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Kinetics of physical aging of a silicate glass following temperature up- and down-jumps

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Autor(es):
Lancelotti, Ricardo F. ; Zanotto, Edgar D. ; Sen, Sabyasachi
Número total de Autores: 3
Tipo de documento: Artigo Científico
Fonte: Journal of Chemical Physics; v. 160, n. 3, p. 10-pg., 2024-01-21.
Resumo

In this article, we investigate the structural relaxation of lithium silicate glass during isothermal physical aging by monitoring the temporal evolution of its refractive index and enthalpy following relatively large (10-40 degrees C) up- and down-jumps in temperature. The Kohlrausch-Williams-Watts function aptly describes the up- and down-jump data when analyzed separately. For temperature down-jumps, the glass exhibits a typical stretched exponential kinetic behavior with the non-exponentiality parameter beta < 1, whereas up-jumps show a compressed exponential behavior (beta > 1). We analyzed these datasets using the non-exponential and non-linear Tool-Narayanaswamy-Moynihan (TNM) model, aiming to provide a comprehensive description of the primary or alpha-relaxation of the glass. This model described both up- and down-jump datasets using a single value of beta <= 1. However, the standard TNM model exhibited a progressively reduced capacity to describe the data for larger temperature jumps, which is likely a manifestation of the temperature dependence of the non-exponentiality or non-linearity of the relaxation process. We hypothesize that the compressed exponential relaxation kinetics observed for temperature up-jumps stems from a nucleation-growth-percolation-based evolution on the dynamically mobile regions within the structure, leading to a self-acceleration of the dynamics. On the other hand, temperature down-jumps result in self-retardation, as the slow-relaxing denser regions percolate in the structure to give rise to a stretched exponential behavior. (AU)

Processo FAPESP: 22/07679-8 - Origem em escala atômica da relaxação estrutural de vidros metassilicato de chumbo e dissilicato de lítio
Beneficiário:Ricardo Felipe Lancelotti
Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
Processo FAPESP: 21/03374-5 - Relaxação estrutural de vidros e sua influência em outros processos dinâmicos
Beneficiário:Ricardo Felipe Lancelotti
Modalidade de apoio: Bolsas no Brasil - Doutorado
Processo FAPESP: 13/07793-6 - CEPIV - Centro de Ensino, Pesquisa e Inovação em Vidros
Beneficiário:Edgar Dutra Zanotto
Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs