V.M. Sglavo – GlassEng - UNITN 2017 Free energy of mixture ... ?· V.M. Sglavo – GlassEng - UNITN…

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<p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>Phaseseparationinglass</p> <p>Free energy of mixture: Gm = Hm - T Sm</p> <p>entropy-Sm</p> <p>entalpy-Hm</p> <p>Termodinamica strutturale, J.H. Brophy, R.M. Rose, J. Wulff,, Ambrosiana Ed., 1975</p> <p>A,Baf3ine idealsituation A,Bnotaf3ine</p> <p>Halloy</p> <p>Halloy</p> <p>Halloy</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>freeenergy-Gm</p> <p>completemiscibilityinonesinglephase</p> <p>incompletemiscibilitytwophases</p> <p>Termodinamica strutturale, J.H. Brophy, R.M. Rose, J. Wulff,, Ambrosiana Ed., 1975</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>G(c)= G(c0)+ Gc c0(c c0)+ 12</p> <p>2Gc2 c0</p> <p>(c c0)2 + .....</p> <p>Ifc=c0-c0</p> <p>G TC: complete miscibilityT &lt; TC: immiscibility</p> <p>spinode</p> <p>unstablezone</p> <p>metastablezones</p> <p>Separationmechanisms:- nucleationandgrowth(metastablezone)largevariationofG</p> <p>- spinodaldecomposition(unstablezone)gradualvariationofcomposition(spontaneous)</p> <p>Struttura e genesi dello stato vetroso, A. Maddalena, Cleup, 1983</p> <p>TEMPERATURE</p> <p>FREEENERGY</p> <p>COMPOSITION</p> <p>composition</p> <p>distance</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>nucleationandgrowthspinodaldecomposition</p> <p>interconnectedstructure islesstructure</p> <p>Introduction to glass science and technology, J. E. Shelby, The Royal Society of Chemistry, 1997</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>stableimmiscibility metastableimmiscibility</p> <p>Immiscibility diagrams</p> <p>Tg</p> <p>Introduction to glass science and technology, J. E. Shelby, The Royal Society of Chemistry, 1997</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>Homogenous and biphasic glass</p> <p>homogenousislesseparation(SiO2richmatrix)</p> <p>interconnectedseparation</p> <p>islesseparation(SiO2-Na2Omatrix)</p> <p>SiO2 Na2O</p> <p>Introduction to glass science and technology, J. E. Shelby, The Royal Society of Chemistry, 1997</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>Examples:</p> <p>sodium-borosilicate glass</p> <p>Introduction to glass science and technology, J. E. Shelby, The Royal Society of Chemistry, 1997</p> <p>barium-silicate glass</p> <p>sodium-silicate glass</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>lithium-sodium-silicate glass alkali-borosilicate glass</p> <p>microporousand/orVycorglass</p> <p>TC=111Cwith2mol%Al2O3</p> <p>Introduction to glass science and technology, J. E. Shelby, The Royal Society of Chemistry, 1997</p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>V.M. Sglavo GlassEng - UNITN 2017 </p> <p>Technological implications</p> <p>- trasparence - opacity (d visible wavelength = 450-700 nm)</p> <p>- heterogeneous nucleation crystallization</p> <p>- production of high silica glass (Vycor)</p> <p>sodium-borosilicateglass</p> <p>thermaltreatment chemicaletchinginhotacidsolution(HCl)</p> <p>sinteringspinodaldecomposition:96%SiO2+sodium-borosilicateglass</p> <p>96%SiO2porousglass(d=2-200nm)</p> <p>96%SiO2glass</p>