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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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