The crystal bar process (also known as iodide process or the van Arkel–de Boer process) was developed by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925. This process was the first industrial process for the commercial production of pure ductile metallic zirconium. It is used in the production of small quantities of ultra-pure titanium and zirconium. It primarily involves the formation of the metal iodides and their subsequent decomposition to yield pure metal. This process was superseded commercially by the Kroll process.Dirk Willem van Krevelen
Dirk Willem van Krevelen (8 November 1914, Rotterdam – 27 October 2001, Arnhem) was a prominent Dutch chemical engineer, coal and polymer scientist. He successfully combined an industrial career, managing a research division at DSM, and an academic career, as Professor of Delft Technical College. His contributions span a wide range of research fields, and his name is linked to the van Krevelen–Hoftyzer diagram for chemical gas absorption, the Mars–van Krevelen mechanism for catalytic oxidation reactions, the van Krevelen–Chermin method to estimate the free energy of organic compounds, the van Krevelen diagram that is used in coal and coal processes, the van Krevelen method to calculate additive properties of polymers, and the van Krevelen–Hoftyzer relationship on the viscosity of polymer fluids.He is the author of numerous scientific publications and several classic monographs, amongst which are Coal: Typology, Chemistry, Physics, Constitution and Properties of Polymers: Correlations with Chemical Structure.Group 4 element
Group 4 is a group of elements in the periodic table.
It contains the elements titanium (Ti), zirconium (Zr), hafnium (Hf) and rutherfordium (Rf). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals.
The three Group 4 elements that occur naturally are titanium, zirconium and hafnium. The first three members of the group share similar properties; all three are hard refractory metals under standard conditions. However, the fourth element rutherfordium (Rf), has been synthesized in the laboratory; none of its isotopes have been found occurring in nature. All isotopes of rutherfordium are radioactive. So far, no experiments in a supercollider have been conducted to synthesize the next member of the group, unpentoctium (Upo, element 158), and it is unlikely that they will be synthesized in the near future.Hafnium
Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Coster and Hevesy, making it the last stable element to be discovered. Hafnium is named after Hafnia, the Latin name for Copenhagen, where it was discovered.Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten.
Hafnium's large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.Jan Hendrik de Boer
Jan Hendrik de Boer (19 March 1899 – 25 April 1971) was a Dutch physicist and chemist.
De Boer was born in Ruinen, now De Wolden, and died in The Hague. He studied at the University of Groningen and was later employed in industry.
Together with Anton Eduard van Arkel, de Boer developed a chemical transport reaction for titanium, zirconium, and hafnium known as the crystal bar process. In a closed vessel the metal reacts with iodine at elevated temperature forming the iodide. At a tungsten filament of 1700 °C the reverse reaction occurs, and the iodine and the metal are set free. The metal forms a solid coating at the tungsten filament and the iodine can react with additional metal, resulting in a steady turnover.
M + 2I2 (>400 °C) → MI4
MI4 (1700 °C) → M + 2I2De Boer became a member of the Royal Netherlands Academy of Arts and Sciences in 1940, and foreign member in 1947.List of Dutch discoveries
The Netherlands had a considerable part in the making of modern society. The Netherlands and its people have made numerous seminal contributions to the world's civilization, especially in art, science, technology and engineering, economics and finance, cartography and geography, exploration and navigation, law and jurisprudence, thought and philosophy, medicine, and agriculture. Dutch-speaking people, in spite of their relatively small number, have a significant history of invention, innovation, discovery and exploration. The following list is composed of objects, (largely) unknown lands, breakthrough ideas/concepts, principles, phenomena, processes, methods, techniques, styles etc., that were discovered or invented (or pioneered) by people from the Netherlands and Dutch-speaking people from the former Southern Netherlands (Zuid-Nederlanders in Dutch). Until the fall of Antwerp (1585), the Dutch and Flemish were generally seen as one people.List of chemists
This is a list of chemists. It should include those who have been important to the development or practice of chemistry. Their research or application has made significant contributions in the area of basic or applied chemistry.
Richard Abegg (1869–1910), German chemist
Frederick Abel (1827–1902), English chemist
Friedrich Accum (1769–1838), German chemist, advances in the field of gas lighting
Homer Burton Adkins (1892–1949), American chemist, known for work in hydrogenation of organic compounds
Peter Agre (born 1949), American chemist and doctor, 2003 Nobel Prize in Chemistry
Georgius Agricola (1494–1555), German scholar known as "the father of mineralogy
Arthur Aikin (1773–1855), English chemist and mineralogist
Adrien Albert (1907–1989), Australian medicinal chemist
John Albery (1936–2013), English physical chemist
Kurt Alder (1902–1958), German chemist, 1950 Nobel Prize in Chemistry
Sidney Altman (born 1939), 1989 Nobel Prize in Chemistry
Faiza Al-Kharafi (born 1946), Kuwaiti chemist and academic. She was the president of Kuwait University from 1993 to 2002, and the first woman to head a major university in the Middle East.
