Seminário
Local: Departamento de Física – UFC
Data: 27/09/2013 (sexta-feira)
Horário: 16 h
Integral Strain in Small Crystalline Particles and Its Influence on Their Growth and Quality
R.I. Ristic, Department of Chemical & Biological Department, University of Sheffield
The influence of integral strain on the growth rate of crystalline materials will be presented. On the basis of the results, it is proposed that growth rate dispersion of secondary nuclei arises as a result of competition between stress reduction and dislocation enhancement of growth rates in the developing particles, with the former being the major influence at low particle sizes. The results are shown to account for the particle size and material dependence of the dispersion. Mechanistic studies suggest that the principal mechanism of stress reduction in growth rate is the influence of the applied stress induced by mechanical or electromagnetic energy on the surface free energy of the crystal. This affects both nucleation at the growth centre and the migration of growth steps across the crystal surface. A possible optimization of the strain content in microcrystals grown in batch crystallizer will be considered. Finally, the role of dislocations in habit modification of small particles will be briefly considered against widely accepted stereochemical recognition paradigm.
Vídeo do Seminário (parte 1)
Vídeo do Seminário (parte 2)
