# Chemicals/Phosphoruses

Phosphorus has several allotropes that exhibit strikingly diverse properties. The two most common allotropes are white phosphorus and red phosphorus.

## Visuals

"The P species in the titania lattice should be the dominant group responsive to visible light, whereas the P species on the surface could retard the phase transition of anatase to rutile and increase the surface area and adsorption capability."
"The P species in the titania lattice should be the dominant group responsive to the visible light activity, although P species on the surface could retard the phase transition of anatase to rutile, and increase the surface area and adsorption capability, consequently enhancing the photocatalytic activity."

## White phosphoruses

From the perspective of applications and chemical literature, the most important form of elemental phosphorus is white phosphorus, often abbreviated as WP, is a soft, waxy solid which consists of tetrahedral P $_4$ molecules, in which each atom is bound to the other three atoms by a formal single bond, this P $_4$ tetrahedron is also present in liquid and gaseous phosphorus up to the temperature of 800 °C (1,470 °F) when it starts decomposing to P $_2$ molecules. The P $_4$ molecule in the gas phase has a P-P bond length of r$_g$ = 2.1994(3) Å as was determined by gas electron diffraction. The nature of bonding in this P $_4$ tetrahedron can be described by spherical aromaticity or cluster bonding, that is the electrons are highly delocalized. This has been illustrated by calculations of the magnetically induced currents, which sum up to 29 nA/T, much more than in the archetypical aromatic molecule benzene (11 nA/T).
White phosphorus exists in two crystalline forms: α (alpha) and β (beta): at room temperature, the α-form is stable, more common, has cubic crystal structure and at 195.2 K (−78.0 °C), transforms into β-form.
The β-form has hexagonal crystal structure and differ in terms of the relative orientations of the constituent P$_4$ tetrahedra. The β form of white phosphorus contains three slightly different P $_4$ molecules, i.e. 18 different P-P bond lengths between 2.1768(5) and 2.1920(5) Å, with the average P-P bond length is 2.183(5) Å.
White phosphorus is the least stable, the most reactive, the most volatile, the least dense and the most toxic of the allotropes which gradually changes to red phosphorus, transformation is accelerated by light and heat, and samples of white phosphorus almost always contain some red phosphorus and accordingly appear yellow.
For this reason, white phosphorus that is aged or otherwise impure (e.g., weapons-grade, not lab-grade WP) is also called yellow phosphorus, when exposed to oxygen, white phosphorus glows in the dark with a very faint tinge of green and blue, is highly flammable and pyrophoric (self-igniting) upon contact with air, has a characteristic garlic smell, and samples are commonly coated with white "phosphorus pentoxide", which consists of P $_4$O $_{10}$ tetrahedra with oxygen inserted between the phosphorus atoms and at their vertices, is insoluble in water but soluble in carbon disulfide.

## Black phosphoruses

Black phosphorus is the thermodynamically stable form of phosphorus at room temperature and pressure, with a standard enthalpy of formation (heat of formation) of -39.3 kJ/mol (relative to white phosphorus which is defined as the standard state).
As a 2D material, in appearance, properties, and structure, black phosphorus is very much like graphite with both being black and flaky, a conductor of electricity, and having puckered sheets of linked atoms.
Black phosphorus has an orthorhombic pleated honeycomb structure and is the least reactive allotrope, a result of its lattice of interlinked six-membered rings where each atom is bonded to three other atoms. In this structure, each phosphorous atom has 5 outer shell electrons. Black and red phosphorus can also take a cubic crystal lattice structure. The first high-pressure synthesis of black phosphorus crystals was made in 1914. Metal salts catalyze the synthesis of black phosphorus.

## Violets

Violet phosphorus is a form of phosphorus that can be produced by day-long annealing of red phosphorus above 550 °C, when phosphorus was recrystallised from molten lead, a red/purple form is obtained, sometimes known as "Hittorf's phosphorus" (or violet or α-metallic phosphorus).

## Blues

Single-layer blue phosphorus was first produced by the method of molecular beam epitaxy from black phosphorus as precursor.

## Yellows

White phosphorus is a translucent waxy solid that quickly becomes yellow when exposed to light.

## Reds

Under standard conditions red phosphorus is more stable than white phosphorus, but less stable than the thermodynamically stable black phosphorus, with a standard enthalpy of formation of red phosphorus is -17.6 kJ/mol.
P$_{12}$ nanorod polymers were isolated from CuI-P complexes using low temperature treatment.
Electron microscopy showed that red/brown phosphorus forms long, parallel nanorods with a diameter between 3.4 Å and 4.7 Å.

