Melting - Wikipedia

Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy ... Melting FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Materialphasechange FortheEPbyHyuna,seeMelting(EP).ForthealbumbyMamamoo,seeMelting(album). "Molten"redirectshere.Forotheruses,seeMolten(disambiguation). Meltingicecubesillustratetheprocessoffusion. Melting,orfusion,isaphysicalprocessthatresultsinthephasetransitionofasubstancefromasolidtoaliquid.Thisoccurswhentheinternalenergyofthesolidincreases,typicallybytheapplicationofheatorpressure,whichincreasesthesubstance'stemperaturetothemeltingpoint.Atthemeltingpoint,theorderingofionsormoleculesinthesolidbreaksdowntoalessorderedstate,andthesolid"melts"tobecomealiquid. Substancesinthemoltenstategenerallyhavereducedviscosityasthetemperatureincreases.Anexceptiontothisprincipleistheelementsulfur,whoseviscosityincreasesintherangeof160 °Cto180 °Cduetopolymerization.[1] Someorganiccompoundsmeltthroughmesophases,statesofpartialorderbetweensolidandliquid. Contents 1Firstorderphasetransition 2Criteria 3Supercooling 4Glasses 5Relatedconcept 6Table 7Seealso 8References 9Externallinks Firstorderphasetransition[edit] Fromathermodynamicspointofview,atthemeltingpointthechangeinGibbsfreeenergy∆Gofthesubstancesiszero,buttherearenon-zerochangesintheenthalpy(H)andtheentropy(S),knownrespectivelyastheenthalpyoffusion(orlatentheatoffusion)andtheentropyoffusion.Meltingisthereforeclassifiedasafirst-orderphasetransition.MeltingoccurswhentheGibbsfreeenergyoftheliquidbecomeslowerthanthesolidforthatmaterial.[2][3]Thetemperatureatwhichthisoccursisdependentontheambientpressure. Low-temperatureheliumistheonlyknownexceptiontothegeneralrule.[4]Helium-3hasanegativeenthalpyoffusionattemperaturesbelow0.3K.Helium-4alsohasaveryslightlynegativeenthalpyoffusionbelow0.8K.Thismeansthat,atappropriateconstantpressures,heatmustberemovedfromthesesubstancesinordertomeltthem.[5] Criteria[edit] Amongthetheoreticalcriteriaformelting,theLindemann[6]andBorn[7]criteriaarethosemostfrequentlyusedasabasistoanalysethemeltingconditions. TheLindemanncriterionstatesthatmeltingoccursbecauseof"vibrationalinstability",e.g.crystalsmelt;whentheaverageamplitudeofthermalvibrationsofatomsisrelativelyhighcomparedwithinteratomicdistances,e.g.1/2>δLRs,whereδuistheatomicdisplacement,theLindemannparameterδL≈0.20...0.25andRsisone-halfoftheinter-atomicdistance.[8]: 177 The"Lindemannmeltingcriterion"issupportedbyexperimentaldatabothforcrystallinematerialsandforglass-liquidtransitionsinamorphousmaterials. TheBorncriterionisbasedonarigiditycatastrophecausedbythevanishingelasticshearmodulus,i.e.whenthecrystalnolongerhassufficientrigiditytomechanicallywithstandtheload,itbecomesliquid.[9] Supercooling[edit] Mainarticle:Supercooling Underastandardsetofconditions,themeltingpointofasubstanceisacharacteristicproperty.Themeltingpointisoftenequaltothefreezingpoint.However,undercarefullycreatedconditions,supercooling,orsuperheatingpastthemeltingorfreezingpointcanoccur.Wateronaverycleanglasssurfacewilloftensupercoolseveraldegreesbelowthefreezingpointwithoutfreezing.Fineemulsionsofpurewaterhavebeencooledto−38 °Cwithoutnucleationtoformice.[citationneeded]Nucleationoccursduetofluctuationsinthepropertiesofthematerial.