Aluminum phosphide is a highly toxic inorganic compound with the chemical formula AlP , a wide band gap semiconductor and used as a fumigant . This colorless solid is usually sold as a gray-greenish-yellow powder due to the presence of impurities resulting from hydrolysis and oxidation .
|chemical formula||al pu|
|molar mass||57.9552 g/mol|
|appearance||yellow or brown crystals|
|density||2.85 g/ cm3|
|Melting point||2,530 °C (4,590 °F; 2,800 K)|
|Solubility in water||feedback|
|band gap||2.5 eV (indirect)|
|refractive index ( nd )||2.75 (IR), ~3 (Vis)|
AlP crystals are dark brown to dark yellow in color and have a zincblende crystal structure with a lattice constant of 5.4510 at 300 K.  They are thermodynamically stable up to 1,000 °C (1,830 °F).
Aluminum phosphide reacts with water or acid to release phosphine:
Alp + 3H 2 O → Al(OH) 3 + pH 3
Alp + 3H + → Al 3+ + pH 3
AlP is synthesized by combining elements:
4Al + P 4 → 4AlP
Care must be taken to avoid exposure of AlP to any source of moisture, as this generates toxic phosphine gas.
ALP is used as a rodenticide, insecticide, and fumigant for stored grain. It is used to kill small insectivorous mammals such as moles and rodents. The tablets or pellets, known as “wheat pellets”, usually also contain other chemicals that develop ammonia which helps reduce the chances of spontaneous ignition or explosion of phosphine gas.
AlP is used as both a fumigant and an oral insecticide. As a rodenticide, aluminum phosphide pellets are provided as a mixture with food for consumption by rodents. The acid in the rodent’s digestive tract reacts with phosphide to produce toxic phosphine gas. Other insecticides similar to aluminum phosphide are zinc phosphide and calcium phosphide. In this application, aluminum phosphide may be encountered under various brand names, such as Quickphos , Celphos , Fostox , Fumitoxin , Phostek , Phostoxin , Talunex , Fieldphos , and Mite-Cide., It generates phosphine gas according to the following hydrolysis equation.
2 Alp + 6 H 2 O → Al 2 O 3 3 H 2 O + 2 PH 3
It is used as a fumigant when other insecticide applications are impractical and when treating structures and installations, such as in ships, aircraft and grain silos. All of these structures can be effectively sealed or enclosed in a gastite membrane, allowing the phosphine fumes to be contained and concentrated. Fumigants are also applied directly to rodent bills. 
Industrially, ALP is a semiconductor material commonly mixed with other binary materials for applications in devices such as light-emitting diodes (such as aluminum gallium indium phosphide).
Highly toxic, aluminum phosphide has been used for suicide.  There have also been unintentional deaths from fumigation.    There have been frequent incidents of accidental or intentional death, for its use to preserve rice, known in Iran as “rice pellet”. A campaign is being run by the Iranian Forensic Medicine Organization to stop its use as a pesticide.
Recycling of used aluminum phosphide containers caused death of three family members in Alcalá de Guadaíra, Spain. They were stuffing them in plastic sacks in their bathroom. Accidental deaths were caused by aluminum phosphide reacting with water or moisture and forming phosphine, causing their death within hours. Aluminum phosphide poisoning is considered a widespread problem in the Indian subcontinent.