Magnesium oxide: Difference between revisions

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| BoilingPt_ref=<ref name="CRCPress-2011a"/>
| BoilingPt_ref=<ref name="CRCPress-2011a"/>
| Solubility =  
| Solubility =  
| SolubleOther = Soluble in [[acid]], [[ammonia]] <br> insoluble in [[ethanol|alcohol]]
| SolubleOther = Soluble in [[acid]] ([[Chemical reaction|reacts]] to form usually [[Solubility|soluble]] [[Salt (chemistry)|salts]], e.g. [[Magnesium chloride|MgCl<sub>2</sub>]] in [[hydrochloric acid|HCl]]), [[ammonia]] <br /> insoluble in [[ethanol|alcohol]]
| ThermalConductivity = 45–60&nbsp;W·m<sup>−1</sup>·K<sup>−1</sup><ref>[http://www.konoshima.co.jp/en/resdev/004.html Application of magnesium compounds to insulating heat-conductive fillers] {{webarchive|url=https://web.archive.org/web/20131230233440/http://www.konoshima.co.jp/en/resdev/004.html |date=2013-12-30 }}. konoshima.co.jp</ref>
| ThermalConductivity = 45–60&nbsp;W·m<sup>−1</sup>·K<sup>−1</sup><ref>[http://www.konoshima.co.jp/en/resdev/004.html Application of magnesium compounds to insulating heat-conductive fillers] {{webarchive|url=https://web.archive.org/web/20131230233440/http://www.konoshima.co.jp/en/resdev/004.html |date=2013-12-30 }}. konoshima.co.jp</ref>
| RefractIndex = 1.7355
| RefractIndex = 1.7355
| BandGap = 7.8 eV<ref>{{cite journal |journal=Solid State Communications |volume=55 |year=1985 |pages=351–5 |title=Self-consistent electronic structures of MgO and SrO |first1=O.E. |last1=Taurian |doi=10.1016/0038-1098(85)90622-2 |last2=Springborg |first2=M. |last3=Christensen |first3=N.E. |issue=4 |url=http://users-phys.au.dk/nec/Papers/necSSC/SSC55351.pdf |bibcode=1985SSCom..55..351T |access-date=2012-03-27 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303213012/http://users-phys.au.dk/nec/Papers/necSSC/SSC55351.pdf |url-status=dead }}</ref>
| BandGap = 7.8 eV<ref>{{cite journal |journal=Solid State Communications |volume=55 |year=1985 |pages=351–5 |title=Self-consistent electronic structures of MgO and SrO |first1=O.E. |last1=Taurian |doi=10.1016/0038-1098(85)90622-2 |last2=Springborg |first2=M. |last3=Christensen |first3=N.E. |issue=4 |url=http://users-phys.au.dk/nec/Papers/necSSC/SSC55351.pdf |bibcode=1985SSCom..55..351T |access-date=2012-03-27 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303213012/http://users-phys.au.dk/nec/Papers/necSSC/SSC55351.pdf }}</ref>
| Dipole = 6.2 ± 0.6 D
| Dipole = 6.2 ± 0.6 D
| MagSus = −10.2·10<sup>−6</sup> cm<sup>3</sup>/mol<ref>{{RubberBible92nd|page=4.133}}</ref>
| MagSus = −10.2·10<sup>−6</sup> cm<sup>3</sup>/mol<ref>{{RubberBible92nd|page=4.133}}</ref>
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  }}
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'''Magnesium oxide''' ('''MgO'''), or '''magnesia''', is a white [[hygroscopy|hygroscopic]] solid [[mineral]] that occurs naturally as [[periclase]] and is a source of [[magnesium]] (see also [[oxide]]). It has an [[empirical formula]] of MgO and consists of a [[crystal structure|lattice]] of Mg<sup>2+</sup> ions and O<sup>2−</sup> ions held together by [[ionic bond]]ing. [[Magnesium hydroxide]] forms in the presence of water (MgO + H<sub>2</sub>O → Mg(OH)<sub>2</sub>), but it can be reversed by heating it to remove moisture.
'''Magnesium oxide''' ('''MgO'''), or '''magnesia''', is a white [[hygroscopy|hygroscopic]] solid [[mineral]] that occurs naturally as [[periclase]] and is a source of [[magnesium]] (see also [[oxide]]). It has an [[empirical formula]] of MgO and consists of a [[crystal structure|lattice]] of Mg<sup>2+</sup> ions and O<sup>2−</sup> ions held together by [[ionic bond]]ing. [[Magnesium hydroxide]] forms in the presence of [[water]] (MgO + H<sub>2</sub>O → Mg(OH)<sub>2</sub>), but it can be reversed by heating it to remove moisture.


Magnesium oxide was historically known as '''magnesia alba''' (literally, the white mineral from [[Ancient Magnesia|Magnesia]]), to differentiate it from ''[[magnesia nigra]]'', a black mineral containing what is now known as [[manganese]].
Magnesium oxide was historically known as '''magnesia alba''' (literally, the white mineral from [[Ancient Magnesia|Magnesia]]), to differentiate it from ''[[magnesia nigra]]'', a black mineral containing what is now known as [[manganese]].


==Related oxides==
==Related oxides==
While "magnesium oxide" normally refers to MgO, the compound [[magnesium peroxide]] MgO<sub>2</sub> is also known. According to evolutionary crystal structure prediction,<ref>{{cite journal| last = Zhu| first = Qiang| author2 = Oganov A.R.| author3 = Lyakhov A.O.| title = Novel stable compounds in the Mg-O system under high pressure| journal = Phys. Chem. Chem. Phys.| year = 2013| volume = 15| issue = 20| pages = 7696–7700| url = http://uspex.stonybrook.edu/pdfs/Mg-O-paper-2013.pdf| doi = 10.1039/c3cp50678a| pmid = 23595296| bibcode = 2013PCCP...15.7696Z| access-date = 2013-11-06| archive-date = 2013-12-03| archive-url = https://web.archive.org/web/20131203011451/http://uspex.stonybrook.edu/pdfs/Mg-O-paper-2013.pdf| url-status = dead}}</ref> MgO<sub>2</sub> is thermodynamically stable at pressures above 116 GPa (gigapascals), and a semiconducting [[suboxide]] Mg<sub>3</sub>O<sub>2</sub> is thermodynamically stable above 500 GPa. Because of its stability, MgO is used as a model system for investigating vibrational properties of crystals.<ref>{{cite journal| last= Mei| first = AB|author2=O. Hellman|author3=C. M. Schlepütz|author4= A. Rockett|author5= T.-C. Chiang|author6= L. Hultman|author7= I. Petrov|author-link7=Ivan Georgiev Petrov|author8= J. E. Greene|author-link8=J. E. Greene|title= Reflection Thermal Diffuse X-Ray Scattering for Quantitative Determination of Phonon Dispersion Relations.|journal=Physical Review B|volume= 92| issue = 17|year= 2015|page=174301| doi=10.1103/physrevb.92.174301|bibcode=2015PhRvB..92q4301M|doi-access= free}}</ref>
While "magnesium oxide" normally refers to MgO, the compound [[magnesium peroxide]] MgO<sub>2</sub> is also known. According to evolutionary crystal structure prediction,<ref>{{cite journal| last = Zhu| first = Qiang| author2 = Oganov A.R.| author3 = Lyakhov A.O.| title = Novel stable compounds in the Mg-O system under high pressure| journal = Phys. Chem. Chem. Phys.| year = 2013| volume = 15| issue = 20| pages = 7696–7700| url = http://uspex.stonybrook.edu/pdfs/Mg-O-paper-2013.pdf| doi = 10.1039/c3cp50678a| pmid = 23595296| bibcode = 2013PCCP...15.7696Z| access-date = 2013-11-06| archive-date = 2013-12-03| archive-url = https://web.archive.org/web/20131203011451/http://uspex.stonybrook.edu/pdfs/Mg-O-paper-2013.pdf}}</ref> MgO<sub>2</sub> is thermodynamically stable at pressures above 116 GPa (gigapascals), and a semiconducting [[suboxide]] Mg<sub>3</sub>O<sub>2</sub> is thermodynamically stable above 500 GPa. Because of its stability, MgO is used as a model system for investigating vibrational properties of crystals.<ref>{{cite journal| last= Mei| first = AB|author2=O. Hellman|author3=C. M. Schlepütz|author4= A. Rockett|author5= T.-C. Chiang|author6= L. Hultman|author7= I. Petrov|author-link7=Ivan Georgiev Petrov|author8= J. E. Greene|author-link8=J. E. Greene|title= Reflection Thermal Diffuse X-Ray Scattering for Quantitative Determination of Phonon Dispersion Relations.|journal=Physical Review B|volume= 92| issue = 17|year= 2015|article-number=174301| doi=10.1103/physrevb.92.174301|bibcode=2015PhRvB..92q4301M|doi-access= free}}</ref>


== Electric properties ==
== Electric properties ==
Pure MgO is not conductive and has a high resistance to electric current at [[room temperature]]. The pure powder of MgO has a [[relative permittivity]] inbetween 3.2 to 9.9 <math>k</math> with an approximate [[dielectric loss]] of [[Dissipation factor|tan(δ)]] > 2.16x10<sup>3</sup> at 1kHz.<ref name="Johnson-1986">{{Cite thesis |last=A P |first=Johnson |date=November 1986 |title=Structural and electrical properties of magnesium oxide powders |url=http://etheses.dur.ac.uk/7037/ |publisher=Durham University|type=Masters }}</ref><ref name="Subramanian-1989">{{Cite journal |last1=Subramanian |first1=M. A. |last2=Shannon |first2=R. D. |last3=Chai |first3=B. H. T. |last4=Abraham |first4=M. M. |last5=Wintersgill |first5=M. C. |date=November 1989 |title=Dielectric constants of BeO, MgO, and CaO using the two-terminal method |url=http://link.springer.com/10.1007/BF00209695 |journal=Physics and Chemistry of Minerals |language=en |volume=16 |issue=8 |pages=741–746 |doi=10.1007/BF00209695 |bibcode=1989PCM....16..741S |s2cid=95280958 |issn=0342-1791}}</ref><ref name="Hornak-2018">{{Cite journal |last1=Hornak |first1=Jaroslav |last2=Trnka |first2=Pavel |last3=Kadlec |first3=Petr |last4=Michal |first4=Ondřej |last5=Mentlík |first5=Václav |last6=Šutta |first6=Pavol |last7=Csányi |first7=Gergely |last8=Tamus |first8=Zoltán |date=2018-05-30 |title=Magnesium Oxide Nanoparticles: Dielectric Properties, Surface Functionalization and Improvement of Epoxy-Based Composites Insulating Properties |journal=Nanomaterials |language=en |volume=8 |issue=6 |pages=381 |doi=10.3390/nano8060381 |issn=2079-4991 |pmc=6027305 |pmid=29848967|doi-access=free }}</ref>
Pure MgO is not conductive and has a high resistance to electric current at [[room temperature]]. The pure powder of MgO has a [[relative permittivity]] inbetween 3.2 to 9.9 <math>k</math> with an approximate [[dielectric loss]] of [[Dissipation factor|tan(δ)]] > 2.16x10<sup>3</sup> at 1kHz.<ref name="Johnson-1986">{{Cite thesis |last=A P |first=Johnson |date=November 1986 |title=Structural and electrical properties of magnesium oxide powders |url=http://etheses.dur.ac.uk/7037/ |publisher=Durham University|type=Masters }}</ref><ref name="Subramanian-1989">{{Cite journal |last1=Subramanian |first1=M. A. |last2=Shannon |first2=R. D. |last3=Chai |first3=B. H. T. |last4=Abraham |first4=M. M. |last5=Wintersgill |first5=M. C. |date=November 1989 |title=Dielectric constants of BeO, MgO, and CaO using the two-terminal method |url=http://link.springer.com/10.1007/BF00209695 |journal=Physics and Chemistry of Minerals |language=en |volume=16 |issue=8 |pages=741–746 |doi=10.1007/BF00209695 |bibcode=1989PCM....16..741S |s2cid=95280958 |issn=0342-1791|url-access=subscription }}</ref><ref name="Hornak-2018">{{Cite journal |last1=Hornak |first1=Jaroslav |last2=Trnka |first2=Pavel |last3=Kadlec |first3=Petr |last4=Michal |first4=Ondřej |last5=Mentlík |first5=Václav |last6=Šutta |first6=Pavol |last7=Csányi |first7=Gergely |last8=Tamus |first8=Zoltán |date=2018-05-30 |title=Magnesium Oxide Nanoparticles: Dielectric Properties, Surface Functionalization and Improvement of Epoxy-Based Composites Insulating Properties |journal=Nanomaterials |language=en |volume=8 |issue=6 |page=381 |doi=10.3390/nano8060381 |issn=2079-4991 |pmc=6027305 |pmid=29848967|doi-access=free }}</ref>


==Production==
==Production==
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===Biomedical===
===Biomedical===
Among metal oxide nanoparticles, magnesium oxide nanoparticles (MgO NPs) have distinct physicochemical and biological properties, including biocompatibility, biodegradability, high bioactivity, significant antibacterial properties, and good mechanical properties, which make it a good choice as a reinforcement in composites.<ref>{{cite journal |vauthors=Saberi A, Baltatu MS, Vizureanu P |title=Recent Advances in Magnesium-Magnesium Oxide Nanoparticle Composites for Biomedical Applications |journal=Bioengineering |volume=11 |issue=5 |pages=508 |date=May 2024 |pmid=38790374 |pmc=11117911 |doi=10.3390/bioengineering11050508 |doi-access=free}}</ref>
Among metal oxide [[Nanoparticle|nanoparticles]], magnesium oxide nanoparticles (MgO NPs) have distinct physicochemical and biological properties, including biocompatibility, biodegradability, high bioactivity, significant antibacterial properties, and good mechanical properties, which make it a good choice as a reinforcement in composites.<ref>{{cite journal |vauthors=Saberi A, Baltatu MS, Vizureanu P |title=Recent Advances in Magnesium-Magnesium Oxide Nanoparticle Composites for Biomedical Applications |journal=Bioengineering |volume=11 |issue=5 |page=508 |date=May 2024 |pmid=38790374 |pmc=11117911 |doi=10.3390/bioengineering11050508 |doi-access=free}}</ref>


====Heating elements====
====Heating elements====
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===Medical===
===Medical===
Magnesium oxide is used for relief of heartburn and indigestion, as an [[antacid]], magnesium supplement, and as a short-term [[laxative]]. It is also used to improve symptoms of [[indigestion]]. Side effects of magnesium oxide may include nausea and cramping.<ref>[https://www.nlm.nih.gov/medlineplus/druginfo/meds/a601074.html Magnesium Oxide]. MedlinePlus. Last reviewed 02/01/2009</ref> In quantities sufficient to obtain a laxative effect, side effects of long-term use may rarely cause [[enterolith]]s to form, resulting in [[bowel obstruction]].<ref>{{cite journal| author = Tatekawa Y| title = Small bowel obstruction caused by a medication bezoar: report of a case| journal = Surgery Today| volume = 26| issue = 1| pages = 68–70| year = 1996| pmid = 8680127| doi = 10.1007/BF00311997| name-list-style=vanc| author2 = Nakatani K| author3 = Ishii H| display-authors = 3| last4 = Paku| first4 = Shuuichi| last5 = Kasamatsu| first5 = Minoru| last6 = Sekiya| first6 = Nao| last7 = Nakano| first7 = Hiroshige| s2cid = 24976010}}</ref>
Magnesium oxide is used for relief of heartburn and indigestion, as an [[antacid]], magnesium supplement, and as a short-term [[laxative]]. It is also used to improve symptoms of [[indigestion]]. Side effects of magnesium oxide may include nausea and cramping.<ref>[https://www.medlineplus.gov/druginfo/meds/a601074.html Magnesium Oxide]. MedlinePlus. Last reviewed 02/01/2009</ref> In quantities sufficient to obtain a laxative effect, side effects of long-term use may rarely cause [[enterolith]]s to form, resulting in [[bowel obstruction]].<ref>{{cite journal| author = Tatekawa Y| title = Small bowel obstruction caused by a medication bezoar: report of a case| journal = Surgery Today| volume = 26| issue = 1| pages = 68–70| year = 1996| pmid = 8680127| doi = 10.1007/BF00311997| name-list-style=vanc| author2 = Nakatani K| author3 = Ishii H| display-authors = 3| last4 = Paku| first4 = Shuuichi| last5 = Kasamatsu| first5 = Minoru| last6 = Sekiya| first6 = Nao| last7 = Nakano| first7 = Hiroshige| s2cid = 24976010}}</ref>


===Waste treatment===
===Waste treatment===
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* As a food additive, it is used as an [[anticaking agent]]. It is known to the US [[Food and Drug Administration]] for cacao products; canned peas; and frozen dessert.<ref>{{cite web |title=Compound Summary for CID 14792 – Magnesium Oxide |url=https://pubchem.ncbi.nlm.nih.gov/compound/magnesium_oxide |publisher=PubChem}}</ref> It has an [[E number]] of E530.
* As a food additive, it is used as an [[anticaking agent]]. It is known to the US [[Food and Drug Administration]] for cacao products; canned peas; and frozen dessert.<ref>{{cite web |title=Compound Summary for CID 14792 – Magnesium Oxide |url=https://pubchem.ncbi.nlm.nih.gov/compound/magnesium_oxide |publisher=PubChem}}</ref> It has an [[E number]] of E530.
* As a reagent in the installation of the carboxybenzyl (Cbz) group using [[benzyl chloroformate]] in [[ethyl acetate|EtOAc]] for the [[protecting group|N-protection]] of [[amine]]s and [[amide]]s.<ref>{{Cite journal|last=Dymicky|first=M.|date=1989-02-01|title=Preparation of Carbobenzoxy-<small>L</small>-Tyrosine Methyl and Ethyl Esters and of the Corresponding Carbobenzoxy Hydrazides|journal=Organic Preparations and Procedures International|volume=21|issue=1|pages=83–90|doi=10.1080/00304948909356350|issn=0030-4948}}</ref>
* As a reagent in the installation of the carboxybenzyl (Cbz) group using [[benzyl chloroformate]] in [[ethyl acetate|EtOAc]] for the [[protecting group|N-protection]] of [[amine]]s and [[amide]]s.<ref>{{Cite journal|last=Dymicky|first=M.|date=1989-02-01|title=Preparation of Carbobenzoxy-<small>L</small>-Tyrosine Methyl and Ethyl Esters and of the Corresponding Carbobenzoxy Hydrazides|journal=Organic Preparations and Procedures International|volume=21|issue=1|pages=83–90|doi=10.1080/00304948909356350|issn=0030-4948}}</ref>
* [[Doping (semiconductor)|Doping]] MgO (about 1–5% by weight) into [[hydroxyapatite]], a [[bioceramic]] mineral, increases the [[fracture toughness]] by migrating to grain boundaries, where it reduces grain size and changes the fracture mode from [[intergranular fracture|intergranular]] to [[transgranular fracture|transgranular]].<ref>{{cite journal |doi=10.1016/j.ceramint.2013.04.098 |last1=Tan |first1=C.Y. |last2=Yaghoubi |first2=A. |last3=Ramesh |first3=S. |last4=Adzila |first4=S. |last5=Purbolaksono |first5=J. |last6=Hassan |first6=M.A. |last7=Kutty |first7=M.G. |date=December 2013 |title=Sintering and mechanical properties of MgO-doped nanocrystalline hydroxyapatite |url=http://www.aun.edu.eg/reserches_files/13211.pdf |journal=Ceramics International |volume=39 |issue=8 |pages=8979–8983 |access-date=2015-08-08 |archive-date=2017-03-12 |archive-url=https://web.archive.org/web/20170312033742/http://www.aun.edu.eg/reserches_files/13211.pdf |url-status=dead }}</ref><ref >{{cite journal | last1=Tan | first1=Chou Yong | last2=Singh | first2=Ramesh | last3=Tolouei | first3=R. | last4=Sopyan | first4=Iis | last5=Teng | first5=Wan Dung | title=Synthesis of High Fracture Toughness of Hydroxyapatite Bioceramics | journal=Advanced Materials Research | volume=264-265 | year=2011 | issn=1662-8985 | doi=10.4028/www.scientific.net/amr.264-265.1849 | pages=1849–1855| s2cid=137578750 }}</ref>  
* [[Doping (semiconductor)|Doping]] MgO (about 1–5% by weight) into [[hydroxyapatite]], a [[bioceramic]] mineral, increases the [[fracture toughness]] by migrating to grain boundaries, where it reduces grain size and changes the fracture mode from [[intergranular fracture|intergranular]] to [[transgranular fracture|transgranular]].<ref>{{cite journal |doi=10.1016/j.ceramint.2013.04.098 |last1=Tan |first1=C.Y. |last2=Yaghoubi |first2=A. |last3=Ramesh |first3=S. |last4=Adzila |first4=S. |last5=Purbolaksono |first5=J. |last6=Hassan |first6=M.A. |last7=Kutty |first7=M.G. |date=December 2013 |title=Sintering and mechanical properties of MgO-doped nanocrystalline hydroxyapatite |url=http://www.aun.edu.eg/reserches_files/13211.pdf |journal=Ceramics International |volume=39 |issue=8 |pages=8979–8983 |access-date=2015-08-08 |archive-date=2017-03-12 |archive-url=https://web.archive.org/web/20170312033742/http://www.aun.edu.eg/reserches_files/13211.pdf }}</ref><ref >{{cite journal | last1=Tan | first1=Chou Yong | last2=Singh | first2=Ramesh | last3=Tolouei | first3=R. | last4=Sopyan | first4=Iis | last5=Teng | first5=Wan Dung | title=Synthesis of High Fracture Toughness of Hydroxyapatite Bioceramics | journal=Advanced Materials Research | volume=264-265 | year=2011 | issn=1662-8985 | doi=10.4028/www.scientific.net/amr.264-265.1849 | pages=1849–1855| s2cid=137578750 }}</ref>  
* Pressed MgO is used as an optical material. It is transparent from 0.3 to 7&nbsp;μm. The [[refractive index]] is 1.72 at 1&nbsp;μm and the [[Abbe number]] is 53.58. It is sometimes known by the [[Eastman Kodak]] trademarked name Irtran-5, although this designation is obsolete. Crystalline pure MgO is available commercially and has a small use in infrared optics.<ref>{{cite journal|title=Index of Refraction of Magnesium Oxide|author1=Stephens, Robert E.|author2=Malitson, Irving H.|name-list-style=amp|journal=Journal of Research of the National Bureau of Standards|volume=49|issue=4|year=1952|pages=249–252|doi=10.6028/jres.049.025|doi-access=free}}</ref>
* Pressed MgO is used as an optical material. It is transparent from 0.3 to 7&nbsp;μm. The [[refractive index]] is 1.72 at 1&nbsp;μm and the [[Abbe number]] is 53.58. It is sometimes known by the [[Eastman Kodak]] trademarked name Irtran-5, although this designation is obsolete. Crystalline pure MgO is available commercially and has a small use in infrared optics.<ref>{{cite journal|title=Index of Refraction of Magnesium Oxide|author1=Stephens, Robert E.|author2=Malitson, Irving H.|name-list-style=amp|journal=Journal of Research of the National Bureau of Standards|volume=49|issue=4|year=1952|pages=249–252|doi=10.6028/jres.049.025|doi-access=free}}</ref>
