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Zinc phosphide
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<h2 id="synthesis-and-reactions">Synthesis and reactions</h2> <p>Zinc phosphide can be prepared by the reaction of <a href="/facts/Zinc/80b1qgk3">zinc</a> with <a href="/facts/Phosphorus/27xCeIqs">phosphorus</a>; however, for critical applications, additional processing to remove <a href="/facts/Arsenic/k1c4f44D">arsenic</a> compounds may be needed.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> 6 Zn + P4 → 2 Zn3P2 <p>Another method of preparation include reacting tri-n-octylphosphine with <a href="/facts/Dimethylzinc/FYtqBNxj">dimethylzinc</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p><p>Zinc phosphide reacts with water to produce highly toxic <a href="/facts/Phosphine/aYysn5TS">phosphine</a> (PH3) and <a href="/facts/Zinc_hydroxide/YbPzHlq5">zinc hydroxide</a> (Zn(OH)2): </p> Zn3P2 + 6 H2O → 2 PH3 + 3 Zn(OH)2 <h2 id="structure">Structure</h2> <p>Zn3P2 has a room-temperature <a href="/facts/Tetragonal_crystal_system/12Aop255">tetragonal</a> form that converts to a <a href="/facts/Cubic_crystal_system/92Co7BKM">cubic</a> form at around 845 °C.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> 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.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p><p>The crystalline structure of zinc phosphide is very similar to that of <a href="/facts/Cadmium_arsenide/eLrWjQbQ">cadmium arsenide</a> (Cd3As2), <a href="/facts/Zinc_arsenide/BYwzXy0v">zinc arsenide</a> (Zn3As2) and <a href="/facts/Cadmium_phosphide/U74drJpk">cadmium phosphide</a> (Cd3P2). These compounds of the <a href="/facts/Zinc_cadmium_phosphide_arsenide/2kVqh0Wv">Zn-Cd-P-As quaternary system</a> exhibit full continuous solid-solution.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p> <h2 id="applications">Applications</h2> <h3>Photovoltaics</h3> <p>Zinc phosphide is an ideal candidate for thin film photovoltaic applications, for 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 with that of other thin film <a href="/facts/Photovoltaics/5Xefaayl">photovoltaics</a>. Both zinc and phosphorus are also nontoxic, which is not the case for other common commercial thin film photovoltaics, like <a href="/facts/Cadmium_telluride/eyfWTv6Q">cadmium telluride</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p>Researchers at the <a href="/facts/University_of_Alberta/08ERvE5c">University of Alberta</a> were the first to successfully synthesize colloidal zinc phosphide. Before this, researchers were able to create efficient <a href="/facts/Solar_cell/3L814UCC">solar cells</a> from bulk zinc phosphide, but their fabrication required temperatures greater than 850 °C or complicated vacuum deposition methods. By contrast, colloidal zinc phosphide <a href="/facts/Nanoparticle/k8kNxX4E">nanoparticles</a>, contained in a zinc phosphide “ink”, allows for inexpensive, easy large-scale production, by means of slot-die coating or spray coating.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p><p>The testing and development of these zinc phosphide thin films is still in its early stages, but early results have been positive. Prototype heterojunction devices fabricated from zinc phosphide nanoparticle ink exhibited a rectification ratio of 600 and <a href="/facts/Photosensitivity/dohEzKCm">photosensitivity</a> 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.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p> <h3>Pest control</h3> <h4>Rodenticide</h4> <p>Metal phosphides have been used as <a href="/facts/Rodenticide/unEUuByD">rodenticides</a>. 