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{{Redirect-distinguish|Tungsten sulfide|Tungsten trisulfide}} |
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⚫ | |ImageCaption2 = Left: WS<sub>2</sub> film on sapphire. Right: dark exfoliated WS<sub>2</sub> film floating on water |
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|Section1={{Chembox Identifiers |
|Section1={{Chembox Identifiers |
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|CASNo = 12138-09-9 |
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|CASNo_Ref = {{cascite|correct|CAS}} |
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|ChEBI_Ref = {{ebicite|correct|EBI}} |
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|ChEBI = 30521 |
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|StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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|StdInChI = 1S/2S.W |
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|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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|StdInChIKey = ITRNXVSDJBHYNJ-UHFFFAOYSA-N |
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|PubChem = 82938 |
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|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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|ChemSpiderID = 74837 |
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|InChI = 1S/2S.W |
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|InChIKey = ITRNXVSDJBHYNJ-UHFFFAOYSA-N |
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|SMILES = S=[W]=S |
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|EINECS = 235-243-3 |
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|Section2={{Chembox Properties |
|Section2={{Chembox Properties |
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|Formula = WS<sub>2</sub> |
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|MolarMass = 247.98 g/mol |
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|Appearance = Blue-gray powder<ref name=b1/> |
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|Density = 7.5 g/cm<sup>3</sup>, solid<ref name=b1/> |
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|MeltingPtC = 1250 |
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|MeltingPt_notes = decomposes<ref name=b1/> |
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|Solubility = Slightly soluble |
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|MagSus = +5850·10{{sup|−6}} cm<sup>3</sup>/mol<ref name=b92>{{RubberBible92nd|page=4.136}}</ref> |
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|BandGap = ~1.35 eV (optical, indirect, bulk)<ref name="bulkWS2_Bandgap">{{cite journal |last1=Kam |first1=K. K. |last2=Parkinson |first2=B. A. |title=Detailed photocurrent spectroscopy of the semiconducting group VIB transition metal dichalcogenides |journal=Journal of Physical Chemistry |date=February 1982 |volume=86 |issue=4 | pages=463–467 |doi=10.1021/j100393a010 }}</ref><ref name="BulkBandgap_TMDs">{{cite journal |last1=Baglio |first1=Joseph A. |last2=Calabrese |first2=Gary S. |last3=Kamieniecki |first3=Emil |last4=Kershaw |first4=Robert |last5=Kubiak |first5=Clifford P. |last6=Ricco |first6=Antonio J. |last7=Wold |first7=Aaron |last8=Wrighton |first8=Mark S. |last9=Zoski |first9=Glenn D. |title=Characterization of n-Type Semiconducting Tungsten Disulfide Photoanodes in Aqueous and Nonaqueous Electrolyte Solutions Photo-oxidation of Halides with High Efficiency |journal=J. Electrochem. Soc. |date=July 1982 |volume=129 |issue=7 |pages=1461–1472 |doi=10.1149/1.2124184 |bibcode=1982JElS..129.1461B |doi-access=free }}</ref> <br>~2.05 eV (optical, direct, monolayer)<ref name="Monolayer_bandgap">{{cite journal |last1=Gutiérrez |first1=Humberto |last2=Perea-López |first2=Nestor |last3=Elías |first3=Ana Laura |last4=Berkdemir | first4=Ayse |last5=Wang |first5=Bei |last6=Lv |first6=Ruitao |last7=López-Urías |first7=Florentino |last8=Crespi |first8=Vincent H. |last9=Terrones |first9=Humberto | last10=Terrones |first10=Mauricio |title=Extraordinary Room-Temperature Photoluminescence in Triangular WS2 Monolayers |journal=Nano Letters |date=November 2012 |volume=13 | issue=8 |pages=3447–3454 |doi=10.1021/nl3026357 |pmid=23194096 |arxiv=1208.1325|bibcode=2013NanoL..13.3447G |s2cid=207597527 }}</ref> |
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|Section3={{Chembox Structure |
|Section3={{Chembox Structure |
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|CrystalStruct = [[Molybdenite]] |
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|Coordination = [[Trigonal prism]]atic (W<sup>IV</sup>)<br/>Pyramidal (S<sup>2−</sup>) |
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⚫ | |OtherAnions = [[Tungsten(IV) oxide]]<br/>[[Tungsten diselenide]]<br/>[[Tungsten ditelluride]] |
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⚫ | |OtherCations = [[Molybdenum disulfide]]<br/>[[Tantalum disulfide]]<br/>[[Rhenium disulfide]] |
