a high-pressure research is first of all associated with P.W. Bridgman, a 1946 Nobel Prize Laureate "for the invention of an apparatus to produce extremely high pressures, and for the discoveries he made therewith in the field of high pressure physics". Nowadays high-pressure synthesis of new materials is primarily associated with a successful synthesis of superhard materials -diamond and cubic boron nitride -in the second half of the 20 th century. At the same time, the pressures 1 -10 3 MPa have been already in use for more than a century in chemistry for the industrial production of materials. What's more, the development of relevant engineering procedures has been more than once rewarded with a Nobel Prize in chemistry. In 1918, F. Haber won the Nobel Prize "for the synthesis of ammonia from its el...

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