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VILA VÍLA - VItrum LAugaricio Joint Glass Center of Institute of Inorganic Chemistry of SAS, A. Dubček University of Trenčín, and RONA, j.s.c. Študentská 2, Trenčín, SK-911 50, Slovak Republic
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VILA & FU AVČR & UPCE KLASICKÁ NUKLEAČNE RASTOVÁ TEÓRIA A JEJ APLIKÁCIE Marek Liška, Mária Chromčíková, Miroslava Rodová, Karel Nitsch, Zdeněk Černošek
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OUTLINE Gibbs energy controls the [P, T] world Driving force for crystallization Crystal nucleation - embryo Crystal growth Nucleation and growth – TTT Mathematical model Application to ZnCl 2
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PERSISTING WARNING NOT TOO MUCH THEORY !!!!!!!!!!!!
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GIBBS ENERGY T liq Undercooling
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VOLUME VERSUS SURFACE Critical nucleus – critical radius r * :
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VOLUME VERSUS SURFACE
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Thermodynamic activation barrier: MISSION IMPOSSIBLE Entropy of mixing decreases G:
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Proportional to # of neighbors, N s, frequency, kT/h, Boltzman factor of kinetic activation energy, and N r* : HOMOGENEOUS NUCLEATION RATE
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Decreases with T Increases with T = 0 for T=T fp
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RATE OF CRYSTAL GROWTH
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NUCLEATION vs CRYSTAL GROWTH T T fp fp G m 0 u 0 T 0 u 0 T fp TgTg
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NUCLEATION AND GROWTH Constant p, T, single component => u, I = const. Volume after growth from to t V cr V liq = const TTT = Temperature – Time – Transformation
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TTT DIAGRAMS TTT diagram of salol (A) = 10 -6 (B) = 10 -8
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THE MODEL
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REGRESSION TREATMENT
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RESULTS A = - 49.11 B = 46916278 C = 46795 G a = 97 kJ/mol s apr = 3.4 K
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RESULTS
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CONCLUSION The plausible semi-empirical method (e.g. the general form of the regression function) was proposed for the quantitative description of the TTT diagrams.
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GENERAL CONCLUSIONS Some people do not like theory...
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AT LEAST ONE EXPERIMENT PLEASE!!! (Prayer of Mia Farrow) Photo © Z. Černošek
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THANK YOU FOR YOUR PATIENT ATTENTION
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