* An aerosolized solution of MgO is used in library science and collections management for the [[deacidification]] of at-risk paper items. In this process, the alkalinity of MgO (and similar compounds) neutralizes the relatively high acidity characteristic of low-quality paper, thus slowing the rate of deterioration.<ref name="LibraryofCongress">{{cite web|title=Mass Deacidification: Saving the Written Word|url=https://www.loc.gov/preservation/scientists/projects/mass_deacid.html|work=Library of Congress|access-date=26 September 2011}}</ref>
* An aerosolized solution of MgO is used in library science and collections management for the [[deacidification]] of at-risk paper items. In this process, the alkalinity of MgO (and similar compounds) neutralizes the relatively high acidity characteristic of low-quality paper, thus slowing the rate of deterioration.<ref name="LibraryofCongress">{{cite web|title=Mass Deacidification: Saving the Written Word|url=https://www.loc.gov/preservation/scientists/projects/mass_deacid.html|work=Library of Congress|access-date=26 September 2011}}</ref>
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| bibcode = 2004NatMa...3..862P | s2cid = 33709206  
| bibcode = 2004NatMa...3..862P | s2cid = 33709206  
}}</ref> versus 40–60&nbsp;% with aluminium oxide.<ref>{{Cite journal | last1 = Monsma | first1 = D. J. | last2 = Parkin | first2 = S. S. P. | doi = 10.1063/1.127097 | title = Spin polarization of tunneling current from ferromagnet/Al<sub>2</sub>O<sub>3</sub> interfaces using copper-doped aluminum superconducting films | journal = Applied Physics Letters | volume = 77 | issue = 5 | page = 720 | year = 2000 |bibcode = 2000ApPhL..77..720M }}</ref> The value of [[tunnel magnetoresistance]] is also significantly higher for MgO (600% at room temperature and 1,100&nbsp;% at 4.2 K<ref>{{Cite journal | last1 = Ikeda | first1 = S. | last2 = Hayakawa | first2 = J. | last3 = Ashizawa | first3 = Y. | last4 = Lee | first4 = Y. M. | last5 = Miura | first5 = K. | last6 = Hasegawa | first6 = H. | last7 = Tsunoda | first7 = M. | last8 = Matsukura | first8 = F. | last9 = Ohno | first9 = H. | doi = 10.1063/1.2976435 | title = Tunnel magnetoresistance of 604% at 300 K by suppression of Ta diffusion in CoFeB/MgO/CoFeB pseudo-spin-valves annealed at high temperature | journal = Applied Physics Letters | volume = 93 | issue = 8 | page = 082508 | year = 2008 |bibcode = 2008ApPhL..93h2508I | s2cid = 122271110 }}</ref>) than Al<sub>2</sub>O<sub>3</sub> (ca. 70% at room temperature<ref>{{Cite journal | last1 = Wang | first1 = D. | last2 = Nordman | first2 = C. | last3 = Daughton | first3 = J. M. | last4 = Qian | first4 = Z. | last5 = Fink | first5 = J. | doi = 10.1109/TMAG.2004.830219 | title = 70% TMR at Room Temperature for SDT Sandwich Junctions with CoFeB as Free and Reference Layers | journal = IEEE Transactions on Magnetics | volume = 40 | issue = 4 | page = 2269 | year = 2004 | citeseerx = 10.1.1.476.8544 | bibcode = 2004ITM....40.2269W | s2cid = 20439632 }}</ref>).
}}</ref> versus 40–60&nbsp;% with aluminium oxide.<ref>{{Cite journal | last1 = Monsma | first1 = D. J. | last2 = Parkin | first2 = S. S. P. | doi = 10.1063/1.127097 | title = Spin polarization of tunneling current from ferromagnet/Al<sub>2</sub>O<sub>3</sub> interfaces using copper-doped aluminum superconducting films | journal = Applied Physics Letters | volume = 77 | issue = 5 | page = 720 | year = 2000 |bibcode = 2000ApPhL..77..720M }}</ref> The value of [[tunnel magnetoresistance]] is also significantly higher for MgO (600% at room temperature and 1,100&nbsp;% at 4.2 K<ref>{{Cite journal | last1 = Ikeda | first1 = S. | last2 = Hayakawa | first2 = J. | last3 = Ashizawa | first3 = Y. | last4 = Lee | first4 = Y. M. | last5 = Miura | first5 = K. | last6 = Hasegawa | first6 = H. | last7 = Tsunoda | first7 = M. | last8 = Matsukura | first8 = F. | last9 = Ohno | first9 = H. | doi = 10.1063/1.2976435 | title = Tunnel magnetoresistance of 604% at 300 K by suppression of Ta diffusion in CoFeB/MgO/CoFeB pseudo-spin-valves annealed at high temperature | journal = Applied Physics Letters | volume = 93 | issue = 8 | page = 082508 | year = 2008 |bibcode = 2008ApPhL..93h2508I | s2cid = 122271110 }}</ref>) than Al<sub>2</sub>O<sub>3</sub> (ca. 70% at room temperature<ref>{{Cite journal | last1 = Wang | first1 = D. | last2 = Nordman | first2 = C. | last3 = Daughton | first3 = J. M. | last4 = Qian | first4 = Z. | last5 = Fink | first5 = J. | doi = 10.1109/TMAG.2004.830219 | title = 70% TMR at Room Temperature for SDT Sandwich Junctions with CoFeB as Free and Reference Layers | journal = IEEE Transactions on Magnetics | volume = 40 | issue = 4 | page = 2269 | year = 2004 | citeseerx = 10.1.1.476.8544 | bibcode = 2004ITM....40.2269W | s2cid = 20439632 }}</ref>).
* MgO is a common pressure transmitting medium used in high pressure apparatuses like the [[multi-anvil press]].<ref>{{Cite journal |last1=Wang |first1=Haikuo |last2=He |first2=Duanwei |last3=Yan |first3=Xiaozhi |last4=Xu |first4=Chao |last5=Guan |first5=Junwei |last6=Tan |first6=Ning |last7=Wang |first7=Wendan |date=December 2011 |title=Quantitative measurements of pressure gradients for the pyrophyllite and magnesium oxide pressure-transmitting mediums to 8 GPa in a large-volume cubic cell |url=http://www.tandfonline.com/doi/abs/10.1080/08957959.2011.614238 |journal=High Pressure Research |language=en |volume=31 |issue=4 |pages=581–591 |doi=10.1080/08957959.2011.614238 |bibcode=2011HPR....31..581W |issn=0895-7959}}</ref>
* MgO is a common pressure transmitting medium used in high pressure apparatuses like the [[multi-anvil press]].<ref>{{Cite journal |last1=Wang |first1=Haikuo |last2=He |first2=Duanwei |last3=Yan |first3=Xiaozhi |last4=Xu |first4=Chao |last5=Guan |first5=Junwei |last6=Tan |first6=Ning |last7=Wang |first7=Wendan |date=December 2011 |title=Quantitative measurements of pressure gradients for the pyrophyllite and magnesium oxide pressure-transmitting mediums to 8 GPa in a large-volume cubic cell |url=http://www.tandfonline.com/doi/abs/10.1080/08957959.2011.614238 |journal=High Pressure Research |language=en |volume=31 |issue=4 |pages=581–591 |doi=10.1080/08957959.2011.614238 |bibcode=2011HPR....31..581W |issn=0895-7959|url-access=subscription }}</ref>


===Brake lining===
===Brake lining===
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=== Thin film transistors ===
=== Thin film transistors ===
In [[thin film transistors|thin film transistors(TFTs)]], MgO is often used as a dielectric material or an insulator due to its high thermal stability, excellent insulating properties, and wide [[bandgap]].<ref>{{cite web |url=https://www.sputtertargets.net/blog/magnesium-oxide-target-in-the-production-of-thin-film-transistors.html |title=Magnesium Oxide Target in Thin-Film Transistors Production |last=Green |first=Julissa |date=Apr 24, 2024 |publisher=Stanford Advanced Materials |website=Sputter Targets |access-date=Oct 30, 2024}}</ref> Optimized IGZO/MgO TFTs demonstrated an [[electron mobility]] of 1.63 cm²/Vs, an on/off current ratio of 10⁶, and a subthreshold swing of 0.50 V/decade at −0.11 V.<ref>{{cite journal |last1=Su |first1=Zhan |last2=Zhang |first2=Xiao |year=2024 |title=Effect of substrate temperature on growth mechanism and properties of PEALD-MgO dielectric films for amorphous-IGZO TFTs |journal=Surface and Coatings Technology |volume=483 |page=130819 |doi=10.1016/j.surfcoat.2024.130819}}</ref> These TFTs are integral to low-power applications, wearable devices, and radiation-hardened electronics, contributing to enhanced efficiency and durability across diverse domains.<ref>{{cite journal |last1=Yu |first1=Fangzhou |last2=Hong |first2=Wen |year=2021 |title=MgZnO-Based Negative Capacitance Transparent Thin-Film Transistor Built on Glass |journal=IEEE Journal of the Electron Devices Society |volume=9 |pages=798–803 |doi=10.1109/JEDS.2021.3108904 |doi-access=free}}</ref><ref>{{cite journal |last1=Zhao |first1=Cheng |last2=Li |first2=Jun |year=2017 |title=Mg Doping to Simultaneously Improve the Electrical Performance and Stability of MgInO Thin-Film Transistors |journal=IEEE Transactions on Electron Devices |volume=64 |issue=5 |pages=2216–2220 |doi=10.1109/TED.2017.2678544|bibcode=2017ITED...64.2216Z }}</ref>
In [[thin film transistors|thin film transistors(TFTs)]], MgO is often used as a dielectric material or an insulator due to its high thermal stability, excellent insulating properties, and wide [[bandgap]].<ref>{{cite web |url=https://www.sputtertargets.net/blog/magnesium-oxide-target-in-the-production-of-thin-film-transistors.html |title=Magnesium Oxide Target in Thin-Film Transistors Production |last=Green |first=Julissa |date=Apr 24, 2024 |publisher=Stanford Advanced Materials |website=Sputter Targets |access-date=Oct 30, 2024}}</ref> Optimized IGZO/MgO TFTs demonstrated an [[electron mobility]] of 1.63 cm<sup>2</sup>/Vs, an on/off current ratio of 1,000,000:1, and a subthreshold swing of 0.50 V/decade at −0.11 V.<ref>{{cite journal |last1=Su |first1=Zhan |last2=Zhang |first2=Xiao |year=2024 |title=Effect of substrate temperature on growth mechanism and properties of PEALD-MgO dielectric films for amorphous-IGZO TFTs |journal=Surface and Coatings Technology |volume=483 |article-number=130819 |doi=10.1016/j.surfcoat.2024.130819}}</ref> These TFTs are integral to low-power applications, wearable devices, and radiation-hardened electronics, contributing to enhanced efficiency and durability across diverse domains.<ref>{{cite journal |last1=Yu |first1=Fangzhou |last2=Hong |first2=Wen |year=2021 |title=MgZnO-Based Negative Capacitance Transparent Thin-Film Transistor Built on Glass |journal=IEEE Journal of the Electron Devices Society |volume=9 |pages=798–803 |doi=10.1109/JEDS.2021.3108904 |bibcode=2021IJEDS...9..798Y |doi-access=free}}</ref><ref>{{cite journal |last1=Zhao |first1=Cheng |last2=Li |first2=Jun |year=2017 |title=Mg Doping to Simultaneously Improve the Electrical Performance and Stability of MgInO Thin-Film Transistors |journal=IEEE Transactions on Electron Devices |volume=64 |issue=5 |pages=2216–2220 |doi=10.1109/TED.2017.2678544|bibcode=2017ITED...64.2216Z }}</ref>


===Historical uses===
===Historical uses===

Latest revision as of 23:42, 18 September 2025

Template:Short description Template:Chembox Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water (MgO + H2O → Mg(OH)2), but it can be reversed by heating it to remove moisture.

Magnesium oxide was historically known as magnesia alba (literally, the white mineral from Magnesia), to differentiate it from magnesia nigra, a black mineral containing what is now known as manganese.

Related oxides

While "magnesium oxide" normally refers to MgO, the compound magnesium peroxide MgO2 is also known. According to evolutionary crystal structure prediction,[1] MgO2 is thermodynamically stable at pressures above 116 GPa (gigapascals), and a semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa. Because of its stability, MgO is used as a model system for investigating vibrational properties of crystals.[2]

Electric properties

Pure MgO is not conductive and has a high resistance to electric current at room temperature. The pure powder of MgO has a relative permittivity inbetween 3.2 to 9.9 k with an approximate dielectric loss of tan(δ) > 2.16x103 at 1kHz.[3][4][5]

Production

Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide. The latter is obtained by the treatment of magnesium chloride Template:Chem solutions, typically seawater, with limewater or milk of lime.[6]

Mg2+ + Ca(OH)2 → Mg(OH)2 + Ca2+

Calcining at different temperatures produces magnesium oxide of different reactivity. High temperatures 1500 – 2000 °C diminish the available surface area and produces dead-burned (often called dead burnt) magnesia, an unreactive form used as a refractory. Calcining temperatures 1000 – 1500 °C produce hard-burned magnesia, which has limited reactivity and calcining at lower temperature, (700–1000 °C) produces light-burned magnesia, a reactive form, also known as caustic calcined magnesia. Although some decomposition of the carbonate to oxide occurs at temperatures below 700 °C, the resulting materials appear to reabsorb carbon dioxide from the air.Script error: No such module "Unsubst".

Applications

Refractory insulator

MgO is prized as a refractory material, i.e. a solid that is physically and chemically stable at high temperatures. It has the useful attributes of high thermal conductivity and low electrical conductivity. According to a 2006 reference book:[7]

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By far the largest consumer of magnesia worldwide is the refractory industry, which consumed about 56% of the magnesia in the United States in 2004, the remaining 44% being used in agricultural, chemical, construction, environmental, and other industrial applications.

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MgO is used as a refractory material for crucibles. It is also used as an insulator in heat-resistant electrical cable.

Biomedical

Among metal oxide nanoparticles, magnesium oxide nanoparticles (MgO NPs) have distinct physicochemical and biological properties, including biocompatibility, biodegradability, high bioactivity, significant antibacterial properties, and good mechanical properties, which make it a good choice as a reinforcement in composites.[8]

Heating elements

It is used extensively as an electrical insulator in tubular construction heating elements as in electric stove and cooktop heating elements. There are several mesh sizes available and most commonly used ones are 40 and 80 mesh per the American Foundry Society. The extensive use is due to its high dielectric strength and average thermal conductivity. MgO is usually crushed and compacted with minimal airgaps or voids.

Cement

MgO is one of the components in Portland cement in dry process plants.

Sorel cement uses MgO as the main component in combination with MgCl2 and water.

Fertilizer

MgO has an important place as a commercial plant fertilizer[9] and as animal feed.[10]

Fireproofing

It is a principal fireproofing ingredient in construction materials. As a construction material, magnesium oxide wallboards have several attractive characteristics: fire resistance, termite resistance, moisture resistance, mold and mildew resistance, and strength, but also a severe downside as it attracts moisture and can cause moisture damage to surrounding materials.[11][7][1]

Medical

Magnesium oxide is used for relief of heartburn and indigestion, as an antacid, magnesium supplement, and as a short-term laxative. It is also used to improve symptoms of indigestion. Side effects of magnesium oxide may include nausea and cramping.[12] In quantities sufficient to obtain a laxative effect, side effects of long-term use may rarely cause enteroliths to form, resulting in bowel obstruction.[13]

Waste treatment

Magnesium oxide is used extensively in the soil and groundwater remediation, wastewater treatment, drinking water treatment, air emissions treatment, and waste treatment industries for its acid buffering capacity and related effectiveness in stabilizing dissolved heavy metal species.Template:According to whom

Many heavy metals species, such as lead and cadmium, are least soluble in water at mildly basic conditions (pH in the range 8–11). Solubility of metals increases their undesired bioavailability and mobility in soil and groundwater. Granular MgO is often blended into metals-contaminating soil or waste material, which is also commonly of a low pH (acidic), in order to drive the pH into the 8–10 range. Metal-hydroxide complexes tend to precipitate out of aqueous solution in the pH range of 8–10.

MgO is packed in bags around transuranic waste in the disposal cells (panels) at the Waste Isolation Pilot Plant, as a Template:CO2 getter to minimize the complexation of uranium and other actinides by carbonate ions and so to limit the solubility of radionuclides. The use of MgO is preferred over CaO since the resulting hydration product (Template:Chem) is less soluble and releases less hydration heat. Another advantage is to impose a lower pH value (about 10.5) in case of accidental water ingress into the dry salt layers, in contast to the more soluble Template:Chem which would create a higher pH of 12.5 (strongly alkaline conditions). The Template:Chem cation being the second most abundant cation in seawater and in rocksalt, the potential release of magnesium ions dissolving in brines intruding the deep geological repository is also expected to minimize the geochemical disruption.[14]

Niche uses

File:MgOcrystal.JPG
Unpolished MgO crystal
  • As a food additive, it is used as an anticaking agent. It is known to the US Food and Drug Administration for cacao products; canned peas; and frozen dessert.[15] It has an E number of E530.
  • As a reagent in the installation of the carboxybenzyl (Cbz) group using benzyl chloroformate in EtOAc for the N-protection of amines and amides.[16]
  • Doping MgO (about 1–5% by weight) into hydroxyapatite, a bioceramic mineral, increases the fracture toughness by migrating to grain boundaries, where it reduces grain size and changes the fracture mode from intergranular to transgranular.[17][18]
  • Pressed MgO is used as an optical material. It is transparent from 0.3 to 7 μm. The refractive index is 1.72 at 1 μm and the Abbe number is 53.58. It is sometimes known by the Eastman Kodak trademarked name Irtran-5, although this designation is obsolete. Crystalline pure MgO is available commercially and has a small use in infrared optics.[19]
  • An aerosolized solution of MgO is used in library science and collections management for the deacidification of at-risk paper items. In this process, the alkalinity of MgO (and similar compounds) neutralizes the relatively high acidity characteristic of low-quality paper, thus slowing the rate of deterioration.[20]
  • Magnesium oxide is used as an oxide barrier in spin-tunneling devices. Owing to the crystalline structure of its thin films, which can be deposited by magnetron sputtering, for example, it shows characteristics superior to those of the commonly used amorphous Al2O3. In particular, spin polarization of about 85% has been achieved with MgO[21] versus 40–60 % with aluminium oxide.[22] The value of tunnel magnetoresistance is also significantly higher for MgO (600% at room temperature and 1,100 % at 4.2 K[23]) than Al2O3 (ca. 70% at room temperature[24]).
  • MgO is a common pressure transmitting medium used in high pressure apparatuses like the multi-anvil press.[25]

Brake lining

Magnesia is used in brake linings for its heat conductivity and intermediate hardness.[26] It helps dissipate heat from friction surfaces, preventing overheating, while minimizing wear on metal components.[27] Its stability under high temperatures ensures reliable and durable braking performance in automotive and industrial applications.[28]

Thin film transistors

In thin film transistors(TFTs), MgO is often used as a dielectric material or an insulator due to its high thermal stability, excellent insulating properties, and wide bandgap.[29] Optimized IGZO/MgO TFTs demonstrated an electron mobility of 1.63 cm2/Vs, an on/off current ratio of 1,000,000:1, and a subthreshold swing of 0.50 V/decade at −0.11 V.[30] These TFTs are integral to low-power applications, wearable devices, and radiation-hardened electronics, contributing to enhanced efficiency and durability across diverse domains.[31][32]

Historical uses

Precautions

Inhalation of magnesium oxide fumes can cause metal fume fever.[34]

See also

Notes

Template:Notelist

References

Template:Reflist

External links

Template:Magnesium compounds Template:Antacids Template:Oxides Template:Oxygen compounds Template:Authority control

  1. ↑ Script error: No such module "Citation/CS1".
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  6. ↑ Template:Ullmann
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  8. ↑ Script error: No such module "Citation/CS1".
  9. ↑ Nutrient Science. fertilizer101.org. Retrieved on 2017-04-26.
  10. ↑ Magnesium oxide for the Animal Feed Industry. lehvoss.de
  11. ↑ Script error: No such module "Citation/CS1".
  12. ↑ Magnesium Oxide. MedlinePlus. Last reviewed 02/01/2009
  13. ↑ Script error: No such module "Citation/CS1".
  14. ↑ wipp.energy.gov Step-By-Step Guide for Waste Handling at WIPP. Waste Isolation Pilot Plant. wipp.energy.gov
  15. ↑ Script error: No such module "citation/CS1".
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  31. ↑ Script error: No such module "Citation/CS1".
  32. ↑ Script error: No such module "Citation/CS1".
  33. ↑ Script error: No such module "Citation/CS1".
  34. ↑ Magnesium Oxide. National Pollutant Inventory, Government of Australia.
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