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Hydrothermal synthesis includes the various techniques of crystallizing substances from high-temperature aqueous solutions at high vapor pressures; also termed "hydrothermal method". The term "hydrothermal" is of geologic origin.〔The earliest occurrence of the word "hydrothermal" appears to be: Sir Charles Lyell, ''A Manual of Elementary Geology'' … , 5th ed. (Boston, Massachusetts: Little, Brown, and Company, 1855), (page 603 ): "The metaphoric theory (us to affirm ) that an action, existing in the interior of the earth at an unknown depth, whether thermal, hydro-thermal, … "〕 Geochemists and mineralogists have studied hydrothermal phase equilibria since the beginning of the twentieth century. George W. Morey at the Carnegie Institution and later, Percy W. Bridgman at Harvard University did much of the work to lay the foundations necessary to containment of reactive media in the temperature and pressure range where most of the hydrothermal work is conducted. Hydrothermal synthesis can be defined as a method of synthesis of single crystals that depends on the solubility of minerals in hot water under high pressure. The crystal growth is performed in an apparatus consisting of a steel pressure vessel called an autoclave, in which a nutrient is supplied along with water. A temperature gradient is maintained between the opposite ends of the growth chamber. At the hotter end the nutrient solute dissolves, while at the cooler end it is deposited on a seed crystal, growing the desired crystal. Advantages of the hydrothermal method over other types of crystal growth include the ability to create crystalline phases which are not stable at the melting point. Also, materials which have a high vapour pressure near their melting points can also be grown by the hydrothermal method. The method is also particularly suitable for the growth of large good-quality crystals while maintaining control over their composition. Disadvantages of the method include the need of expensive autoclaves, and the impossibility of observing the crystal as it grows.〔 〕 ==History== The first report of the hydrothermal growth of crystals〔For a more detailed history of hydrothermal synthesis, see: K. Byrappa and Masahiro Yoshimura, ''Handbook of Hydrothermal Technology'' (Norwich, New York: Noyes Publications, 2001), (Chapter 2: History of Hydrothermal Technology ).〕 was by German geologist Karl Emil von Schafhäutl (1803-1890) in 1845: he grew microscopic quartz crystals in a pressure cooker.〔Schafhäutl (1845) "Die neuesten geologischen Hypothesen und ihr Verhältniß zur Naturwissenschaft überhaupt" (The latest geological hypotheses and their relation to science in general), ''Gelehrte Anzeigen'' (published by: die königliche Bayerische Akademie der Wissenschaften (the Royal Bavarian Academy of Sciences)), 20 : 557, 561-567, 569-576, 577-596. On (page 578 ), he states: "''5) Bildeten sich aus Wasser, in welchen ich im Papinianischen Topfe frisch gefällte Kieselsäure aufgelöst hatte, beym Verdampfen schon nach 8 Tagen Krystalle, die zwar mikroscopisch, aber sehr wohl erkenntlich aus sechseitigen Prismen mit derselben gewöhnlichen Pyramide bestanden.''" ( 5) There formed from water in which I had dissolved freshly precipitated silicic acid in a Papin pot (pressure cooker ), after just 8 days of evaporating, crystals, which albeit were microscopic but consisted of very easily recognizable six-sided prisms with their usual pyramids.)〕 In 1848, Robert Bunsen reported growing crystals of barium and strontium carbonate at 200 °C and at pressures of 15 atmospheres, using sealed glass tubes and aqueous ammonium chloride ("Salmiak") as a solvent.〔R. Bunsen (1848) ("Bemerkungen zu einigen Einwürfen gegen mehrere Ansichten über die chemisch-geologischen Erscheinungen in Island" ) (Comments on some objections to several views on chemical-geological phenomena in Iceland), ''Annalen der Chemie und Pharmacie'', 65 : 70-85. On page 83, Bunsen mentions crystallizing the carbonate salts of barium, strontium, etc. ("die kohlensauren Salze der Baryterde, Strontianerde, etc.").〕 In 1849 and 1851, French crystallographer Henri Hureau de Sénarmont (1808-1862) produced crystals of various minerals via hydrothermal synthesis.〔See: * de Sénarmont (1849) ("Expériences sur la formation artificielle par voie humide de quelques espèces minérales qui ont pu se former dans les sources thermales sous l'action combinée de la chaleur et de la pression" ) (Experiments on the artificial formation from solution of some mineral species that could form in hot springs under the combined action of heat and pressure), ''Comptes rendus'' … , 28 : 693-696 . * H. de Sénarmont (1851) ("Note sur la formation artificielle, par voie humide, du corindon et du diaspore" ) (Note on the artificial formation, from solution, of corundum and diaspore), ''Comptes rendus'' … , 32 : 762-763.〕〔(【引用サイトリンク】 Hydrothermal Crystal Growth - Quartz ) 〕 Later (1905) Giorgio Spezia (1842-1911) published reports on the growth of macroscopic crystals.〔Giorgio Spezia (1905) ("La pressione è chimicamente inattiva nella solubilità e ricostituzione del quarzo" ) (Pressure is chemically inactive in the solubility and reconstitution of quartz), ''Atti della Reale Accademia delle scienze di Torino'' (Proceedings of the Royal Academy of Sciences in Turin), 40 : 254-262.〕 He used solutions of sodium silicate, natural crystals as seeds and supply, and a silver-lined vessel. By heating the supply end of his vessel to 320-350 °C, and the other end to 165-180 °C, he obtained about 15 mm of new growth over a 200-day period. Unlike modern practice, the hotter part of the vessel was at the top. A shortage in the electronics industry of natural quartz crystals from Brazil during World War 2 led to postwar development of a commercial-scale hydrothermal process for culturing quartz crystals, by A. C. Walker and Ernie Buehler in 1950 at Bell Laboratories. Other notable contributions have been made by Nacken (1946), Hale (1948), Brown (1951), and Kohman (1955).〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「hydrothermal synthesis」の詳細全文を読む スポンサード リンク
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