Lanthanum phosphide is an inorganic compound of lanthanum and phosphorus with the chemical formula LaP.
Synthesis Lanthanum phosphide can be made by heating lanthanum metal with excess phosphorus in a vacuum: Google books Journal index
4 La + P4 → 4 LaP
Physical properties Lanthanum phosphide forms black crystals of a cubic system, space group 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, 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 gas:
LaP + 3H2O → La(OH)3 + PH3
Uses Lanthanum phosphide is a semiconductor used in high power, high frequency applications, and in laser diodes.
Lanthanum polyphosphide In addition to the simple phosphide, LaP, lanthanum and phosphorus can also form phosphorus-rich compounds such as LaP2 LaP5 and LaP7.
References
Further reading HathiTrust (no access)