## Gases

Gaseous phosphorus exists as diphosphorus and atomic phosphorus.
The diphosphorus allotrope (P$_2$) can normally be obtained only under extreme conditions (for example, from P$_4$ at 1100 kelvin): the diatomic molecule was generated in homogeneous solution under normal conditions with the use of transition metal complexes (for example, tungsten and niobium).

## Liquids

The P $_4$ tetrahedron is present in liquid phosphorus.

## Solids

White phosphorus is a soft, waxy solid which consists of tetrahedral P $_4$ molecules.
Properties of some allotropes of phosphorus :
| Form | white(α) | white(β) | violet | black |
| Symmetry | Body-centred cubic | Triclinic | Monoclinic | Orthorhombic |
| Pearson symbol | | aP24 | mP84 | oS8 |
| Space group | I43m | P1 No.2 | P2/c No.13 | Cmca No.64 |
| Density (g/cm$^3$) | 1.828 | 1.88 | 2.36 | 2.69 |
| Bandgap (eV) | 2.1 | | 1.5 | 0.34 |
| Refractive index | 1.8244 | | 2.6 | 2.4 |

## Alloys

Phosphorus is an important component in steel production, in the making of phosphor bronze, and in many other related products.
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.

## Minerals

Phosphate minerals contain the tetrahedrally coordinated phosphate (PO$_4$$^{3−}$) anion along sometimes with arsenate (AsO$_4$$^{3−}$) and vanadate (VO$_4$$^{3−}$) substitutions, and chloride (Cl$^−$), fluoride (F$^−$), and hydroxide (OH$^−$) anions that also fit into the crystal structure.

## Allabogdanites

Allabogdanite is a very rare phosphide mineral with formula (Fe,Ni) $_2$P, found in 1994 in the Onello meteorite. It was described for an occurrence in the Onello meteorite in the Onello River basin, Sakha Republic; Yakutia, Russia; associated with taenite, schreibersite, kamacite, graphite and awaruite. It was named for Russian geologist Alla Bogdanova.
In June 2021 terrestrial allabogdanite was discovered in a sedimentary formation, located in the Negev desert of Israel, just southwest of the Dead Sea.

## Iron–Nickel–Chromium–Cobalt–Phosphorus

"Grain size varies from 98 to 530 lm with an average of *150 lm. Minor [elements] oxidation [from an iron–nickel–chromium–cobalt–phosphorus alloy] is evidenced by the presence of a light brown and blue surface layer composed of very fine-grained (<1 lm) crystals on the surface." "[T]he oxidation of minor elements in metallic alloys in the early solar system" is indicated to possess at instances a blue surface layer.

## Schreibersites

Schreibersite is generally a rare iron nickel phosphide mineral, (Fe,Ni)$_3$P, though common in iron-nickel meteorites, where the only known occurrence of the mineral on Earth is located on Disko Island in Greenland.
Another name used for the mineral is rhabdite that forms tetragonal crystals with perfect 001 cleavage; color ranges from bronze to brass yellow to silver white; density is 7.5 and a hardness of 6.5 – 7; opaque with a metallic luster and a dark gray streak; named after the Austrian scientist Carl Franz Anton Ritter von Schreibers (1775–1852), who was one of the first to describe it from iron meteorites.
Schreibersite is reported from the Magura Meteorite, Arva-(present name – Orava), Slovak Republic; the Sikhote-Alin Meteorite in eastern Russia; the São Julião de Moreira Meteorite, Viana do Castelo, Portugal; the Gebel Kamil (meteorite) in Egypt; and numerous other locations including the Moon.
Schreibersite and other meteoric phosphorus bearing minerals may be the ultimate source for the phosphorus that is so important for life on Earth. Pyrophosphite is a possible precursor to pyrophosphate, the molecule associated with adenosine triphosphate (ATP), a co-enzyme central to energy metabolism in all life on Earth, produced by subjecting a sample of schreibersite to a warm, acidic environment typically found in association with volcanic activity, activity that was far more common on the primordial Earth, possibly representing "chemical life", a stage of evolution which may have led to the emergence of fully biological life as exists today.

## Phosphorites

The Phosphoria Formation is the most famous phosphorite unit in America. On a global scale, phosphorite deposition was at its maximum, volumetrically, during the Neoproterozoic and Cambrian (see Zhongyicun Member phosphorite specimen).
The fossiliferous peloidal phosphorite comes from just south of Ercaicun, ~4 km WSW of Haikou, Kunming City Prefecture, east-central Yunnan Province, southwestern China. This rock was deposited not long after the Cambrian Explosion (the sudden, evolutionary appearance of abundant fossil life near the Precambrian-Cambrian boundary).
On a global scale, phosphorite deposition was at its maximum, volumetrically, during the Neoproterozoic and Cambrian.

## Glaciology

"Phosphorus has been shown to be deficient in glacial environments, and thus is one of the limits on microbial growth and activity."

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