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'''Tungsten disulfide''' is an inorganic [[chemical compound]] composed of [[tungsten]] and [[sulfur]] with the chemical formula WS<sub>2</sub>. This compound is part of the group of materials called the [[Chalcogenide#Dichalcogenides|transition metal dichalcogenides]]. It occurs naturally as the rare mineral |
'''Tungsten disulfide''' is an inorganic [[chemical compound]] composed of [[tungsten]] and [[sulfur]] with the chemical formula WS<sub>2</sub>. This compound is part of the group of materials called the [[Chalcogenide#Dichalcogenides|transition metal dichalcogenides]]. It occurs naturally as the rare mineral ''tungstenite''. This material is a component of certain catalysts used for [[hydrodesulfurization]] and [[hydrodenitrification]]. |
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WS<sub>2</sub> adopts a layered structure similar, or [[ |
WS<sub>2</sub> adopts a layered structure similar, or [[isostructural|isotypic]] with [[molybdenum disulfide|MoS<sub>2</sub>]], instead with W atoms situated in trigonal prismatic [[coordination sphere]] (in place of Mo atoms). Owing to this layered structure, WS<sub>2</sub> forms [[non-carbon nanotube]]s, which were discovered after heating a thin sample of WS<sub>2</sub> in 1992.<ref name=Tenne1992/> |
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==Structure and physical properties== |
==Structure and physical properties== |
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[[File:WS2-Nb HRTEM2.jpg|thumb|left|upright|Atomic image (top) and model (bottom) of Nb-doped WS<sub>2</sub>. Blue, red, and yellow spheres indicate W, Nb, and S atoms, respectively. Nb doping allows to reduce the WS<sub>2</sub> bandgap.<ref name=nb>{{cite journal|doi=10.7567/APEX.9.071201|title=Growth and optical properties of Nb-doped WS<sub>2</sub> monolayers|journal=Applied Physics Express|volume=9|issue=7|pages=071201|year=2016|last1=Sasaki|first1=Shogo|last2=Kobayashi|first2=Yu|last3=Liu|first3=Zheng|last4=Suenaga|first4=Kazutomo|last5=Maniwa|first5=Yutaka|last6=Miyauchi|first6=Yuhei|last7=Miyata|first7=Yasumitsu|bibcode=2016APExp...9g1201S|doi-access=free}}{{open access}}</ref>]] |
[[File:WS2-Nb HRTEM2.jpg|thumb|left|upright|Atomic image (top) and model (bottom) of Nb-doped WS<sub>2</sub>. Blue, red, and yellow spheres indicate W, Nb, and S atoms, respectively. Nb doping allows to reduce the WS<sub>2</sub> bandgap.<ref name=nb>{{cite journal|doi=10.7567/APEX.9.071201|title=Growth and optical properties of Nb-doped WS<sub>2</sub> monolayers|journal=Applied Physics Express|volume=9|issue=7|pages=071201|year=2016|last1=Sasaki|first1=Shogo|last2=Kobayashi|first2=Yu|last3=Liu|first3=Zheng|last4=Suenaga|first4=Kazutomo|last5=Maniwa|first5=Yutaka|last6=Miyauchi|first6=Yuhei|last7=Miyata|first7=Yasumitsu|bibcode=2016APExp...9g1201S|doi-access=free}}{{open access}}</ref>]] |
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Bulk WS<sub>2</sub> forms dark gray hexagonal crystals with a layered structure. |
Bulk WS<sub>2</sub> forms dark gray hexagonal crystals with a layered structure. Like the closely related MoS<sub>2</sub>, it exhibits properties of a [[dry lubricant]].<!-- This section needs to be consolidated, as was done with MoS2. |
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We need: |
We need: |
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> Crystalline |
> Crystalline phases section: WS2, just like mos2 can exist in different phases. Recently (2019) the 1T phase has been stabilised. |
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> Allotropes: The beginning paragraph talks of inorganic fullerenes, we should add some more details here. WS2 IFs were the first IFs other than C60! |
> Allotropes: The beginning paragraph talks of inorganic fullerenes, we should add some more details here. WS2 IFs were the first IFs other than C60! |
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Have another section for chemical reactions with acids etc. |
Have another section for chemical reactions with acids etc. |
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Synthesis needs to add: |
Synthesis needs to add: |
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> WS2 was also looked at very early on in scotch tape exfoliation studies of Novoselov and Geim. Should get a mention and |
> WS2 was also looked at very early on in scotch tape exfoliation studies of Novoselov and Geim. Should get a mention and link --> |
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Although it has long been thought that WS<sub>2</sub> is relatively stable in ambient air, recent reports on the ambient air oxidation of monolayer WS<sub>2</sub> have found this to not be the case. In the monolayer form, WS<sub>2</sub> is converted rather rapidly (over the course of days in ambient light and atmosphere) to tungsten oxide via a |
Although it has long been thought that WS<sub>2</sub> is relatively stable in ambient air, recent reports on the ambient air oxidation of monolayer WS<sub>2</sub> have found this to not be the case. In the monolayer form, WS<sub>2</sub> is converted rather rapidly (over the course of days in ambient light and atmosphere) to tungsten oxide via a photo-oxidation reaction involving visible wavelengths of light readily absorbed by monolayer WS<sub>2</sub> (< ~660 nm; > ~1.88 eV).<ref name="Photoxidation_ws2">{{cite journal |last1=Kotsakidis |first1=Jimmy C. |last2=Zhang |first2=Qianhui |last3=Vazquez de Parga |first3=Amadeo L. |last4=Currie |first4=Marc |last5=Helmerson |first5=Kristian |last6=Gaskill |first6=D. Kurt |last7=Fuhrer |first7=Michael S. |title=Oxidation of Monolayer WS2 in Ambient Is a Photoinduced Process |journal=Nano Letters |date=July 2019 |volume=19 |issue=8 |pages=5205–5215 |doi=10.1021/acs.nanolett.9b01599 |pmid=31287707 |arxiv=1906.00375 |bibcode=2019NanoL..19.5205K |s2cid=173990948 }}</ref> In addition to light of suitable wavelength, the reaction likely requires both [[oxygen]] and [[water]] to proceed, with the water thought to act as a [[catalyst]] for oxidation. The products of the reaction likely include various tungsten oxide species and [[sulfuric acid]]. The oxidation of other semiconductor transition metal dichalcogenides (S-TMDs) such as MoS<sub>2</sub>, has similarly been observed to occur in ambient light and atmospheric conditions.<ref name="Mos2_ambient">{{cite journal |last1=Gao |first1=Jian |last2=Li |first2=Baichang |last3=Tan |first3=Jiawei |last4=Chow |first4=Phil |last5=Lu |first5=Toh-Ming |last6=Koratker |first6=Nikhil |title=Aging of Transition Metal Dichalcogenide Monolayers |journal=ACS Nano |date=January 2016 |volume=10 |issue=2 |pages=2628–2635 |doi=10.1021/acsnano.5b07677|pmid=26808328 |s2cid=18010466 }}</ref> |
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WS<sub>2</sub> is also attacked by a mixture of [[nitric acid|nitric]] and [[hydrofluoric acid]]. When heated in oxygen-containing atmosphere, WS<sub>2</sub> converts to [[tungsten trioxide]]. When heated in absence of oxygen, WS<sub>2</sub> does not melt but decomposes to tungsten and sulfur, but only at 1250 °C.<ref name=b1/> |
WS<sub>2</sub> is also attacked by a mixture of [[nitric acid|nitric]] and [[hydrofluoric acid]]. When heated in oxygen-containing atmosphere, WS<sub>2</sub> converts to [[tungsten trioxide]]. When heated in absence of oxygen, WS<sub>2</sub> does not melt but decomposes to tungsten and sulfur, but only at 1250 °C.<ref name=b1/> |
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Historically monolayer WS<sub>2</sub> was isolated using chemical exfoliation via intercalation with lithium from n-butyl lithium (in hexane), followed by exfoliation of the Li intercalated compound by sonication in water.<ref name="n_buli_CE">{{cite journal |last1=Joensen |first1=Per |last2=Frindt |first2=R. F. |last3=Morrison |first3=S. Roy |title=Single-layer MoS2 |journal=Materials Research Bulletin |date=1986 |volume=21 |issue=4 |pages=457–461 |doi=10.1016/0025-5408(86)90011-5 }}</ref> WS<sub>2</sub> also undergoes exfoliation by treatment with various reagents such as [[chlorosulfonic acid]]<ref name="pubs.acs.org"/> and the lithium halides.<ref name="Li_halide">{{cite journal |last1=Ghorai |first1=Aru |last2=Midya |first2=Anupam |last3=Maiti |first3=Rishi |last4=Ray |first4=Samit K. |title=Exfoliation of WS2 in the semiconducting phase using a group of lithium halides: a new method of Li intercalation |journal=Dalton Transactions |date=2016 |volume=45 |issue=38 |pages=14979–14987 |doi=10.1039/C6DT02823C }}</ref> |
Historically monolayer WS<sub>2</sub> was isolated using chemical exfoliation via intercalation with lithium from n-butyl lithium (in hexane), followed by exfoliation of the Li intercalated compound by sonication in water.<ref name="n_buli_CE">{{cite journal |last1=Joensen |first1=Per |last2=Frindt |first2=R. F. |last3=Morrison |first3=S. Roy |title=Single-layer MoS2 |journal=Materials Research Bulletin |date=1986 |volume=21 |issue=4 |pages=457–461 |doi=10.1016/0025-5408(86)90011-5 }}</ref> WS<sub>2</sub> also undergoes exfoliation by treatment with various reagents such as [[chlorosulfonic acid]]<ref name="pubs.acs.org"/> and the lithium halides.<ref name="Li_halide">{{cite journal |last1=Ghorai |first1=Aru |last2=Midya |first2=Anupam |last3=Maiti |first3=Rishi |last4=Ray |first4=Samit K. |title=Exfoliation of WS2 in the semiconducting phase using a group of lithium halides: a new method of Li intercalation |journal=Dalton Transactions |date=2016 |volume=45 |issue=38 |pages=14979–14987 |doi=10.1039/C6DT02823C |pmid=27560159 }}</ref> |
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==Synthesis== |
==Synthesis== |
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WS<sub>2</sub> is produced by a number of methods.<ref name=b1/><ref name="ws2"/> |
WS<sub>2</sub> is produced by a number of methods.<ref name=b1/><ref name="ws2"/> Many of these methods involve treating oxides with sources of sulfide or hydrosulfide, supplied as hydrogen sulfide or generated ''in situ''. |
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===Thin films and monolayers=== |
===Thin films and monolayers=== |
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Widely used techniques for the growth of monolayer WS<sub>2</sub> include [[chemical vapor deposition |
