Jan Hendrik de Boer
Encyclopedia
Jan Hendrik de Boer was a Dutch
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

 and chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

.

De Boer was born in Ruinen
Ruinen
Ruinen is a village in the Dutch province of Drenthe. It is located in the municipality of De Wolden, about 10 km northwest of Hoogeveen....

, now De Wolden
De Wolden
- Population centres :Alteveer, Anholt, Ansen, Armweide, Bazuin, Benderse, Berghuizen, Blijdenstein, Bloemberg, Braamberg, Buitenhuizen, Bultinge, De Oude Tol, De Stapel, De Stuw, De Tippe, De Wijk, Dijkhuizen, Dickninge, Drogt, Drogteropslagen, Dunnigen, Echten, Eemten, Engeland, Eursinge, Fort,...

, and died in 's-Gravenzande
's-Gravenzande
s-Gravenzande is a town in the Dutch province of South Holland. It is a part of the municipality of Westland, and lies about 12 km southwest of The Hague. Until 2004 it was a separate municipality and covered an area of 20.77 km² .In 2001, the town of 's-Gravenzande had 15241 inhabitants...

. He studied at the University of Groningen
University of Groningen
The University of Groningen , located in the city of Groningen, was founded in 1614. It is one of the oldest universities in the Netherlands as well as one of its largest. Since its inception more than 100,000 students have graduated...

 and was later employed in industry.

Together with Anton Eduard van Arkel
Anton Eduard van Arkel
Anton Eduard van Arkel, was a Dutch chemist.-See also:*Crystal bar process*Hafnium*Jan Hendrik de Boer*Titanium*Van Arkel-Ketelaar triangle-References:...

, de Boer developed a chemical transport reaction
Chemical transport reaction
In chemistry, a chemical transport reaction describes a process for purification and crystallization of non-volatile solids. The process is also responsible for certain aspects of mineral growth from the effluent of volcanoes. The technique is distinct from chemical vapor deposition, which...

 for titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

, zirconium
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...

, and hafnium
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable...

 known as the crystal bar process
Crystal bar process
The crystal bar 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...

. In a closed vessel the metal reacts with iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

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 + 2I2
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