Editing Phosphorus (section)

==Applications==
{{About|the applications of elemental phosphorus|the applications of phosphorus compounds|Phosphorus#Compounds|section=yes}}

===Matches===
{{main|Match}}
[[File:Match striking surface.jpg|thumb|Match striking surface made of a mixture of red phosphorus, glue and ground glass. The glass powder is used to increase the friction.]]
Safety matches are very difficult to ignite on any surface other than a special striker strip. The strip contains non-toxic red phosphorus and the match head [[potassium chlorate]], an oxygen-releasing compound. When struck, small amounts of [[Abrasion (mechanical)|abrasion]] from match head and striker strip are mixed intimately to make a small quantity of [[Armstrong's mixture]], a very touch sensitive composition. The fine powder ignites immediately and provides the initial spark to set off the match head. Safety matches separate the two components of the ignition mixture until the match is struck. This is the key safety advantage as it prevents accidental ignition.{{r|Wiberg2001|Hardt2001}}

===Military===
Though military uses of white phosphorus are constrained by modern international law, [[white phosphorus munition]]s are still used for military applications, such as [[incendiary device|incendiary bombs]], [[smoke screen]]s, [[smoke bomb]]s, and [[tracer ammunition]].

===Drug production===
Elemental phosphorus can reduce elemental [[iodine]] to [[hydroiodic acid]], which is a reagent effective for reducing [[ephedrine]] or [[pseudoephedrine]] to [[methamphetamine]].{{r|Skinner1990}} For this reason, red and white phosphorus are listed in the United States as [[DEA list of chemicals#List I chemicals|List I precursor chemicals]] by the [[Drug Enforcement Administration]], and their handling is subject to stringent regulatory controls.{{r|CFR1|CFR2|CSA}}

===Metallurgical aspects===
Phosphorus is also an important component in [[steel]] production, in the making of [[phosphor bronze]], and in many other related products.{{r|Scholz2014|Schwartz2016}} Phosphorus is added to metallic copper during its smelting process to react with oxygen present as an impurity in copper and to produce phosphorus-containing copper ([[CuOFP]]) alloys with a higher [[hydrogen embrittlement]] resistance than normal copper.{{r|Davisz2001}} [[Phosphate conversion coating]] is a chemical treatment applied to steel parts to improve their corrosion resistance.

===Semiconductors===
Phosphorus is a [[doping (semiconductor)|dopant]] in [[Extrinsic semiconductor#N-type semiconductors|N-type semiconductor]]s used in high-power electronics and [[semiconductor detector]]s.{{r|MIT}} In this context, phosphorus is not present at the start of the process, but rather created directly out of silicon during the manufacture of the devices. This is done by neutron [[nuclear transmutation|transmutation]] doping, a method based on the conversion of the [[Isotopes_of_silicon|{{chem2|^{30}Si}}]] into {{chem2|^{31}P}} by [[neutron capture]] and [[beta decay]] as follows:
<math chem display="block">^{30}\mathrm{Si} \, (n,\gamma) \, ^{31}\mathrm{Si} \rightarrow \, ^{31}\mathrm{P} + \beta^- \; (T_{1/2} = 2.62 \mathrm{h})</math>

In practice, the silicon is typically placed near or inside a [[nuclear reactor]] generating neutrons. As neutrons pass through the silicon, phosphorus atoms are produced by transmutation. This doping method is far less common than diffusion or ion implantation, but it has the advantage of creating an extremely uniform dopant distribution.{{r|Baliga1987|Schmidt1998}}