Widely used techniques for the growth of monolayer WS<sub>2</sub> include [[chemical vapor deposition]] (CVD), [[physical vapor deposition]] (PVD) or [[metal organic chemical vapor deposition]] (MOCVD), though most current methods produce sulfur vacancy defects in excess of 1×10<sup>13</sup> cm<sup>−2</sup>.<ref name="DefectDensity">{{cite journal |last1=Hong |first1=Jinhua |last2=Hu |first2=Zhixin |last3=Probert |first3=Matt |last4=Li |first4=Kun |last5=Lv |first5=Danhui |last6=Yang |first6=Xinan |last7=Gu |first7=Lin |last8=Mao |first8=Nannan |last9=Feng |first9=Qingliang |last10=Xie |first10=Liming |last11=Zhang |first11=Jin |last12=Wu |first12=Dianzhong |last13=Zhang |first13=Zhiyong |last14=Jin |first14=Chuanhong |last15=Ji |first15=Wei |last16=Zhang |first16=Xixiang |last17=Yuan |first17=Jun |last18=Zhang |first18=Ze |title=Eploring atomic defects in molybdenum disulphide monolayers |journal=Nature Communications |date=February 2015 |volume=6 |pages=6293 |doi=10.1038/ncomms7293|pmid=25695374 |pmc=4346634 |bibcode=2015NatCo...6.6293H |doi-access=free }}</ref> Other routes entail [[thermal decomposition|thermolysis]] of tungsten(VI) sulfides (e.g., (R<sub>4</sub>N)<sub>2</sub>WS<sub>4</sub>) or the equivalent (e.g., WS<sub>3</sub>).<ref name="ws2"/> |
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Freestanding WS<sub>2</sub> films can be produced as follows. WS<sub>2</sub> is deposited on a hydrophilic substrate, such as [[sapphire]], and then coated with a polymer, such as [[polystyrene]]. After dipping the sample in water for a few minutes, the hydrophobic WS<sub>2</sub> film spontaneously peels off.<ref>{{cite journal|doi=10.1038/srep37833|pmid=27897210|pmc=5126671|title=Fabrication of WS2/GaN p-n Junction by Wafer-Scale WS2 Thin Film Transfer|journal=Scientific Reports|volume=6|pages=37833|year=2016|last1=Yu|first1=Yang|last2=Fong|first2=Patrick W. K.|last3=Wang|first3=Shifeng|last4=Surya|first4=Charles|bibcode=2016NatSR...637833Y}}</ref> |
Freestanding WS<sub>2</sub> films can be produced as follows. WS<sub>2</sub> is deposited on a hydrophilic substrate, such as [[sapphire]], and then coated with a polymer, such as [[polystyrene]]. After dipping the sample in water for a few minutes, the hydrophobic WS<sub>2</sub> film spontaneously peels off.<ref>{{cite journal|doi=10.1038/srep37833|pmid=27897210|pmc=5126671|title=Fabrication of WS2/GaN p-n Junction by Wafer-Scale WS2 Thin Film Transfer|journal=Scientific Reports|volume=6|pages=37833|year=2016|last1=Yu|first1=Yang|last2=Fong|first2=Patrick W. K.|last3=Wang|first3=Shifeng|last4=Surya|first4=Charles|bibcode=2016NatSR...637833Y}}</ref> |
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==Applications== |
==Applications== |
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WS<sub>2</sub> is used, in conjunction with other materials, as [[catalyst]] for [[hydrotreating]] of crude oil.<ref name="ws2"/> |
WS<sub>2</sub> is used, in conjunction with other materials, as [[catalyst]] for [[hydrotreating]] of crude oil.<ref name="ws2"/> In recent years it has also found applications as a saturable for passively mode locked fibre lasers resulting in femtosecond pulses being produced. |
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[[Lamellar]] tungsten |
[[Lamellar]] tungsten disulphide is used as a [[dry lubricant]] for fasteners, bearings, and molds,<ref>{{cite magazine |editor-last1= French |editor-first1= Lester Gray |year= 1967 |title=Dicronite |url=https://books.google.com/books?id=7rYiAQAAMAAJ&q=dicronite |magazine= Machinery |publisher= Machinery Publications Corporation |volume= 73 |page= 101}}</ref> as well as having significant use in aerospace and military industries.<ref>{{Cite web |date=2020-07-07 |title=Quality Approved Special Processes By Special Process Code |publisher=BAE Systems |url=https://www.baesystems.com/en-us/our-company/inc-businesses/electronic-systems/supplier-center}}</ref>{{failed verification|date=August 2020 |reason= article named isn't at this URL; page at this URL doesn't support the following claim}} WS<sub>2</sub> can be applied to a metal surface without binders or curing, via high-velocity [[air impingement]]. The most recent official standard for this process is laid out in the [[SAE International]] specification AMS2530A.<ref>{{Cite web|title=AMS2530A: Tungsten Disulfide Coating, Thin Lubricating Film, Binder-Less Impingement Applied |publisher=SAE International|url=https://www.sae.org/standards/content/ams2530a/|access-date=2020-07-10}}</ref> |
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==Research== |
==Research== |
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Like MoS<sub>2</sub>, nanostructured WS<sub>2</sub> is actively studied for potential applications, such as storage of hydrogen and lithium.<ref name="pubs.acs.org">{{cite journal|doi=10.1021/jz300480w|pmid=26285632|title=Synthesis of Surface-Functionalized WS<sub>2</sub> Nanosheets and Performance as Li-Ion Battery Anodes|journal=The Journal of Physical Chemistry Letters|volume=3|issue=11|pages=1523–30|year=2012|last1=Bhandavat|first1=R.|last2=David|first2=L.|last3=Singh|first3=G.|doi-access=free}}</ref> WS<sub>2</sub> also catalyses [[hydrogenation]] of [[carbon dioxide]]:<ref name="pubs.acs.org"/><ref name=b2/><ref>[https://www.sciencedaily.com/releases/2013/01/130116102018.htm Engineer making rechargeable batteries with layered nanomaterials]. ''Science Daily'' (2013-01-016)</ref> |
Like MoS<sub>2</sub>, nanostructured WS<sub>2</sub> is actively studied for potential applications, such as storage of hydrogen and lithium.<ref name="pubs.acs.org">{{cite journal|doi=10.1021/jz300480w|pmid=26285632|title=Synthesis of Surface-Functionalized WS<sub>2</sub> Nanosheets and Performance as Li-Ion Battery Anodes|journal=The Journal of Physical Chemistry Letters|volume=3|issue=11|pages=1523–30|year=2012|last1=Bhandavat|first1=R.|last2=David|first2=L.|last3=Singh|first3=G.|doi-access=free}}</ref> WS<sub>2</sub> also catalyses [[hydrogenation]] of [[carbon dioxide]]:<ref name="pubs.acs.org"/><ref name=b2/><ref>[https://www.sciencedaily.com/releases/2013/01/130116102018.htm Engineer making rechargeable batteries with layered nanomaterials]. ''Science Daily'' (2013-01-016)</ref> |
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:CO<sub>2</sub> + H<sub>2</sub> |
: CO<sub>2</sub> + H<sub>2</sub> → CO + H<sub>2</sub>O |
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===Nanotubes=== |
===Nanotubes=== |
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<!-- Deleted image removed: [[File:core-shell nanotube.JPG|thumb|Illustration of PbI<sub>2</sub>/WS<sub>2</sub> core–shell nanostructure.]] --> |
<!-- Deleted image removed: [[File:core-shell nanotube.JPG|thumb|Illustration of PbI<sub>2</sub>/WS<sub>2</sub> core–shell nanostructure.]] --> |
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Tungsten disulfide is the first material which was found to form [[ |
Tungsten disulfide is the first material which was found to form [[non-carbon nanotube]]s, in 1992.<ref name=Tenne1992/> This ability is related to the layered structure of WS<sub>2</sub>, and macroscopic amounts of WS<sub>2</sub> have been produced by the methods mentioned above.<ref name="ws2"/> WS<sub>2</sub> nanotubes have been investigated as reinforcing agents to improve the mechanical properties of polymeric nanocomposites. In a study, WS<sub>2</sub> nanotubes reinforced biodegradable polymeric nanocomposites of polypropylene fumarate (PPF) showed significant increases in the Young's modulus, compression yield strength, flexural modulus and flexural yield strength, compared to single- and multi-walled carbon nanotubes reinforced PPF nanocomposites, suggesting that WS<sub>2</sub> nanotubes may be better reinforcing agents than carbon nanotubes.<ref>{{cite journal|last=Lalwani|first=Gaurav|title=Tungsten disulfide nanotubes reinforced biodegradable polymers for bone tissue engineering|journal=Acta Biomaterialia|date=September 2013|volume=9|issue=9|pages=8365–8373|doi=10.1016/j.actbio.2013.05.018|pmid=23727293|pmc=3732565}}</ref> The addition of WS<sub>2</sub> nanotubes to [[epoxy]] resin improved [[adhesion]], [[fracture toughness]] and strain energy release rate. The wear of the nanotubes-reinforced epoxy is lower than that of pure epoxy.<ref name=comp2/> WS<sub>2</sub> nanotubes were embedded into a [[poly(methyl methacrylate)]] (PMMA) nanofiber matrix via electrospinning. The nanotubes were well dispersed and aligned along fiber axis. The enhanced stiffness and toughness of PMMA fiber meshes by means of non-carbon nanotubes addition may have potential uses as impact-absorbing materials, e.g. for [[ballistic vest]]s.<ref name=comp3/><ref>[http://www.physorg.com/news8947.html Nano-Armor: Protecting the Soldiers of Tomorrow]. Physorg.com (2005-12-10). Retrieved on 2016-01-20</ref> |
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WS<sub>2</sub> nanotubes are hollow and can be filled with another material, to preserve or guide it to a desired location, or to generate new properties in the filler material which is confined within a nanometer-scale diameter. To this goal, |
WS<sub>2</sub> nanotubes are hollow and can be filled with another material, to preserve or guide it to a desired location, or to generate new properties in the filler material which is confined within a nanometer-scale diameter. To this goal, non-carbon nanotube hybrids were made by filling WS<sub>2</sub> nanotubes with molten lead, antimony or bismuth iodide salt by a capillary wetting process, resulting in PbI<sub>2</sub>@WS<sub>2</sub>, SbI<sub>3</sub>@WS<sub>2</sub> or BiI<sub>3</sub>@WS<sub>2</sub> core–shell nanotubes.<ref name=shell/> |
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===Nanosheets=== |
===Nanosheets=== |
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{{see also|Transition metal dichalcogenide monolayers}} |
{{see also|Transition metal dichalcogenide monolayers}} |
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WS<sub>2</sub> can also exist in the form of atomically thin sheets.<ref>{{cite journal|doi=10.1126/science.1194975 |pmid=21292974 |title=Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials|bibcode=2011Sci...331..568C|url=https://www.researchgate.net/publication/49809453 |journal=Science |volume=331 |issue=6017 |pages=568–71 |year=2011 |last1=Coleman |first1=J. N. |last2=Lotya |first2=M. |last3=O'Neill |first3=A. |last4=Bergin |first4=S. D. |last5=King |first5=P. J. |last6=Khan |first6=U. |last7=Young |first7=K. |last8=Gaucher |first8=A. |last9=De |first9=S. |last10=Smith |first10=R. J. |last11=Shvets |first11=I. V. |last12=Arora |first12=S. K. |last13=Stanton |first13=G. |last14=Kim |first14=H.-Y. |last15=Lee |first15=K. |last16=Kim |first16=G. T. |last17=Duesberg |first17=G. S. |last18=Hallam |first18=T. |last19=Boland |first19=J. J. |last20=Wang |first20=J. J. |last21=Donegan |first21=J. F. |last22=Grunlan |first22=J. C. |last23=Moriarty |first23=G. |last24=Shmeliov |first24=A. |last25=Nicholls |first25=R. J. |last26=Perkins |first26=J. M. |last27=Grieveson |first27=E. M. |last28=Theuwissen |first28=K. |last29=McComb |first29=D. W. |last30=Nellist |first30=P. D. |
WS<sub>2</sub> can also exist in the form of atomically thin sheets.<ref>{{cite journal|doi=10.1126/science.1194975 |pmid=21292974 |title=Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials|bibcode=2011Sci...331..568C|url=https://www.researchgate.net/publication/49809453 |journal=Science |volume=331 |issue=6017 |pages=568–71 |year=2011 |last1=Coleman |first1=J. N. |last2=Lotya |first2=M. |last3=O'Neill |first3=A. |last4=Bergin |first4=S. D. |last5=King |first5=P. J. |last6=Khan |first6=U. |last7=Young |first7=K. |last8=Gaucher |first8=A. |last9=De |first9=S. |last10=Smith |first10=R. J. |last11=Shvets |first11=I. V. |last12=Arora |first12=S. K. |last13=Stanton |first13=G. |last14=Kim |first14=H.-Y. |last15=Lee |first15=K. |last16=Kim |first16=G. T. |last17=Duesberg |first17=G. S. |last18=Hallam |first18=T. |last19=Boland |first19=J. J. |last20=Wang |first20=J. J. |last21=Donegan |first21=J. F. |last22=Grunlan |first22=J. C. |last23=Moriarty |first23=G. |last24=Shmeliov |first24=A. |last25=Nicholls |first25=R. J. |last26=Perkins |first26=J. M. |last27=Grieveson |first27=E. M. |last28=Theuwissen |first28=K. |last29=McComb |first29=D. W. |last30=Nellist |first30=P. D. |hdl=2262/66458 |s2cid=23576676 |hdl-access=free }}</ref> Such materials exhibit room-temperature photoluminescence in the monolayer limit.<ref name="ReferenceA">{{cite journal|doi=10.1021/nl3026357|pmid=23194096|title=Extraordinary Room-Temperature Photoluminescence in Triangular WS<sub>2</sub> Monolayers|journal=Nano Letters|volume=13|issue=8|pages=3447–54|year=2013|last1=Gutiérrez|first1=Humberto R.|last2=Perea-López|first2=Nestor|last3=Elías|first3=Ana Laura|last4=Berkdemir|first4=Ayse|last5=Wang|first5=Bei|last6=Lv|first6=Ruitao|last7=López-Urías|first7=Florentino|last8=Crespi|first8=Vincent H.|last9=Terrones|first9=Humberto|last10=Terrones|first10=Mauricio|arxiv=1208.1325|bibcode=2013NanoL..13.3447G|s2cid=207597527 }}</ref> |
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===Transistors=== |
===Transistors=== |
||
[[Taiwan Semiconductor Manufacturing Company]] (TSMC) is investigating use of {{Chem|W|S|2}} as a channel material in [[field effect transistor]]s. The approximately 6-layer thick material is created using [[chemical vapor deposition]] (CVD).<ref name="ChengChung2019">{{cite book|last1=Cheng|first1=Chao-Ching|title=2019 Symposium on VLSI Technology|last2=Chung|first2=Yun-Yan|last3=Li|first3=Uing-Yang|last4=Lin|first4=Chao-Ting|last5=Li|first5=Chi-Feng|last6=Chen|first6=Jyun-Hong|last7=Lai|first7=Tung-Yen|last8=Li|first8=Kai-Shin|last9=Shieh|first9=Jia-Min|last10=Su|first10=Sheng-Kai|last11=Chiang|first11=Hung-Li|last12=Chen|first12=Tzu-Chiang|last13=Li|first13=Lain-Jong|last14=Wong|first14=H.-S. Philip|last15=Chien|first15=Chao-Hsin|chapter=First demonstration of 40-nm channel length top-gate WS2 pFET using channel area-selective CVD growth directly on SiOx/Si substrate|year=2019|pages=T244–T245|doi=10.23919/VLSIT.2019.8776498|publisher=[[IEEE]]|isbn=978-4-86348-719-2}}</ref> |
[[Taiwan Semiconductor Manufacturing Company]] (TSMC) is investigating use of {{Chem|W|S|2}} as a channel material in [[field effect transistor]]s. The approximately 6-layer thick material is created using [[chemical vapor deposition]] (CVD).<ref name="ChengChung2019">{{cite book|last1=Cheng|first1=Chao-Ching|title=2019 Symposium on VLSI Technology|last2=Chung|first2=Yun-Yan|last3=Li|first3=Uing-Yang|last4=Lin|first4=Chao-Ting|last5=Li|first5=Chi-Feng|last6=Chen|first6=Jyun-Hong|last7=Lai|first7=Tung-Yen|last8=Li|first8=Kai-Shin|last9=Shieh|first9=Jia-Min|last10=Su|first10=Sheng-Kai|last11=Chiang|first11=Hung-Li|last12=Chen|first12=Tzu-Chiang|last13=Li|first13=Lain-Jong|last14=Wong|first14=H.-S. Philip|last15=Chien|first15=Chao-Hsin|chapter=First demonstration of 40-nm channel length top-gate WS2 pFET using channel area-selective CVD growth directly on SiOx/Si substrate|year=2019|pages=T244–T245|doi=10.23919/VLSIT.2019.8776498|publisher=[[IEEE]]|isbn=978-4-86348-719-2|s2cid=198931613 }}</ref> |
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==References== |
==References== |
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{{reflist|refs= |
{{reflist|refs= |
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<ref name=b1>{{cite book|author=Eagleson, Mary |title=Concise encyclopedia chemistry|url=https://books.google.com/books?id=Owuv-c9L_IMC&pg=PA1129|year=1994|publisher=Walter de Gruyter|isbn=978-3-11-011451-5|page=1129}}</ref> |
<ref name=b1>{{cite book |author=Eagleson, Mary |title=Concise encyclopedia chemistry |url=https://books.google.com/books?id=Owuv-c9L_IMC&pg=PA1129 |year=1994 |publisher=Walter de Gruyter |isbn=978-3-11-011451-5 |page=1129}}</ref> |
||
<ref name=b2>{{cite book|author1=Lassner, Erik |author2=Schubert, Wolf-Dieter |title=Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds|url=https://books.google.com/books?id=foLRISkt9gcC&pg=PA374|year=1999|publisher=Springer|isbn=978-0-306-45053-2|pages=374–}}</ref> |
<ref name=b2>{{cite book |author1=Lassner, Erik |author2=Schubert, Wolf-Dieter |title=Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds |url=https://books.google.com/books?id=foLRISkt9gcC&pg=PA374 |year=1999 |publisher=Springer |isbn=978-0-306-45053-2 |pages=374–}}</ref> |
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<ref name=Tenne1992>{{cite journal |vauthors=Tenne R, Margulis L, Genut M, Hodes G |year |
<ref name=Tenne1992>{{cite journal |vauthors=Tenne R, Margulis L, Genut M, Hodes G |year=1992 |title=Polyhedral and cylindrical structures of tungsten disulphide |bibcode=1992Natur.360..444T |journal=Nature |volume=360 |issue=6403 |pages=444–446 |doi=10.1038/360444a0|s2cid=4309310 }}</ref> |
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<ref name="ws2">{{cite journal |author1=Panigrahi, Pravas Kumar |author2=Pathak, Amita | |
<ref name="ws2">{{cite journal |author1=Panigrahi, Pravas Kumar |author2=Pathak, Amita |journal=Sci. Technol. Adv. Mater. |title=Microwave-assisted synthesis of WS<sub>2</sub> nanowires through tetrathiotungstate precursors |format=free download |volume=9 |year=2008 |page=045008 |doi=10.1088/1468-6996/9/4/045008 |issue=4 |pmc=5099650 |bibcode=2008STAdM...9d5008P |pmid=27878036}}</ref> |
||
<ref name=comp2>{{cite journal|author=Zohar, E.|title= |
<ref name=comp2>{{cite journal |author=Zohar, E. |title=The Mechanical and Tribological Properties of Epoxy Nanocomposites with WS<sub>2</sub> Nanotubes |journal=Sensors & Transducers Journal |volume=12 |issue=Special Issue |year=2011 |pages=53–65 |url=http://www.sensorsportal.com/HTML/DIGEST/P_SI_159.htm |display-authors=etal}}</ref> |
||
<ref name=comp3>{{cite journal|author1=Reddy, C. S. |author2=Zak, A. |author3=Zussman, E. |
<ref name=comp3>{{cite journal |author1=Reddy, C. S. |author2=Zak, A. |author3=Zussman, E. |title=WS<sub>2</sub> nanotubes embedded in PMMA nanofibers as energy absorptive material |journal=J. Mater. Chem. |year=2011 |volume=21 |pages=16086–16093 |doi=10.1039/C1JM12700D |issue=40}}</ref> |
||
<ref name=shell>{{cite journal|title= Synthesis of Core-Shell Inorganic Nanotubes|journal= |
<ref name=shell>{{cite journal |title= Synthesis of Core-Shell Inorganic Nanotubes |journal=Adv. Funct. Mater. |year=2010 |volume=20 |pages=2459–2468 |doi=10.1002/adfm.201000490 |issue=15 |last1=Kreizman |first1=Ronen |last2=Enyashin |first2=Andrey N. |last3=Deepak |first3=Francis Leonard |last4=Albu-Yaron |first4=Ana |last5=Popovitz-Biro |first5=Ronit |last6=Seifert |first6=Gotthard |last7=Tenne |first7=Reshef|s2cid=136725896 }}</ref> |
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}} |
}} |
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[[Category:Tungsten compounds]] |
[[Category:Tungsten compounds]] |
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[[Category: |
[[Category:Disulfides]] |
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[[Category:Dry lubricants]] |
[[Category:Dry lubricants]] |
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[[Category:Transition metal dichalcogenides]] |
[[Category:Transition metal dichalcogenides]] |
Left: WS2 film on sapphire. Right: dark exfoliated WS2 film floating on water | |
Names | |
---|---|
IUPAC names
Tungsten sulfur | |
Systematic IUPAC name
Dithioxotungsten | |
Other names
Tungsten(IV) sulfide | |
Identifiers | |
3D model (JSmol) |
|
ChEBI | |
ChemSpider |
|
ECHA InfoCard | 100.032.027 |
EC Number |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| |
| |
Properties | |
WS2 | |
Molar mass | 247.98 g/mol |
Appearance | Blue-gray powder[1] |
Density | 7.5 g/cm3, solid[1] |
Melting point | 1,250 °C (2,280 °F; 1,520 K) decomposes[1] |
Slightly soluble | |
Band gap | ~1.35 eV (optical, indirect, bulk)[2][3] ~2.05 eV (optical, direct, monolayer)[4] |
+5850·10−6 cm3/mol[5] | |
Structure | |
Molybdenite | |
Trigonal prismatic (WIV) Pyramidal (S2−) | |
Related compounds | |
Other anions |
Tungsten(IV) oxide Tungsten diselenide Tungsten ditelluride |
Other cations |
Molybdenum disulfide Tantalum disulfide Rhenium disulfide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Tungsten disulfide is an inorganic chemical compound composed of tungsten and sulfur with the chemical formula WS2. This compound is part of the group of materials called the transition metal dichalcogenides. It occurs naturally as the rare mineral tungstenite. This material is a component of certain catalysts used for hydrodesulfurization and hydrodenitrification.