[citationneeded]Ifthematerialiskeptstillthereisoftennothing(suchasphysicalvibration)totriggerthischange,andsupercooling(orsuperheating)mayoccur.Thermodynamically,thesupercooledliquidisinthemetastablestatewithrespecttothecrystallinephase,anditislikelytocrystallizesuddenly. Glasses[edit] Glassesareamorphoussolids,whichareusuallyfabricatedwhenthemoltenmaterialcoolsveryrapidlytobelowitsglasstransitiontemperature,withoutsufficienttimeforaregularcrystallatticetoform.Solidsarecharacterisedbyahighdegreeofconnectivitybetweentheirmolecules,andfluidshavelowerconnectivityoftheirstructuralblocks.Meltingofasolidmaterialcanalsobeconsideredasapercolationviabrokenconnectionsbetweenparticlese.g.connectingbonds.[10]Inthisapproachmeltingofanamorphousmaterialoccurs,whenthebrokenbondsformapercolationclusterwithTgdependentonquasi-equilibriumthermodynamicparametersofbondse.g.onenthalpy(Hd)andentropy(Sd)offormationofbondsinagivensystematgivenconditions:[11] T g = H d S d + R ln ⁡ ( 1 − f c f c ) , {\displaystyleT_{g}={\frac{H_{d}}{S_{d}+R\ln({\frac{1-f_{c}}{f_{c}}})}},} wherefcisthepercolationthresholdandRistheuniversalgasconstant. AlthoughHdandSdarenottrueequilibriumthermodynamicparametersandcandependonthecoolingrateofamelt,theycanbefoundfromavailableexperimentaldataonviscosityofamorphousmaterials. Evenbelowitsmeltingpoint,quasi-liquidfilmscanbeobservedoncrystallinesurfaces.Thethicknessofthefilmistemperature-dependent.Thiseffectiscommonforallcrystallinematerials.Pre-meltingshowsitseffectsine.g.frostheave,thegrowthofsnowflakes,and,takinggrainboundaryinterfacesintoaccount,maybeeveninthemovementofglaciers. Relatedconcept[edit] Inultrashortpulsephysics,aso-callednonthermalmeltingmaytakeplace.Itoccursnotbecauseoftheincreaseoftheatomickineticenergy,butbecauseofchangesoftheinteratomicpotentialduetoexcitationofelectrons.Sinceelectronsareactinglikeagluestickingatomstogether,heatingelectronsbyafemtosecondlaseraltersthepropertiesofthis"glue",whichmaybreakthebondsbetweentheatomsandmeltamaterialevenwithoutanincreaseoftheatomictemperature.[12] Ingenetics,meltingDNAmeanstoseparatethedouble-strandedDNAintotwosinglestrandsbyheatingortheuseofchemicalagents,polymerasechainreaction. Table[edit] Phasetransitionsofmatter(vte) ToFrom Solid Liquid Gas Plasma Solid Melting Sublimation Liquid Freezing Vaporization Gas Deposition Condensation Ionization Plasma Recombination Seealso[edit] Listofchemicalelementsprovidingmeltingpoints Phasediagram Zonemelting References[edit] ^Sofekun,GabrielO.;Evoy,Erin;Lesage,KevinL.;Chou,Nancy;Marriott,RobertA.(2018)."Therheologyofliquidelementalsulfuracrosstheλ-transition".JournalofRheology.SocietyofRheology.62(2):469–476.Bibcode:2018JRheo..62..469S.doi:10.1122/1.5001523.ISSN 0148-6055. ^Atkins,P.W.(PeterWilliam),1940-author.(2017).Elementsofphysicalchemistry.ISBN 978-0-19-879670-1.OCLC 982685277.{{citebook}}:|last=hasgenericname(help)CS1maint:multiplenames:authorslist(link) ^Pedersen,UlfR.;Costigliola,Lorenzo;Bailey,NicholasP.;Schrøder,ThomasB.;Dyre,JeppeC.(2016)."Thermodynamicsoffreezingandmelting".NatureCommunications.7(1):12386.Bibcode:2016NatCo...712386P.doi:10.1038/ncomms12386.ISSN 2041-1723.PMC 4992064.PMID 27530064. ^Atkins,Peter;Jones,Loretta(2008),ChemicalPrinciples:TheQuestforInsight(4th ed.),W.H.FreemanandCompany,p. 236,ISBN 978-0-7167-7355-9 ^Ott,J.Bevan;Boerio-Goates,Juliana(2000),ChemicalThermodynamics:AdvancedApplications,AcademicPress,pp. 92–93,ISBN 978-0-12-530985-1 ^Lindemann,F.A.(1910)."ÜberdieBerechnungmolekularerEigenfrequenzen".PhysikalischeZeitschrift(inGerman).11(14):609–614. ^Born,Max(1939)."ThermodynamicsofCrystalsandMelting".TheJournalofChemicalPhysics.AIPPublishing.7(8):591–603.Bibcode:1939JChPh...7..591B.doi:10.1063/1.1750497.ISSN 0021-9606. ^StuartA.Rice(15February2008).AdvancesinChemicalPhysics.JohnWiley&Sons.ISBN 978-0-470-23807-3. ^RobertW.Cahn(2001)Materialsscience:MeltingfromWithin,Nature413(#6856) ^Park,SungYong;Stroud,D.(11June2003)."Theoryofmeltingandtheopticalpropertiesofgold/DNAnanocomposites".PhysicalReviewB.AmericanPhysicalSociety(APS).67(21):212202.arXiv:cond-mat/0305230.Bibcode:2003PhRvB..67u2202P.doi:10.1103/physrevb.67.212202.ISSN 0163-1829.S2CID 14718724. ^Ojovan,MichaelI;Lee,William(Bill)E(2010)."Connectivityandglasstransitionindisorderedoxidesystems".JournalofNon-CrystallineSolids.ElsevierBV.356(44–49):2534–2540.Bibcode:2010JNCS..356.2534O.doi:10.1016/j.jnoncrysol.2010.05.012.ISSN 0022-3093. ^Medvedev,Nikita;Li,Zheng;Ziaja,Beata(2015)."Thermalandnonthermalmeltingofsiliconunderfemtosecondx-rayirradiation".PhysicalReviewB.91(5):054113.arXiv:1504.05053.Bibcode:2015PhRvB..91e4113M.doi:10.1103/PhysRevB.91.054113.S2CID 49258288. Externallinks[edit] ThedictionarydefinitionofmeltingatWiktionary vteStatesofmatter(list)State Solid Liquid Gas/Vapor Plasma Lowenergy Bose–Einsteincondensate Fermioniccondensate Degeneratematter QuantumHall Rydbergmatter Rydbergpolaron Strangematter Superfluid Supersolid Photonicmolecule Highenergy QCDmatter LatticeQCD Quark–gluonplasma Color-glasscondensate Supercriticalfluid Otherstates Colloid Glass Crystal Liquidcrystal Timecrystal Quantumspinliquid Exoticmatter Programmablematter Darkmatter Antimatter Magneticallyordered Antiferromagnet Ferrimagnet Ferromagnet String-netliquid Superglass Transitions Boiling Boilingpoint Condensation Criticalline Criticalpoint Crystallization Deposition Evaporation Flashevaporation Freezing Chemicalionization Ionization Lambdapoint Melting Meltingpoint Recombination Regelation Saturatedfluid Sublimation Supercooling Triplepoint Vaporization Vitrification Quantities Enthalpyoffusion Enthalpyofsublimation Enthalpyofvaporization Latentheat Latentinternalenergy Trouton'srule Volatility Concepts Baryonicmatter Binodal Compressedfluid Coolingcurve Equationofstate Leidenfrosteffect Macroscopicquantumphenomena Mpembaeffect Orderanddisorder(physics) Spinodal Superconductivity Superheatedvapor Superheating Thermo-dielectriceffect Authoritycontrol:Nationallibraries France(data) Israel UnitedStates Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Melting&oldid=1099062595" Categories:PhasetransitionsMaterialsscienceThermodynamicsHiddencategories:CS1errors:genericnameCS1maint:multiplenames:authorslistCS1German-languagesources(de)ArticleswithshortdescriptionShortdescriptionisdifferentfromWikidataAllarticleswithunsourcedstatementsArticleswithunsourcedstatementsfromApril2008ArticleswithBNFidentifiersArticleswithJ9UidentifiersArticleswithLCCNidentifiers Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English Views ReadEditViewhistory More Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Inotherprojects WikimediaCommons Languages العربيةAvañe'ẽBân-lâm-gúБеларускаяBikolCentralБългарскиCatalàЧӑвашлаČeštinaChiShonaDanskDeutschEestiΕλληνικάЭрзяньEspañolEuskaraفارسیFrançaisGalego한국어Հայերենहिन्दीHrvatskiBahasaIndonesiaItalianoעבריתಕನ್ನಡҚазақшаKiswahiliLatinaLatviešuLietuviųMagyarМакедонскиമലയാളംBahasaMelayuMìng-dĕ̤ng-ngṳ̄Nederlands日本語NorskbokmålNorsknynorskOccitanOʻzbekcha/ўзбекчаPiemontèisPlattdüütschPolskiPortuguêsRomânăРусскийSimpleEnglishSlovenčinaSlovenščinaکوردیСрпски/srpskiSrpskohrvatski/српскохрватскиSuomiSvenskaதமிழ்ไทยТоҷикӣTürkçeУкраїнськаTiếngViệtWinaray吴语粵語中文 Editlinks