Lanthanum phosphide is an

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

lanthanum Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements bet ...

and

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

with the chemical formula LaP.

Synthesis

Lanthanum phosphide can be made by heating lanthanum metal with excess phosphorus in a vacuum: :: 4 La + P₄ → 4 LaP

Physical properties

Lanthanum phosphide forms black crystals of a

cubic system In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of ...

space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

Fmm, cell parameters a = 0.6025 nm, with number of formulas per unit cell Z = 4. The crystals are very unstable and decompose in the open air.

Electronic properties

Lanthanum phosphide is an example of a

strongly correlated material Strongly correlated materials are a wide class of compounds that include insulators and electronic materials, and show unusual (often technologically useful) electronic and magnetic properties, such as metal-insulator transitions, heavy fermi ...

, complicating theoretical prediction of its properties. According to HSE06 calculations, lanthanum phosphide has been theoretically predicted to have an indirect band gap of 0.25 eV along the Γ-X direction. According to HSE06 calculations with spin-orbit coupling, the band gap is predicted to be a direct gap of 0.72 eV at the X point. Using EVGGA, the compound is predicted to have a band gap of 0.56 eV along the Γ-X direction. FP-LAPW has predicted an indirect gap of 0.33 eV along the Γ-X direction.

Chemical properties

Lanthanum phosphide reacts with water, releasing highly toxic

phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...

gas: :: LaP + 3H₂O → La(OH)₃ + PH₃

Uses

Lanthanum phosphide compound is a

semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

used in high power, high frequency applications, and in

laser diode file:Laser diode chip.jpg, The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD or semiconductor laser or diode laser) is a semiconductor device similar to a light-emittin ...

Lanthanum polyphosphide

In addition to the simple phosphide, LaP, lanthanum and phosphorus can also form phosphorus-rich compounds such as LaP₂ LaP₅ and LaP₇.