WS2 adopts a layered structure similar, or isotypic with MoS2, instead with W atoms situated in trigonal prismatic coordination sphere (in place of Mo atoms). Owing to this layered structure, WS2 forms non-carbon nanotubes, which were discovered after heating a thin sample of WS2 in 1992.[6]
Bulk WS2 forms dark gray hexagonal crystals with a layered structure. Like the closely related MoS2, it exhibits properties of a dry lubricant.
Although it has long been thought that WS2 is relatively stable in ambient air, recent reports on the ambient air oxidation of monolayer WS2 have found this to not be the case. In the monolayer form, WS2 is converted rather rapidly (over the course of days in ambient light and atmosphere) to tungsten oxide via a photo-oxidation reaction involving visible wavelengths of light readily absorbed by monolayer WS2 (< ~660 nm; > ~1.88 eV).[8] In addition to light of suitable wavelength, the reaction likely requires both oxygen and water to proceed, with the water thought to act as a catalyst for oxidation. The products of the reaction likely include various tungsten oxide species and sulfuric acid. The oxidation of other semiconductor transition metal dichalcogenides (S-TMDs) such as MoS2, has similarly been observed to occur in ambient light and atmospheric conditions.[9]
WS2 is also attacked by a mixture of nitric and hydrofluoric acid. When heated in oxygen-containing atmosphere, WS2 converts to tungsten trioxide. When heated in absence of oxygen, WS2 does not melt but decomposes to tungsten and sulfur, but only at 1250 °C.[1]
Historically monolayer WS2 was isolated using chemical exfoliation via intercalation with lithium from n-butyl lithium (in hexane), followed by exfoliation of the Li intercalated compound by sonication in water.[10]WS2 also undergoes exfoliation by treatment with various reagents such as chlorosulfonic acid[11] and the lithium halides.[12]
WS2 is produced by a number of methods.[1][13] Many of these methods involve treating oxides with sources of sulfide or hydrosulfide, supplied as hydrogen sulfide or generated in situ.
Widely used techniques for the growth of monolayer WS2 include chemical vapor deposition (CVD), physical vapor deposition (PVD) or metal organic chemical vapor deposition (MOCVD), though most current methods produce sulfur vacancy defects in excess of 1×1013 cm−2.[14] Other routes entail thermolysis of tungsten(VI) sulfides (e.g., (R4N)2WS4) or the equivalent (e.g., WS3).[13]
Freestanding WS2 films can be produced as follows. WS2 is deposited on a hydrophilic substrate, such as sapphire, and then coated with a polymer, such as polystyrene. After dipping the sample in water for a few minutes, the hydrophobic WS2 film spontaneously peels off.[15]
WS2 is used, in conjunction with other materials, as catalyst for hydrotreating of crude oil.[13] In recent years it has also found applications as a saturable for passively mode locked fibre lasers resulting in femtosecond pulses being produced.
Lamellar tungsten disulphide is used as a dry lubricant for fasteners, bearings, and molds,[16] as well as having significant use in aerospace and military industries.[17][failed verification]WS2 can be applied to a metal surface without binders or curing, via high-velocity air impingement. The most recent official standard for this process is laid out in the SAE International specification AMS2530A.[18]
Like MoS2, nanostructured WS2 is actively studied for potential applications, such as storage of hydrogen and lithium.[11]WS2 also catalyses hydrogenationofcarbon dioxide:[11][19][20]
Tungsten disulfide is the first material which was found to form non-carbon nanotubes, in 1992.[6] This ability is related to the layered structure of WS2, and macroscopic amounts of WS2 have been produced by the methods mentioned above.[13]WS2 nanotubes have been investigated as reinforcing agents to improve the mechanical properties of polymeric nanocomposites. In a study, WS2 nanotubes reinforced biodegradable polymeric nanocomposites of polypropylene fumarate (PPF) showed significant increases in the Young's modulus, compression yield strength, flexural modulus and flexural yield strength, compared to single- and multi-walled carbon nanotubes reinforced PPF nanocomposites, suggesting that WS2 nanotubes may be better reinforcing agents than carbon nanotubes.[21] The addition of WS2 nanotubes to epoxy resin improved adhesion, fracture toughness and strain energy release rate. The wear of the nanotubes-reinforced epoxy is lower than that of pure epoxy.[22]WS2 nanotubes were embedded into a poly(methyl methacrylate) (PMMA) nanofiber matrix via electrospinning. The nanotubes were well dispersed and aligned along fiber axis. The enhanced stiffness and toughness of PMMA fiber meshes by means of non-carbon nanotubes addition may have potential uses as impact-absorbing materials, e.g. for ballistic vests.[23][24]
WS2 nanotubes are hollow and can be filled with another material, to preserve or guide it to a desired location, or to generate new properties in the filler material which is confined within a nanometer-scale diameter. To this goal, non-carbon nanotube hybrids were made by filling WS2 nanotubes with molten lead, antimony or bismuth iodide salt by a capillary wetting process, resulting in PbI2@WS2, SbI3@WS2 or BiI3@WS2 core–shell nanotubes.[25]
WS2 can also exist in the form of atomically thin sheets.[26] Such materials exhibit room-temperature photoluminescence in the monolayer limit.[27]
Taiwan Semiconductor Manufacturing Company (TSMC) is investigating use of WS
2 as a channel material in field effect transistors. The approximately 6-layer thick material is created using chemical vapor deposition (CVD).[28]
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Tungsten(III) |
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Tungsten(IV) |
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Tungsten(V) |
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Tungsten(VI) |
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Sulfides (S2−)
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