Christian B. Anfinsen (1916–1995), 1972 Nobel Prize in Chemistry
Angelo Angeli, Italian chemist
Octavio Augusto Ceva Antunes (1731–1810), British scientist
Anthony Joseph Arduengo, III, American chemist
Johan August Arfwedson (1792–1841), Swedish chemist
Anton Eduard van Arkel (1893–1976), Dutch chemist
Svante Arrhenius (1859–1927), Swedish chemist, one of the founders of physical chemistry
Larned B. Asprey (1919–2005), American nuclear chemist
Francis William Aston (1877–1945), 1922 Nobel Prize in Chemistry
Amedeo Avogadro (1776–1856), Italian chemist and physicist, discovered Avogadro's lawList of rectores magnifici of Leiden University
This is a list of chancellors (rectores magnifici) of Leiden University, as from 1575. Three Nobel laureates are among these chancellors: Hendrik Lorentz, Heike Kamerlingh Onnes and Willem Einthoven.Pnictogen
A pnictogen is one of the chemical elements in group 15 of the periodic table. This group is also known as the nitrogen family. It consists of the elements nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and perhaps the chemically uncharacterized synthetic element moscovium (Mc).
In modern IUPAC notation, it is called Group 15. In CAS and the old IUPAC systems it was called Group VA and Group VB respectively (pronounced "group five A" and "group five B", "V" for the Roman numeral 5). In the field of semiconductor physics, it is still usually called Group V. The "five" ("V") in the historical names comes from the "pentavalency" of nitrogen, reflected by the stoichiometry of compounds such as N2O5. They have also been called the pentels.
The term pnictogen (or pnigogen) is derived from the Ancient Greek word πνίγειν (pnígein) meaning "to choke", referring to the choking or stifling property of nitrogen gas.Titanium
Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density, and high strength. Titanium is resistant to corrosion in sea water, aqua regia, and chlorine.
Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and was named by Martin Heinrich Klaproth after the Titans of Greek mythology. The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, water bodies, rocks, and soils. The metal is extracted from its principal mineral ores by the Kroll and Hunter processes. The most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl4), a component of smoke screens and catalysts; and titanium trichloride (TiCl3), which is used as a catalyst in the production of polypropylene.Titanium can be alloyed with iron, aluminium, vanadium, and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial processes (chemicals and petrochemicals, desalination plants, pulp, and paper), automotive, agri-food, medical prostheses, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications.The two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, but less dense. There are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant (73.8%). Although they have the same number of valence electrons and are in the same group in the periodic table, titanium and zirconium differ in many chemical and physical properties.Van Arkel
Van Arkel was a medieval noble family in the County of Holland founded around 1000 near Arkel and lasting until 1412. Their fief was called Land van Arkel.
Other people with this surname include:
Anton Eduard van Arkel (1893-1976), Dutch chemist
Van Arkel process
Van Arkel–Ketelaar triangle
Gerrit van Arkel (1858-1918), Dutch architectVan Arkel–Ketelaar triangle
Bond triangles or van Arkel–Ketelaar triangles (named after Anton Eduard van Arkel and J. A. A. Ketelaar) are triangles used for showing different compounds in varying degrees of ionic, metallic and covalent bonding.Vanadium
Vanadium is a chemical element with symbol V and atomic number 23. It is a hard, silvery-grey, ductile, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) somewhat stabilizes the free metal against further oxidation.
Andrés Manuel del Río discovered compounds of vanadium in 1801 in Mexico by analyzing a new lead-bearing mineral he called "brown lead", and presumed its qualities were due to the presence of a new element, which he named erythronium (derived from Greek for "red") since, upon heating, most of the salts turned red. Four years later, however, he was (erroneously) convinced by other scientists that erythronium was identical to chromium. Chlorides of vanadium were generated in 1830 by Nils Gabriel Sefström who thereby proved that a new element was involved, which he named "vanadium" after the Scandinavian goddess of beauty and fertility, Vanadís (Freyja). Both names were attributed to the wide range of colors found in vanadium compounds. Del Rio's lead mineral was later renamed vanadinite for its vanadium content. In 1867 Henry Enfield Roscoe obtained the pure element.
Vanadium occurs naturally in about 65 minerals and in fossil fuel deposits. It is produced in China and Russia from steel smelter slag; other countries produce it either from magnetite directly, flue dust of heavy oil, or as a byproduct of uranium mining. It is mainly used to produce specialty steel alloys such as high-speed tool steels. The most important industrial vanadium compound, vanadium pentoxide, is used as a catalyst for the production of sulfuric acid. The vanadium redox battery for energy storage may be an important application in the future.
Large amounts of vanadium ions are found in a few organisms, possibly as a toxin. The oxide and some other salts of vanadium have moderate toxicity. Particularly in the ocean, vanadium is used by some life forms as an active center of enzymes, such as the vanadium bromoperoxidase of some ocean algae.Zirconium
Zirconium is a chemical element with symbol Zr and atomic number 40. The name zirconium is taken from the name of the mineral zircon (the word is related to Persian zargun (zircon;zar-gun, "gold-like" or "as gold")), the most important source of zirconium. It is a lustrous, grey-white, strong transition metal that closely resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, respectively. Five isotopes occur naturally, three of which are stable. Zirconium compounds have no known biological role.Zirconium(IV) iodide
Zirconium(IV) iodide is the chemical compound with the formula ZrI4. It is the most readily available iodide of zirconium. It is an orange-coloured solid that degrades in the presence of water.The compound was once prominent as an intermediate in the purification of zirconium metal.