Listing description
·
Linear Formula Zn3P2
·
Molecular Weight 258.12
Zinc phosphide (Zn3P2) is an inorganic chemical
compound. It is
a grey solid, although commercial samples are often dark or even black. It is
used as a rodenticide.[2] Zn3P2 is
a semiconductor with a direct band gap of 1.5 eV.[3] and may have applications in photovoltaic
cells.[4] A second zinc phosphide is known, with the stoichiometry ZnP2.
Detailed description
Synthesis and reactions
Zinc phosphide can be prepared by the reaction of
zinc with phosphorus; however, for critical applications, additional processing
to remove arsenic compounds may be needed.[5]
3
Zn + 2 P → Zn3P2
Zn3P2 + 6 H2O → 2 PH3 + 3 Zn(OH)2
Structure
Zn3P2 has two forms, a room temperature tetragonal form which converts
to a cubic form at around
845 °C.[7] In the room
temperature form there are discrete P atoms, zinc atoms are tetrahedrally
coordinated and phosphorus six coordinate, with zinc atoms at 6 of the vertices
of a distorted cube.[8] ZnP2 has two forms a lower temperature red tetragonal form and a black monoclinic form.[7] In both of these there
are chains of P atoms, helical in the tetragonal, semi-spiral in the
monoclinic.[9]
Thin Film Photovoltaic Applications[edit]
Zinc Phosphide is an ideal candidate for thin film
photovoltaic applications, since it has strong optical absorption and an almost
ideal band gap (1.5eV). In addition to this, both zinc and phosphorus are found
abundantly in the earth’s crust, meaning that material extraction cost is low
compared to other thin film photovoltaics. Both zinc and phosphorus are also
nontoxic, which is not the case for other common commercial thin film
photovoltaics, like Cadmium Telluride. [10]
Researchers at the University of Alberta have
successfully synthesized colloidal zinc phosphide, and are the first to do so.
Before, researchers were able to create efficient solar cells from bulk zinc
phosphide, but their fabrication required temperatures greater than 850 C or
complicated vacuum deposition methods. By contrast, colloidal zinc phosphide
nanoparticles, contained in a zinc phosphide “ink”, allows for inexpensive,
easy large-scale production, by means of slot-die coating or spray coating. [11]
The testing and development of these zinc phosphide
thin films is still in its early stages, but early results are positive.
Prototype heterojunction devices fabricated from zinc phosphide nanoparticle
ink exhibited a rectification ratio of 600 and photosensitivity with an on/off
ratio near 100. These are both acceptable suitability benchmarks for solar
cells. Development still needs to be made on optimizing the nanoparticle ink
formation and device architecture before commercialization is possible, but
commercial spray-on zinc phosphide solar cells may be possible within ten
years. [12]
Rodenticide
Metal phosphides have been used as rodenticides. A mixture of food
and zinc phosphide is left where the rodents can eat it. The acid in the
digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas. This method of
vermin control has possible use in places where rodents are immune to other
common poisons. Other pesticides similar to zinc phosphide are aluminium phosphide and calcium phosphide.
Zinc phosphide is typically added to rodent baits in
amount of around 0.75-2%. Such baits have strong, pungent garlic-like odor
characteristic for phosphine liberated by hydrolysis. The odor attracts
rodents, but has a repulsive effect on other animals; However, birds, notably wild turkeys, are not sensitive
to the smell. The baits have to contain sufficient amount of zinc phosphide in
sufficiently attractive food in order to kill rodents in a single serving; a
sublethal dose may cause aversion towards zinc-phosphide baits encountered by
surviving rodents in the future.
Rodenticide-grade zinc phosphide usually comes as a
black powder containing 75% of zinc phosphide and 25% of antimony potassium
tartrate, an emetic to cause vomiting if
the material is accidentally ingested by humans or domestic animals. However,
it is still effective against rats, mice, guinea pigs and rabbits, none of
which have a vomiting reflex.[13]
Zinc phosphide use in New Zealand
The New Zealand Environmental Protection Authority has approved the
import and manufacture of Microencapsulated Zinc Phosphide (MZP Paste) for the
ground control of possums. The application
was made by Pest Tech Limited, with support from Connovation Ltd, Lincoln University and the Animal Health Board. It will be used as an additional vertebrate poison in certain
situations. Unlike 1080 poison, it cannot be used
for aerial application.
Safety
Zinc phosphide is highly toxic. In Indian
certification markings, it is marked as 'Highly Dangerous', which means that
1-50 mg of the substance ingested orally can be lethal.
PRICE
$140.09/KG OR $63.67/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
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