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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Elemental and cooperative diffusion in a liquid, supercooled liquid and glass resolved

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Autor(es):
Cassar, Daniel R. ; Lancelotti, Ricardo F. ; Nuernberg, Rafael ; Nascimento, Marcio L. F. ; Rodrigues, Alisson M. ; Diz, Luiza T. ; Zanotto, Edgar D.
Número total de Autores: 7
Tipo de documento: Artigo Científico
Fonte: Journal of Chemical Physics; v. 147, n. 1 JUL 7 2017.
Citações Web of Science: 9
Resumo

The diffusion mechanisms controlling viscous flow, structural relaxation, liquid-liquid phase separation, crystal nucleation, and crystal growth in multicomponent glass-forming liquids are of great interest and relevance in physics, chemistry, materials, and glass science. However, the diffusing entities that control each of these important dynamic processes are still unknown. The main objective of this work is to shed some light on this mystery, advancing the knowledge on this phenomenon. For that matter, we measured the crystal growth rates, the viscosity, and lead diffusivities in PbSiO3 liquid and glass in a wide temperature range. We compared our measured values with published data covering 16 orders of magnitude. We suggest that above a certain temperature range Td (1.2Tg-1.3Tg), crystal growth and viscous flow are controlled by the diffusion of silicon and lead. Below this temperature, crystal growth and viscous flow are more sluggish than the diffusion of silicon and lead. Therefore, Td marks the temperature where decoupling between the (measured) cationic diffusivity and the effective diffusivities calculated from viscosity and crystal growth rates occurs. We reasonably propose that the nature or size of the diffusional entities controlling viscous flow and crystal growth below Td is quite different; the slowest is the one controlling viscous flow, but both processes require cooperative movements of some larger structural units rather than jumps of only one or a few isolated atoms. Published by AIP Publishing. (AU)

Processo FAPESP: 15/20681-8 - Crescimento de cristais e relaxação estrutural em metassilicato de chumbo vítreo
Beneficiário:Ricardo Felipe Lancelotti
Linha de fomento: Bolsas no Brasil - Iniciação Científica
Processo FAPESP: 13/07793-6 - CEPIV - Centro de Ensino, Pesquisa e Inovação em Vidros
Beneficiário:Edgar Dutra Zanotto
Linha de fomento: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs