Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)
Identifieur interne : 001443 ( Istex/Corpus ); précédent : 001442; suivant : 001444Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)
Auteurs : Richard V. Morris ; Howard V. Lauer Jr. ; Charles A. Lawson ; Everett K. Gibson Jr. ; Georg Ann Nace ; Cheri StewartSource :
- Journal of Geophysical Research: Solid Earth [ 0148-0227 ] ; 1985-03-10.
Abstract
Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mössbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation‐deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near‐IR to intense absorption in the near‐UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal‐field band at lowest energy, assigned to the envelope of the components of the split cubic 4T1 level, is near 0.86, 0.91, 0.92, and 0.98 μm at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mössbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about −110°C. The maximum shifts observed were on the order of about 0.02 μm shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal‐field bands increases with increasing mean particle diameter over the range 0.1–0.8 μm; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic 4T1 band shifts longward by about 0.02 μm with decreasing mean particle diameter over the same range; this trend is consistent with wavelength‐dependent scattering. The cation‐deficient magnetite powders are very strong absorbers throughout the near‐UV, visible and near‐IR; their spectral properties are independent of temperature between about −110 and 20°C.
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DOI: 10.1029/JB090iB04p03126
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<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title xml:lang="en">Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title><author wicri:is="90%"><name sortKey="Morris, Richard V" sort="Morris, Richard V" uniqKey="Morris R" first="Richard V." last="Morris">Richard V. Morris</name></author><author wicri:is="90%"><name sortKey="Lauer Jr, Howard V" sort="Lauer Jr, Howard V" uniqKey="Lauer Jr H" first="Howard V." last="Lauer Jr.">Howard V. Lauer Jr.</name></author><author wicri:is="90%"><name sortKey="Lawson, Charles A" sort="Lawson, Charles A" uniqKey="Lawson C" first="Charles A." last="Lawson">Charles A. Lawson</name></author><author wicri:is="90%"><name sortKey="Gibson Jr, Everett K" sort="Gibson Jr, Everett K" uniqKey="Gibson Jr E" first="Everett K." last="Gibson Jr.">Everett K. Gibson Jr.</name></author><author wicri:is="90%"><name sortKey="Nace, Georg Ann" sort="Nace, Georg Ann" uniqKey="Nace G" first="Georg Ann" last="Nace">Georg Ann Nace</name></author><author wicri:is="90%"><name sortKey="Stewart, Cheri" sort="Stewart, Cheri" uniqKey="Stewart C" first="Cheri" last="Stewart">Cheri Stewart</name></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0</idno><date when="1985" year="1985">1985</date><idno type="doi">10.1029/JB090iB04p03126</idno><idno type="url">https://api.istex.fr/document/ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">001443</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a" type="main" xml:lang="en">Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title><author wicri:is="90%"><name sortKey="Morris, Richard V" sort="Morris, Richard V" uniqKey="Morris R" first="Richard V." last="Morris">Richard V. Morris</name></author><author wicri:is="90%"><name sortKey="Lauer Jr, Howard V" sort="Lauer Jr, Howard V" uniqKey="Lauer Jr H" first="Howard V." last="Lauer Jr.">Howard V. Lauer Jr.</name></author><author wicri:is="90%"><name sortKey="Lawson, Charles A" sort="Lawson, Charles A" uniqKey="Lawson C" first="Charles A." last="Lawson">Charles A. Lawson</name></author><author wicri:is="90%"><name sortKey="Gibson Jr, Everett K" sort="Gibson Jr, Everett K" uniqKey="Gibson Jr E" first="Everett K." last="Gibson Jr.">Everett K. Gibson Jr.</name></author><author wicri:is="90%"><name sortKey="Nace, Georg Ann" sort="Nace, Georg Ann" uniqKey="Nace G" first="Georg Ann" last="Nace">Georg Ann Nace</name></author><author wicri:is="90%"><name sortKey="Stewart, Cheri" sort="Stewart, Cheri" uniqKey="Stewart C" first="Cheri" last="Stewart">Cheri Stewart</name></author></analytic><monogr></monogr><series><title level="j">Journal of Geophysical Research: Solid Earth</title><title level="j" type="abbrev">J. Geophys. Res.</title><idno type="ISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="1985-03-10">1985-03-10</date><biblScope unit="volume">90</biblScope><biblScope unit="issue">B4</biblScope><biblScope unit="page" from="3126">3126</biblScope><biblScope unit="page" to="3144">3144</biblScope></imprint><idno type="ISSN">0148-0227</idno></series><idno type="istex">ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0</idno><idno type="DOI">10.1029/JB090iB04p03126</idno><idno type="ArticleID">4B1323</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0148-0227</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mössbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation‐deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near‐IR to intense absorption in the near‐UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal‐field band at lowest energy, assigned to the envelope of the components of the split cubic 4T1 level, is near 0.86, 0.91, 0.92, and 0.98 μm at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mössbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about −110°C. The maximum shifts observed were on the order of about 0.02 μm shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal‐field bands increases with increasing mean particle diameter over the range 0.1–0.8 μm; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic 4T1 band shifts longward by about 0.02 μm with decreasing mean particle diameter over the same range; this trend is consistent with wavelength‐dependent scattering. The cation‐deficient magnetite powders are very strong absorbers throughout the near‐UV, visible and near‐IR; their spectral properties are independent of temperature between about −110 and 20°C.</div></front></TEI><istex><corpusName>wiley</corpusName><author><json:item><name>Richard V. Morris</name></json:item><json:item><name>Howard V. Lauer Jr.</name></json:item><json:item><name>Charles A. Lawson</name></json:item><json:item><name>Everett K. Gibson Jr.</name></json:item><json:item><name>Georg Ann Nace</name></json:item><json:item><name>Cheri Stewart</name></json:item></author><articleId><json:string>4B1323</json:string></articleId><language><json:string>eng</json:string></language><abstract>Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mössbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation‐deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near‐IR to intense absorption in the near‐UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal‐field band at lowest energy, assigned to the envelope of the components of the split cubic 4T1 level, is near 0.86, 0.91, 0.92, and 0.98 μm at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mössbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about −110°C. The maximum shifts observed were on the order of about 0.02 μm shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal‐field bands increases with increasing mean particle diameter over the range 0.1–0.8 μm; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic 4T1 band shifts longward by about 0.02 μm with decreasing mean particle diameter over the same range; this trend is consistent with wavelength‐dependent scattering. The cation‐deficient magnetite powders are very strong absorbers throughout the near‐UV, visible and near‐IR; their spectral properties are independent of temperature between about −110 and 20°C.</abstract><qualityIndicators><score>8</score><pdfVersion>1.3</pdfVersion><pdfPageSize>596 x 810 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>0</keywordCount><abstractCharCount>2518</abstractCharCount><pdfWordCount>11857</pdfWordCount><pdfCharCount>90627</pdfCharCount><pdfPageCount>19</pdfPageCount><abstractWordCount>359</abstractWordCount></qualityIndicators><title>Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title><genre.original><json:string>article</json:string></genre.original><genre><json:string>article</json:string></genre><host><volume>90</volume><publisherId><json:string>JGRB</json:string></publisherId><pages><total>19</total><last>3144</last><first>3126</first></pages><issn><json:string>0148-0227</json:string></issn><issue>B4</issue><subject><json:item><value>EXPLORATION GEOPHYSICS</value></json:item><json:item><value>Magnetic and electrical methods</value></json:item><json:item><value>GEOMAGNETISM AND PALEOMAGNETISM</value></json:item><json:item><value>Rock and mineral magnetism</value></json:item><json:item><value>MINERAL PHYSICS</value></json:item><json:item><value>Optical, infrared, and Raman spectroscopy</value></json:item><json:item><value>PHYSICAL PROPERTIES OF ROCKS</value></json:item><json:item><value>Magnetic and electrical properties</value></json:item><json:item><value>PLANETARY SCIENCES: SOLID SURFACE PLANETS</value></json:item><json:item><value>Planetology: Solid Surface Planets and Satellites: Physical properties of materials</value></json:item></subject><genre><json:string>journal</json:string></genre><language><json:string>unknown</json:string></language><eissn><json:string>2156-2202</json:string></eissn><title>Journal of Geophysical Research: Solid Earth</title><doi><json:string>10.1002/(ISSN)2156-2202b</json:string></doi></host><publicationDate>1985</publicationDate><copyrightDate>1985</copyrightDate><doi><json:string>10.1029/JB090iB04p03126</json:string></doi><id>ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0</id><fulltext><json:item><original>true</original><mimetype>application/pdf</mimetype><extension>pdf</extension><uri>https://api.istex.fr/document/ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0/fulltext/pdf</uri></json:item><json:item><original>false</original><mimetype>application/zip</mimetype><extension>zip</extension><uri>https://api.istex.fr/document/ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a" type="main" xml:lang="en">Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>Blackwell Publishing Ltd</publisher><availability><p>WILEY</p></availability><date>1985</date></publicationStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a" type="main" xml:lang="en">Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title><author><persName><forename type="first">Richard V.</forename><surname>Morris</surname></persName></author><author><persName><forename type="first">Howard V.</forename><surname>Lauer Jr.</surname></persName></author><author><persName><forename type="first">Charles A.</forename><surname>Lawson</surname></persName></author><author><persName><forename type="first">Everett K.</forename><surname>Gibson Jr.</surname></persName></author><author><persName><forename type="first">Georg Ann</forename><surname>Nace</surname></persName></author><author><persName><forename type="first">Cheri</forename><surname>Stewart</surname></persName></author></analytic><monogr><title level="j">Journal of Geophysical Research: Solid Earth</title><title level="j" type="abbrev">J. Geophys. Res.</title><idno type="pISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><idno type="DOI">10.1002/(ISSN)2156-2202b</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="1985-03-10"></date><biblScope unit="volume">90</biblScope><biblScope unit="issue">B4</biblScope><biblScope unit="page" from="3126">3126</biblScope><biblScope unit="page" to="3144">3144</biblScope></imprint></monogr><idno type="istex">ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0</idno><idno type="DOI">10.1029/JB090iB04p03126</idno><idno type="ArticleID">4B1323</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1985</date></creation><langUsage><language ident="en">en</language></langUsage><abstract><p>Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mössbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation‐deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near‐IR to intense absorption in the near‐UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal‐field band at lowest energy, assigned to the envelope of the components of the split cubic 4T1 level, is near 0.86, 0.91, 0.92, and 0.98 μm at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mössbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about −110°C. The maximum shifts observed were on the order of about 0.02 μm shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal‐field bands increases with increasing mean particle diameter over the range 0.1–0.8 μm; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic 4T1 band shifts longward by about 0.02 μm with decreasing mean particle diameter over the same range; this trend is consistent with wavelength‐dependent scattering. The cation‐deficient magnetite powders are very strong absorbers throughout the near‐UV, visible and near‐IR; their spectral properties are independent of temperature between about −110 and 20°C.</p></abstract><textClass><keywords scheme="Journal Subject"><list><head>index-terms</head><item><term>EXPLORATION GEOPHYSICS</term></item><item><term>Magnetic and electrical methods</term></item><item><term>GEOMAGNETISM AND PALEOMAGNETISM</term></item><item><term>Rock and mineral magnetism</term></item><item><term>MINERAL PHYSICS</term></item><item><term>Optical, infrared, and Raman spectroscopy</term></item><item><term>PHYSICAL PROPERTIES OF ROCKS</term></item><item><term>Magnetic and electrical properties</term></item><item><term>PLANETARY SCIENCES: SOLID SURFACE PLANETS</term></item><item><term>Planetology: Solid Surface Planets and Satellites: Physical properties of materials</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="1983-10-17">Received</change><change when="1984-10-26">Registration</change><change when="1985-03-10">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><original>false</original><mimetype>text/plain</mimetype><extension>txt</extension><uri>https://api.istex.fr/document/ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Wiley, elements deleted: body"><istex:xmlDeclaration>version="1.0" encoding="UTF-8" standalone="yes"</istex:xmlDeclaration><istex:document><component type="serialArticle" version="2.0" xml:lang="en" xml:id="jgrb5204"><header><publicationMeta level="product"><doi>10.1002/(ISSN)2156-2202b</doi><issn type="print">0148-0227</issn><issn type="electronic">2156-2202</issn><idGroup><id type="product" value="JGRB"></id><id type="coden" value="JGREA2"></id></idGroup><titleGroup><title type="main" xml:lang="en" sort="JOURNAL OF GEOPHYSICAL RESEARCH: SOLID EARTH">Journal of Geophysical Research: Solid Earth</title><title type="short">J. 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Res.</title></titleGroup></publicationMeta><publicationMeta level="part" position="40"><doi>10.1002/jgrb.v90.B4</doi><idGroup><id type="focusSection" value="2"></id></idGroup><titleGroup><title type="focusSection" xml:lang="en">Journal of Geophysical Research: Solid Earth</title></titleGroup><numberingGroup><numbering type="journalVolume" number="90">90</numbering><numbering type="journalIssue">B4</numbering></numberingGroup><coverDate startDate="1985-03-10">10 March 1985</coverDate></publicationMeta><publicationMeta level="unit" type="article" position="170" status="forIssue"><doi>10.1029/JB090iB04p03126</doi><idGroup><id type="editorialOffice" value="4B1323"></id><id type="unit" value="JGRB5204"></id></idGroup><countGroup><count type="pageTotal" number="19"></count></countGroup><copyright ownership="thirdParty">Copyright 1985 by the American Geophysical Union.</copyright><eventGroup><event type="manuscriptReceived" date="1983-10-17"></event><event type="manuscriptAccepted" date="1984-10-26"></event><event type="publishedPrint" date="1985-03-10"></event><event type="firstOnline" date="2012-09-20"></event><event type="publishedOnlineFinalForm" date="2012-09-20"></event><event type="xmlConverted" agent="SPi Global Converter:AGUv1.0_TO_WileyML3Gv1.0.3 version:1.2; WileyML 3G Packaging Tool v1.0" date="2012-11-26"></event><event type="xmlConverted" agent="Converter:WILEY_ML3G_TO_WILEY_ML3GV2 version:3.8.8" date="2014-01-31"></event><event type="xmlConverted" agent="Converter:WML3G_To_WML3G version:4.1.7 mode:FullText,remove_FC" date="2014-10-30"></event></eventGroup><numberingGroup><numbering type="pageFirst">3126</numbering><numbering type="pageLast">3144</numbering></numberingGroup><subjectInfo><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/0900">EXPLORATION GEOPHYSICS</subject><subjectInfo><subject role="crossTerm" href="http://psi.agu.org/taxonomy5/0925">Magnetic and electrical methods</subject></subjectInfo><subject href="http://psi.agu.org/taxonomy5/1500">GEOMAGNETISM AND PALEOMAGNETISM</subject><subjectInfo><subject href="http://psi.agu.org/taxonomy5/1540">Rock and mineral magnetism</subject></subjectInfo><subject href="http://psi.agu.org/taxonomy5/3900">MINERAL PHYSICS</subject><subjectInfo><subject href="http://psi.agu.org/taxonomy5/3934">Optical, infrared, and Raman spectroscopy</subject></subjectInfo><subject href="http://psi.agu.org/taxonomy5/5100">PHYSICAL PROPERTIES OF ROCKS</subject><subjectInfo><subject href="http://psi.agu.org/taxonomy5/5109">Magnetic and electrical properties</subject></subjectInfo><subject href="http://psi.agu.org/taxonomy5/5400">PLANETARY SCIENCES: SOLID SURFACE PLANETS</subject><subjectInfo><subject href="http://psi.agu.org/taxonomy5/5460">Planetology: Solid Surface Planets and Satellites: Physical properties of materials</subject></subjectInfo></subjectInfo><selfCitationGroup><citation xml:id="jgrb5204-cit-0000" type="self"><author><familyName>Morris</familyName>, <givenNames>R. V.</givenNames></author>, <author><givenNames>H. V.</givenNames> <familyName>Lauer</familyName> <nameSuffix>Jr.</nameSuffix></author>, <author><givenNames>C. A.</givenNames> <familyName>Lawson</familyName></author>, <author><givenNames>E. K.</givenNames> <familyName>Gibson</familyName> <nameSuffix>Jr.</nameSuffix></author>, <author><givenNames>G. A.</givenNames> <familyName>Nace</familyName></author>, and <author><givenNames>C.</givenNames> <familyName>Stewart</familyName></author> (<pubYear year="1985">1985</pubYear>), <articleTitle>Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe<sub>2</sub>O<sub>3</sub>), maghemite (γ‐Fe<sub>2</sub>O<sub>3</sub>), magnetite (Fe<sub>3</sub>O<sub>4</sub>), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</articleTitle>, <journalTitle>J. Geophys. Res.</journalTitle>, <vol>90</vol>(<issue>B4</issue>), <pageFirst>3126</pageFirst>–<pageLast>3144</pageLast>, doi:<accessionId ref="info:doi/10.1029/JB090iB04p03126">10.1029/JB090iB04p03126</accessionId>.</citation></selfCitationGroup><linkGroup><link type="toTypesetVersion" href="file:JGRB.JGRB5204.pdf"></link></linkGroup></publicationMeta><contentMeta><titleGroup><title type="main">Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe<sub>2</sub>O<sub>3</sub>), maghemite (γ‐Fe<sub>2</sub>O<sub>3</sub>), magnetite (Fe<sub>3</sub>O<sub>4</sub>), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title><title type="shortAuthors">Morris ET AL.</title></titleGroup><creators><creator xml:id="jgrb5204-cr-0001"><personName><givenNames>Richard V.</givenNames><familyName>Morris</familyName></personName></creator><creator xml:id="jgrb5204-cr-0002"><personName><givenNames>Howard V.</givenNames><familyName>Lauer</familyName><nameSuffix>Jr.</nameSuffix></personName></creator><creator xml:id="jgrb5204-cr-0003"><personName><givenNames>Charles A.</givenNames><familyName>Lawson</familyName></personName></creator><creator xml:id="jgrb5204-cr-0004"><personName><givenNames>Everett K.</givenNames><familyName>Gibson</familyName><nameSuffix>Jr.</nameSuffix></personName></creator><creator xml:id="jgrb5204-cr-0005"><personName><givenNames>Georg Ann</givenNames><familyName>Nace</familyName></personName></creator><creator xml:id="jgrb5204-cr-0006"><personName><givenNames>Cheri</givenNames><familyName>Stewart</familyName></personName></creator></creators><abstractGroup><abstract type="main"><p xml:id="jgrb5204-para-0001">Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α‐Fe<sub>2</sub>O<sub>3</sub>), maghemite (γ‐Fe<sub>2</sub>O<sub>3</sub>), magnetite (Fe<sub>3</sub>O<sub>4</sub>), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mössbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation‐deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near‐IR to intense absorption in the near‐UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal‐field band at lowest energy, assigned to the envelope of the components of the split cubic <sup>4</sup><i>T</i><sub>1</sub> level, is near 0.86, 0.91, 0.92, and 0.98 μm at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mössbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about −110°C. The maximum shifts observed were on the order of about 0.02 μm shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal‐field bands increases with increasing mean particle diameter over the range 0.1–0.8 μm; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic <sup>4</sup><i>T</i><sub>1</sub> band shifts longward by about 0.02 μm with decreasing mean particle diameter over the same range; this trend is consistent with wavelength‐dependent scattering. The cation‐deficient magnetite powders are very strong absorbers throughout the near‐UV, visible and near‐IR; their spectral properties are independent of temperature between about −110 and 20°C.</p></abstract></abstractGroup></contentMeta></header></component></istex:document></istex:metadataXml><mods version="3.6"><titleInfo lang="en"><title>Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH)</title></titleInfo><titleInfo type="alternative" contentType="CDATA" lang="en"><title>Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe</title></titleInfo><name type="personal"><namePart type="given">Richard V.</namePart><namePart type="family">Morris</namePart></name><name type="personal"><namePart type="given">Howard V.</namePart><namePart type="family">Lauer Jr.</namePart></name><name type="personal"><namePart type="given">Charles A.</namePart><namePart type="family">Lawson</namePart></name><name type="personal"><namePart type="given">Everett K.</namePart><namePart type="family">Gibson Jr.</namePart></name><name type="personal"><namePart type="given">Georg Ann</namePart><namePart type="family">Nace</namePart></name><name type="personal"><namePart type="given">Cheri</namePart><namePart type="family">Stewart</namePart></name><typeOfResource>text</typeOfResource><genre type="article" displayLabel="article"></genre><originInfo><publisher>Blackwell Publishing Ltd</publisher><dateIssued encoding="w3cdtf">1985-03-10</dateIssued><dateCaptured encoding="w3cdtf">1983-10-17</dateCaptured><dateValid encoding="w3cdtf">1984-10-26</dateValid><edition>Morris, R. V., H. V. Lauer Jr., C. A. Lawson, E. K. Gibson Jr., G. A. Nace, and C. Stewart (1985), Spectral and other physicochemical properties of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH), J. Geophys. Res., 90(B4), 3126–3144, doi:10.1029/JB090iB04p03126.</edition><copyrightDate encoding="w3cdtf">1985</copyrightDate></originInfo><language><languageTerm type="code" authority="rfc3066">en</languageTerm><languageTerm type="code" authority="iso639-2b">eng</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract>Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α‐Fe2O3), maghemite (γ‐Fe2O3), magnetite (Fe3O4), goethite (α‐FeOOH), and lepidocrocite (γ‐FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C. Other physicochemical properties determined were mean particle diameter, particle shape, chemical composition, crystallographic phase, magnetic properties, and Mössbauer properties. Only the magnetite powders have significant departures from the stoichiometric phase; they are actually cation‐deficient magnetites having down to about 18.0 wt % FeO as compared with 31.0 wt % FeO for stoichiometric magnetite. A structured absorption edge due to crystal field transitions and extending from weak absorption in the near‐IR to intense absorption in the near‐UV is characteristic of the ferric oxides and oxyhydroxides and is responsible for their intense color. Particularly for hematite, the number and position of the spectral features are consistent with significant splitting of the degenerate cubic levels by noncubic components of the crystal field. The position of the crystal‐field band at lowest energy, assigned to the envelope of the components of the split cubic 4T1 level, is near 0.86, 0.91, 0.92, and 0.98 μm at room temperature for hematite, goethite, maghemite, and lepidocrocite, respectively. Comparison with Mössbauer data suggests covalent character increases sequentially through the aforementioned series. The positions of the spectra features are relatively independent of temperature down to about −110°C. The maximum shifts observed were on the order of about 0.02 μm shortward for the ferric oxyhydroxides. Variations in the magnitude of the reflectivity of the hematite powders as a function of mean particle diameter are consistent with scattering theory. The absorption strength of the crystal‐field bands increases with increasing mean particle diameter over the range 0.1–0.8 μm; visually this corresponds to a change in color from orange to deep purple. The position of the split cubic 4T1 band shifts longward by about 0.02 μm with decreasing mean particle diameter over the same range; this trend is consistent with wavelength‐dependent scattering. The cation‐deficient magnetite powders are very strong absorbers throughout the near‐UV, visible and near‐IR; their spectral properties are independent of temperature between about −110 and 20°C.</abstract><relatedItem type="host"><titleInfo><title>Journal of Geophysical Research: Solid Earth</title></titleInfo><titleInfo type="abbreviated"><title>J. Geophys. Res.</title></titleInfo><genre type="journal">journal</genre><subject><genre>index-terms</genre><topic authorityURI="http://psi.agu.org/taxonomy5/0900">EXPLORATION GEOPHYSICS</topic><topic authorityURI="http://psi.agu.org/taxonomy5/0925">Magnetic and electrical methods</topic><topic authorityURI="http://psi.agu.org/taxonomy5/1500">GEOMAGNETISM AND PALEOMAGNETISM</topic><topic authorityURI="http://psi.agu.org/taxonomy5/1540">Rock and mineral magnetism</topic><topic authorityURI="http://psi.agu.org/taxonomy5/3900">MINERAL PHYSICS</topic><topic authorityURI="http://psi.agu.org/taxonomy5/3934">Optical, infrared, and Raman spectroscopy</topic><topic authorityURI="http://psi.agu.org/taxonomy5/5100">PHYSICAL PROPERTIES OF ROCKS</topic><topic authorityURI="http://psi.agu.org/taxonomy5/5109">Magnetic and electrical properties</topic><topic authorityURI="http://psi.agu.org/taxonomy5/5400">PLANETARY SCIENCES: SOLID SURFACE PLANETS</topic><topic authorityURI="http://psi.agu.org/taxonomy5/5460">Planetology: Solid Surface Planets and Satellites: Physical properties of materials</topic></subject><identifier type="ISSN">0148-0227</identifier><identifier type="eISSN">2156-2202</identifier><identifier type="DOI">10.1002/(ISSN)2156-2202b</identifier><identifier type="CODEN">JGREA2</identifier><identifier type="PublisherID">JGRB</identifier><part><date>1985</date><detail type="volume"><caption>vol.</caption><number>90</number></detail><detail type="issue"><caption>no.</caption><number>B4</number></detail><extent unit="pages"><start>3126</start><end>3144</end><total>19</total></extent></part></relatedItem><identifier type="istex">ED9855DC70E9EC28D9486EE0C575EDAD96CB4CA0</identifier><identifier type="DOI">10.1029/JB090iB04p03126</identifier><identifier type="ArticleID">4B1323</identifier><accessCondition type="use and reproduction" contentType="copyright">Copyright 1985 by the American Geophysical Union.</accessCondition><recordInfo><recordContentSource>WILEY</recordContentSource></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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