Autor(es)

Revelo, Raul Julian ; Souza, Mauricio Lima ; Pena, Rafaella Bartz ; Yoshida, Satoshi ; Zanotto, Edgar Dutra

• Tipo de documento: Artigo Científico
• Fonte: CERAMICS INTERNATIONAL; v. 51, n. 20, p. 13-pg., 2025-08-25.

Resumo

ZrO2 is one of the most effective and widely used nucleating agents in various families of glass-ceramics; however, its detailed mechanism remains a subject of debate. Understanding its nucleation mechanism requires a thorough analysis of microstructural evolution and the identification of factors influencing this process. This study investigates the effects of ZrO2 incorporation on the internal nucleation and microstructural evolution in stoichiometric LAS (Li2O center dot Al2O3 center dot nSiO2) glass-ceramics of varying composition. Glasses with different SiO2 molar ratios (n = 2, 4, 5, and 6) were prepared with ZrO2 additions of 3.0 and 3.5 mol%. Several thermal treatments were employed, followed by characterization using XRD, SEM, STEM, and Raman spectroscopy. The results indicate that a minimum of 3.5 mol% ZrO2 is required to induce internal nucleation in LAS glasses with n = 4, 5, and 6. In these compositions, Zr-enriched regions formed through liquid-liquid phase separation serve as preferential sites for ZrO2 crystal precipitation, which subsequently induces the nucleation of beta-quartz solid solution. Upon further treatment at higher temperatures, this metastable phase transforms into beta-spodumene or its solid solution. As expected, increasing SiO2 content enhances glass network polymerization, as evidenced by the increased presence of Q3 species in Raman spectroscopy, leading to higher characteristic temperatures of glass transition and peak crystallization in DSC analyses. A higher SiO2 content results in fewer but larger crystals, whereas a lower SiO2 content promotes a higher number density of crystals within the glass matrix. (AU)

• Processo FAPESP: 13/07793-6 - CeRTEV - Centro de Pesquisa, Tecnologia e Educação em Materiais Vítreos
• Beneficiário: Edgar Dutra Zanotto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 23/17069-5 - Papel Estrutural dos Óxidos de Metais de Transição em Vidros de Borato e Fosfato Estudado por Técnicas de Ressonância Magnética Dipolar de Núcleos Quadrupolares
• Beneficiário: Rafaella Bartz Pena
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado