Autor(es)

Bradtmuller, Henrik ; Zheng, Qiuju ; Eckert, Hellmut ; Zanotto, Edgar D.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Non-Crystalline Solids; v. 641, p. 11-pg., 2024-07-26.

Resumo

This study presents a detailed structural analysis of the glass-to-crystal transition in the technologically important LiNbO3-SiO2 3 - SiO 2 glass system, focusing on the composition 35Li2O-25Nb2O5-40SiO2 2 O-25Nb 2 O 5 - 40SiO 2 known for its exceptional second harmonic generation (SHG) response in glass-ceramics. We develop a comprehensive solid-state NMR protocol to quantify major and minor fractions of elusive nanocrystalline phases and the residual glass composition, overcoming limitations of techniques such as X-ray diffraction and Raman spectroscopy. By employing 7 Li satellite transition difference spectroscopy and 93 Nb magic-angle spinning (MAS) NMR, we achieve quantification of crystalline fractions down to 1%. By combining all the complementary 6 Li, 7 Li, 29 Si, and 93 Nb MAS NMR experiments, we also deduce the composition of the residual glass. Short crystallization times (up to 120 min) at 640 degrees C result in nanocrystalline LiNbO3, 3 , whereas crystallization for 1440 min at this temperature additionally yields two Li2Si2O5 2 Si 2 O 5 polymorphs and Li2SiO3. 2 SiO 3 . 7 Li spin echo and 7 Li{ 93 Nb} W-RESPDOR NMR spectroscopy indicate that LiNbO3 3 crystallizes in specific domains leaving behind SiO2-rich 2-rich residual glassy domains. This work offers a time-efficient and versatile NMR protocol for characterizing crystalline and residual glass components in nanocrystalline glass-ceramics in the LiNbO3-SiO2 3 - SiO 2 system and beyond, providing valuable insights into the crystallization process which is not possible with other techniques. (AU)

• Processo FAPESP: 19/26399-3 - Elucidação de rearranjos estruturais durante o processo de relaxação e cristalização de materiais vítreos
• Beneficiário: Henrik Bradtmüller
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• 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