Resumo

SANTOS, Rodrigo; BASTOS, João; SANTOS, Luís F.  e  ALMEIDA, Rui M.. Vidros Cerâmicos Nanocristalinos Transparentes. C.Tecn. Mat. [online]. 2009, vol.21, n.1-2, pp.11-26. ISSN 0870-8312.

Glass ceramics containing nanocrystalline phases that present non-linear optical properties, namely second harmonic generation (SHG), have potential application in photonics, namely in all-optical and electro-optical systems. The goal of this work was the preparation and characterization of glass samples in the system GeO₂∙SiO₂∙Nb₂O₅∙K₂O, as well as the production of transparent, nanocrystalline glass ceramics. The glass samples were prepared and characterized by density, DTA and Raman spectroscopy measurements. An increase in density and a decrease in T_g and T_x-T_g were observed with increasing amount of GeO₂. Heat treatments were performed and the crystalline phases K_3.8Nb₅Ge₃O_20.4 and K₃Nb₃Si₂O₁₃ were identified and related with the first exothermic peak of the DTA analysis. A germanosilicate composition with 50 mol% of glass former showed good ability to undergo bulk crystallization. In fact, a transparent glass ceramic containing crystal sizes of ~20-25 nm, was obtained.

Palavras-chave : Transparent Glass Ceramics; Niobium Germanosilicate glasses; Bulk Crystallization.

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