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 toxic <a href="/facts/Phosphine/aYysn5TS">phosphine</a> 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 <a href="/facts/Aluminium_phosphide/9MvAsh3S">aluminium phosphide</a> and <a href="/facts/Calcium_phosphide/rCnNpWds">calcium phosphide</a>. </p> Zn3P2 + 6H+ → 3Zn++ + PH3 ↑<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> <p>Zinc phosphide is typically added to rodent baits in amount of around 0.75-2%. Such baits have a strong, pungent <a href="/facts/Garlic/NschLR1S">garlic</a>-like odor characteristic of phosphine liberated by <a href="/facts/Hydrolysis/JTvwIHPs">hydrolysis</a>. The odor attracts rodents, but has a repulsive effect on other animals; However, birds, notably <a href="/facts/Wild_turkey/8mffpGov">wild turkeys</a>, 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. </p><p>Rodenticide-grade zinc phosphide usually comes as a black powder containing 75% of zinc phosphide and 25% of <a href="/facts/Potassium_antimony_tartrate/TdraXqak">antimony potassium tartrate</a>, an <a href="/facts/Emetic/R2vQkHqV">emetic</a> 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.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p> <h4>Pest control in New Zealand</h4> <p>The New Zealand <a href="/facts/Environmental_Protection_Authority_(New_Zealand)/mjWGqU5d">Environmental Protection Authority</a> has approved the import and manufacture of Microencapsulated Zinc Phosphide (MZP Paste) for the ground control of <a href="/facts/Common_brushtail_possum/FbGa4muP">possums</a>. The application was made by Pest Tech Limited, with support from Connovation Ltd, <a href="/facts/Lincoln_University_(New_Zealand)/1pYXbcvx">Lincoln University</a> and the <a href="/facts/Animal_Health_Board_(New_Zealand)/fVyxKJHs">Animal Health Board</a>. It will be used as an additional vertebrate poison in certain situations. Unlike <a href="/facts/Sodium_fluoroacetate/6g4RPVmb">1080 poison</a>, it cannot be used for aerial application.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p> <h2 id="safety">Safety</h2> <p>Zinc phosphide is highly toxic, especially when ingested or inhaled. The reason for its toxicity is the release of phosphorus compounds, usually <a href="/facts/Phosphine/aYysn5TS">phosphine</a>, when it reacts with water and acids. Phosphine is very toxic and, with trace amounts of <a href="/facts/Diphosphane/hFQJA6fQ">P2H4</a>, <a href="/facts/Pyrophoric/1b8Sl2AJ">pyrophoric</a>. Phosphine is also denser than air and may remain close to the ground without sufficient <a href="/facts/Ventilation_(architecture)/6p7CVPTj">ventilation</a>. </p> <h2 id="external-links">External links</h2> <ul><li><a href="http://extoxnet.orst.edu/pips/zincphos.htm">Zinc Phosphide Pesticide Information Profile - Extension Toxicology Network</a></li> <li><a href="http://www.epa.gov/pesticides/factsheets/chemicals/rodenticides_fs.htm">EPA Proposed Risk Mitigation Decision for Nine Rodenticides</a></li> <li><i><a href="http://sitem.herts.ac.uk/aeru/ppdb/en/Reports/1730.htm">Zinc phosphide</a></i> in the Pesticide Properties DataBase (PPDB)</li> <li><a href="http://www.michigan.gov/dnr/0,1607,7-153-10370_12150_12220-26326--,00.html">Zinc phosphide properties and use in Michigan</a></li> <li><a href="https://web.archive.org/web/20071008081142/http://milmed.pmk.ac.th/md0173%20PESTICIDES%20IN%20THE%20MILITARY.pdf">MD0173</a> - Pesticides in the military</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Bettermann, G.; Krause, W.; Riess, G.; Hofmann, T. (2002). "Phosphorus Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_527. ISBN 3527306730. <a href="3527306730" target="_blank">3527306730</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Kimball, Gregory M.; Müller, Astrid M.; Lewis, Nathan S.; Atwater, Harry A. (2009). "Photoluminescence-based measurements of the energy gap and diffusion length of Zn[sub 3]P[sub 2]" (PDF). Applied Physics Letters. 