| Texto completo | |
| Autor(es): |
Reinsch, Stefan
[1]
;
Nascimento, Marcio Luis Ferreira
[2]
;
Mueller, Ralf
[1]
;
Zanotto, Edgar Dutra
[2]
Número total de Autores: 4
|
| Afiliação do(s) autor(es): | [1] Fed Inst Mat Res & Testing, D-12205 Berlin - Germany
[2] Univ Fed Sao Carlos, Vitreous Mat Lab, Dept Mat Engn, BR-13595905 Sao Carlos, SP - Brazil
Número total de Afiliações: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Non-Crystalline Solids; v. 354, n. 52-54, p. 5386-5394, DEC 15 2008. |
| Citações Web of Science: | 35 |
| Resumo | |
We measured and collected literature data for the crystal growth rate, u(T), of mu-cordierite (2MgO center dot 2Al(2)O(3) center dot 5SiO(2)) and diopside (CaO center dot MgO center dot 2SiO(2)) in their isochemical glass forming melts. The data cover exceptionally wide temperature ranges, i.e. 800-1350 degrees C for cordierite and 750-1378 degrees C for diopside. The maximum of u(T) occurs at about 1250 degrees C for both systems. A smooth shoulder is observed around 970 degrees C for mu-cordierite. Based on measured and collected viscosity data, we fitted u(T) using standard crystal growth models. For diopside, the experimental u(T) fits well to the 2D surface nucleation model and also to the screw dislocation growth mechanism. However, the screw dislocation model yields parameters of more significant physical meaning. For cordierite, these two models also describe the experimental growth rates. However, the best fittings of u(T) including the observed shoulder, were attained for a combined mechanism, assuming that the melt/crystal interface growing from screw dislocations is additionally roughened by superimposed 2D surface nucleation at large undercoolings. starting at a temperature around the shoulder. The good fittings indicate that viscosity can be used to assess the transport mechanism that determines crystal growth in these two systems, from the melting point T(m) down to about T(g). with no sign of a breakdown of the Stokes-Einstein/Eyring equation. (C) 2008 Elsevier B.V. All rights reserved. (AU) | |
| Processo FAPESP: | 04/10703-0 - Crescimento de cristais em vidros óxidos: testes de modelos e do possível desacoplamento entre difusão iônica e fluxo viscoso |
| Beneficiário: | Marcio Luis Ferreira Nascimento |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 07/08179-9 - Processos cinéticos em vidros e vitrocerâmicas |
| Beneficiário: | Edgar Dutra Zanotto |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |