General theory of multi-phase melt crystallization.pdf

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1、JournalofCrystalGrowth234(2002)762–772Generaltheoryofmulti-phasemeltcrystallizationabb,N.A.Charykov,V.V.Sherstnev,A.Krier*aSt.PetersburgStateTechnologicalInstitute(TechnicalUniversity),St.Petersburg,198013RussiabPhysicsDepartment,SchoolofPhysicsandCh

2、emistry,Adv.MaterialsandPhotonicsGroup,LancasterUniversity,LancasterLA14YB,UKReceived1December2000;accepted22September2001CommunicatedbyD.T.J.HurleAbstractAnewapproachispresentedwhichhaswide-rangingapplicationforthemodelingandunderstandingofbothopenm

3、ulti-phasecrystallizationfromthemeltwhilethetemperatureisdecreasing,andisothermalcrystallizationfromsolutionwhilesolventisevaporating.Theresultsarewidelyapplicable.Examplesaregivenwhichrelatetolaboratorysituationssuchastheliquid-phaseepitaxialgrowtho

4、fcomplexIII–Valloysandalsotocrystallizationprocessesinoceansorseawater.r2002ElsevierScienceB.V.Allrightsreserved.Keywords:A2.Growthfrommelt;A2.Growthfromsolution1.Opencrystallizationfrommulti-componentmeltsDiagramsofopencrystallizationfrommulti-compo

5、nentmeltswhilethetemperatureisincreasingordecreasingaremoreinterestingfortechnologyandmodelingofnaturalprocessesthanphaseequilibriumdiagrams.Consequently,thethermodynamicsofsuchphaseprocesses(andprocessesofopenevaporation)havebeenelaboratedindetailfo

6、rsolidphaseswithinvariable(componentsandcompounds)andvariable(solidsolutions)compositions(seeforexampleRefs.[1–5]).Butintheseworksthephaseequilibriumofonlytwophases(meltandsolid)hasbeenconsidered.Atpresent,thereisnocomprehensivethermodynamictheory,wh

7、ichdescribesthecrystallizationprocessesofanarbitrarynumberofsolidphases(kX1)withinvariableandvariablecompositionswithintheconditionsofmulti-variantequilibrium(numberofthermodynamicdegreesoffreedomfX1).Thisisbecausemulti-variantcrystallizationtakespla

8、ceonlyinsystemswithalargenumberofcomponentsnX4;buttilldatethesesystemshavebeeninsufficientlystudied(i.e.ifn¼3crystallizationoftwosolidphasesonlycausesthemovementofmeltcompositionalongthemono-variantcrystallizationcurvecorrespondingtof¼1;andsuchaconside