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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Cassar, Daniel R. ; Lancelotti, Ricardo F. ; Nuernberg, Rafael ; Nascimento, Marcio L. F. ; Rodrigues, Alisson M. ; Diz, Luiza T. ; Zanotto, Edgar D.
Total Authors: 7
Document type: Journal article
Source: Journal of Chemical Physics; v. 147, n. 1 JUL 7 2017.
Web of Science Citations: 9

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)

FAPESP's process: 15/20681-8 - Crystal growth and structural relaxation in lead metasilicate glass
Grantee:Ricardo Felipe Lancelotti
Support Opportunities: Scholarships in Brazil - Scientific Initiation
FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
Grantee:Edgar Dutra Zanotto
Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC