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 , Slovak Republic

VILA & FU AVČR & UPCE KLASICKÁ NUKLEAČNE RASTOVÁ TEÓRIA A JEJ APLIKÁCIE Marek Liška, Mária Chromčíková, Miroslava Rodová, Karel Nitsch, Zdeněk Černošek

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

PERSISTING WARNING NOT TOO MUCH THEORY !!!!!!!!!!!!

GIBBS ENERGY T liq Undercooling

VOLUME VERSUS SURFACE Critical nucleus – critical radius r * :

VOLUME VERSUS SURFACE

Thermodynamic activation barrier: MISSION IMPOSSIBLE Entropy of mixing decreases  G:

Proportional to # of neighbors, N s, frequency, kT/h, Boltzman factor of kinetic activation energy, and N r* : HOMOGENEOUS NUCLEATION RATE

Decreases with T  Increases with T  = 0 for T=T fp

RATE OF CRYSTAL GROWTH

NUCLEATION vs CRYSTAL GROWTH T  T fp   fp G m  0  u  0 T  0  u  0 T fp TgTg

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

TTT DIAGRAMS TTT diagram of salol (A)  = (B)  = 10 -8

THE MODEL

REGRESSION TREATMENT

RESULTS A = B = C =  G a = 97 kJ/mol s apr = 3.4 K

RESULTS

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.

GENERAL CONCLUSIONS Some people do not like theory...

AT LEAST ONE EXPERIMENT PLEASE!!! (Prayer of Mia Farrow) Photo © Z. Černošek

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