Download presentation

Presentation is loading. Please wait.

Published byJaylan Woolson Modified over 2 years ago

1
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

2
VILA & FU AVČR & UPCE KLASICKÁ NUKLEAČNE RASTOVÁ TEÓRIA A JEJ APLIKÁCIE Marek Liška, Mária Chromčíková, Miroslava Rodová, Karel Nitsch, Zdeněk Černošek

3
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

4
PERSISTING WARNING NOT TOO MUCH THEORY !!!!!!!!!!!!

5
GIBBS ENERGY T liq Undercooling

6
VOLUME VERSUS SURFACE Critical nucleus – critical radius r * :

7
VOLUME VERSUS SURFACE

8
Thermodynamic activation barrier: MISSION IMPOSSIBLE Entropy of mixing decreases G:

9
Proportional to # of neighbors, N s, frequency, kT/h, Boltzman factor of kinetic activation energy, and N r* : HOMOGENEOUS NUCLEATION RATE

10
Decreases with T Increases with T = 0 for T=T fp

11
RATE OF CRYSTAL GROWTH

12
NUCLEATION vs CRYSTAL GROWTH T T fp fp G m 0 u 0 T 0 u 0 T fp TgTg

13
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

14
TTT DIAGRAMS TTT diagram of salol (A) = (B) = 10 -8

15
THE MODEL

16
REGRESSION TREATMENT

17
RESULTS A = B = C = G a = 97 kJ/mol s apr = 3.4 K

18
RESULTS

19
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.

20
GENERAL CONCLUSIONS Some people do not like theory...

21
AT LEAST ONE EXPERIMENT PLEASE!!! (Prayer of Mia Farrow) Photo © Z. Černošek

22
THANK YOU FOR YOUR PATIENT ATTENTION

Similar presentations

© 2016 SlidePlayer.com Inc.

All rights reserved.

Ads by Google