Aluminium phosphide is an
inorganic compoundInorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
used as a wide
band gapIn solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference between the top of the valence band and the...
semiconductor and a fumigant. This colourless solid is generally sold as a grey-green-yellow powder due to the presence of impurities arising from
hydrolysisHydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
and oxidation.
Properties
AlP crystallizes in the cubic zinc blende lattice, wherein all atoms have tetrahedral coordination. Related materials crystallize similarly, including GaAs. At pressures of 14-17 GPa, AlP transforms into a rocksalt phase .
Aluminium phosphide has a hardness of 5.5 on the
Mohs scaleThe Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...
Aluminium phosphide reacts with
waterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
or acids to release
phosphinePhosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
.
- AlP + 3 H2O → Al(OH)3 + PH3
- AlP + 3 H+ → Al3+ + PH3
Preparation
Crude aluminium phosphide can be prepared in the laboratory by igniting a mixture of red phosphorus and powdered aluminium.
Pesticide
AlP is used as a rodenticide,
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
, and fumigant for stored cereal grains. It is used to kill small verminous
mammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s such as
moleMoles are small cylindrical mammals adapted to a subterranean lifestyle. They have velvety fur; tiny or invisible ears and eyes; and short, powerful limbs with large paws oriented for digging. The term is especially and most properly used for the true moles, those of the Talpidae family in the...
s, and
rodentRodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s. The tablets or pellets typically also contain other chemicals that evolve
ammoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
which helps to reduce the potential for spontaneous
ignitionCombustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...
or
explosionAn explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
of the phosphine gas.
As a rodenticide, aluminium phosphide pellets are provided as a mixture with food for consumption by the rodents. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas. Other pesticides similar to aluminium phosphide are
zinc phosphideZinc phosphide is an inorganic chemical compound.- Reactions :Zinc phosphide can be prepared by the reaction of zinc with phosphorus:Zinc phosphide will react with water to produce phosphine and zinc hydroxide :-Rodenticide:...
and
calcium phosphideCalcium phosphide is a chemical is used in incendiary bombs. It has the appearance of red-brown crystalline powder or grey lumps, with melting point of 1600 °C. Its trade name is Photophor for the incendiary use or Polythanol for the use as rodenticide.It may be formed by reaction of the elements...
.
As a rodenticide, aluminium phosphide can be encountered under various brand names, e.g.
Celphos,
Fumitoxin,
Phostoxin, and
Quick Phos.
Evidently poisonous, aluminium phosphide has been used for suicide. Fumigation has also caused unintentional deaths, such as examples in
Saudi ArabiaThe Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...
and the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Known as "rice tablet" in Iran, for its use to preserve rice, there have been frequent incidents of accidental or intentional death. There is a campaign by Iranian Forensic Medicine Organization to stop its use as a pesticide.
Aluminium phosphide poisoningAcute aluminium phosphide poisoning is a large, though under-reported, problem in the Indian subcontinent. Aluminium phosphide , which is readily available as a fumigant for stored cereal grains, is highly toxic when consumed from a freshly opened container. Death results from profound shock,...
is reported to be highly fatal.
Semiconductor applications
Industrially, AlP is a semiconductor material that is usually
alloyAn alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
ed with other binary materials for applications in devices such as
light-emitting diodeA light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
s (e.g.
aluminium gallium indium phosphideAluminium gallium indium phosphide is a semiconductor material.AlGaInP is used in manufacture of light-emitting diodes of high-brightness red, orange, green, and yellow color, to form the heterostructure emitting light...
).