95 (11): 112103. Bibcode:2009ApPhL..95k2103K. doi:10.1063/1.3225151. ISSN 0003-6951. <a href="https://authors.library.caltech.edu/16318/1/ApplPhysLett_95_112103.pdf" target="_blank">https://authors.library.caltech.edu/16318/1/ApplPhysLett_95_112103.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Specialist Periodical Reports, Photochemistry, 1981, Royal Society of Chemistry, ISBN 9780851860954 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>F. Wagenknecht and R. Juza "Zinc Phosphides" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1080-1. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Luber, Erik J.; Mobarok, Md Hosnay; Buriak, Jillian M. (2013). "Solution-Processed Zinc Phosphide (α-Zn3P2) Colloidal Semiconducting Nanocrystals for Thin Film Photovoltaic Applications". ACS Nano. 7 (9): 8136–8146. doi:10.1021/nn4034234. ISSN 1936-0851. PMID 23952612. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Evgeniĭ I︠U︡rʹevich Tonkov, 1992, High Pressure Phase Transformations: A Handbook, Vol 2, Gordon and Breach Science Publishers, ISBN 9782881247590 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Trukhan, V. M.; Izotov, A. D.; Shoukavaya, T. V. (2014). "Compounds and solid solutions of the Zn-Cd-P-As system in semiconductor electronics". Inorganic Materials. 50 (9): 868–873. doi:10.1134/S0020168514090143. S2CID 94409384. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Luber, Erik J. (2013). "Solution-Processed Zinc Phosphide (α-Zn 3 P 2 ) Colloidal Semiconducting Nanocrystals for Thin Film Photovoltaic Applications". ACS Nano. 7 (9): 8136–8146. doi:10.1021/nn4034234. PMID 23952612. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"Colloidal zinc phosphide for photovoltaics - nanotechweb.org". Archived from the original on 2013-09-16. <a href="https://web.archive.org/web/20130916163436/http://nanotechweb.org/cws/article/tech/54627" target="_blank">https://web.archive.org/web/20130916163436/http://nanotechweb.org/cws/article/tech/54627</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"Home". <a href="http://www.solarnovus.com/zinc-phosphide-nonocrystals-for-spray-on-solar-thin-films_N7005.html" target="_blank">http://www.solarnovus.com/zinc-phosphide-nonocrystals-for-spray-on-solar-thin-films_N7005.html</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Zinc Phosphide Technical Fact Sheet". npic.orst.edu. <a href="http://npic.orst.edu/factsheets/archive/znptech.html#:~:text=Phospine%20in%20this%20fact%20sheet%20refers%20to%20the%20gaseous%20form%20of%20this%20compound%20The%20chemical%20reaction%20that%20releases%20phosphine%20is11:%20Zn3P2%20+%206H%20%E2%86%92%20PH3%20%E2%86%91%20+%203Zn++" target="_blank">http://npic.orst.edu/factsheets/archive/znptech.html#:~:text=Phospine%20in%20this%20fact%20sheet%20refers%20to%20the%20gaseous%20form%20of%20this%20compound%20The%20chemical%20reaction%20that%20releases%20phosphine%20is11:%20Zn3P2%20+%206H%20%E2%86%92%20PH3%20%E2%86%91%20+%203Zn++</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Why rats can't vomit". Ratbehavior.org. Retrieved 2013-08-17. <a href="http://www.ratbehavior.org/vomit.htm" target="_blank">http://www.ratbehavior.org/vomit.htm</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Environment Risk Management Authority New Zealand. "Zinc phosphide pest poison approved with controls". Retrieved 2011-08-14. <a href="http://www.epa.govt.nz/news/erma-media-releases/Pages/Zinc-phosphide-pest-poison-approved-with-controls-.aspx" target="_blank">http://www.epa.govt.nz/news/erma-media-releases/Pages/Zinc-phosphide-pest-poison-approved-with-controls-.aspx</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> </ol>